摘要
Plant-based diets (PBDs) are associated with environmental benefits, human health promotion and animal welfare. There is a worldwide shift towards PBDs, evident from the increased global demand for fresh plant-based products (PBPs). Such shifts in dietary preferences accompanied by evolving food palates, create opportunities to leverage technological advancements and strict quality controls in developing PBPs that can drive consumer acceptance. Flavor, color and texture are important sensory attributes of a food product and, have the largest influence on consumer appeal and acceptance. Among these, flavor is considered the most dominating quality attribute that significantly affects overall eating experience. Current state-of-art technologies rely on physicochemical estimations and sensory-based tests to assess flavor-related attributes in fresh PBPs. However, these methodologies often do not provide any indication about the metabolic features associated with unique flavor profiles and, consequently, can be used in a limited way to define the quality attributes of PBPs. To this end, a systematic understanding of metabolites that contribute to the flavor profiles of PBPs is warranted to complement the existing methodologies. This review will discuss the use of metabolomics for evaluating flavor-associated metabolites in fresh PBPs at post-harvest stage, alongside its applications for quality assessment and grading. We will summarize the current research in this area, discuss technical challenges and considerations pertaining to sampling and analytical techniques, as well as s provide future perspectives and directions for government organizations, industries and other stakeholders associated with the quality assessment of fresh PBPs.
植物性饮食(PBDs)与环境效益、促进人类健康和动物福利有关。从全球对新鲜植物性产品(PBPs)需求的增加可以看出，全球正在向PBDs转变。这种饮食偏好的转变伴随着不断变化的食物口味，为利用技术进步和严格的质量控制来开发能够推动消费者接受的pbp创造了机会。风味、颜色和质地是食品重要的感官属性，对消费者的吸引力和接受程度影响最大。其中，风味被认为是影响整体饮食体验的最主要品质属性。目前最先进的技术依赖于物理化学估计和基于感官的测试来评估新鲜PBPs中的风味相关属性。然而，这些方法通常不能提供与独特风味特征相关的代谢特征的任何指示，因此，只能以有限的方式用于定义PBPs的质量属性。为此，有必要对影响PBPs风味特征的代谢物进行系统的了解，以补充现有的方法。这篇综述将讨论在收获后阶段，利用代谢组学评估新鲜PBPs中与风味相关的代谢物的方法，以及该方法在质量评估和分级中的应用。我们将总结这一领域的当前研究，讨论与采样和分析技术相关的技术挑战和注意事项，并为与政府组织、工业界以及其他与新鲜PBPs质量评估相关的利益相关者提供未来展望和发展方向。
Keywords: 关键词：
plant-based diets; plant-based products; metabolomics; sensory attributes; flavor
植物性饮食；植物性产品；代谢组学；感官属性；风味
1.1. 全球食品口味：迈向可持续的未来食品
Increasing urbanization, rising per capita incomes and affordability are shaping the way our food is produced and consumed globally. The associated changes in lifestyle are influencing the composition of food baskets, food consumption patterns and behaviors [1,2,3,4]. With the advent of digitalization and increased access to information, consumers are becoming more cognizant about food and its sources [5]. There is increasing focus on well-being and shifts in consumer preferences toward foods that are grown sustainably. Consequently, plant-based diets (PBDs) are gaining popularity owing to their numerous environmental and human health benefits [6].
日益加剧的城市化、人均收入的增加以及消费能力的提升正在全球范围内重塑食品的生产和消费方式。伴随而来的生活方式变化正影响着食品篮子的构成、食品消费模式和行为习惯[1,2,3,4]。随着数字化时代的到来和信息获取的便捷性提高，消费者对食品及其来源的认知度也在不断增强[5]。人们越来越关注健康福祉，消费偏好也逐渐转向可持续种植的食品。因此，植物性饮食（PBDs）因其众多的环境和人类健康益处而日益受到欢迎[6]。
1.2. 植物性饮食：我们了解什么？
Diet refers to a lifestyle adopted by an individual, and largely relates to an eating plan and regimen for habitual nourishment. With PBD, an individual relies on plant-based products (PBPs) for his/her daily nutritional needs. Typical PBDs maximize the consumption of nutrient-rich plant foods while minimizing processed foods, oils, and animal foods (including dairy products and eggs) [7]. It is pertinent to note that at present, there are varying opinions in the scientific community about idealistic PBDs. However, there is a general cognizance that PBDs are associated with a multitude of human and environmental health benefits. Some epidemiological and interventional human studies have suggested that PBDs exert beneficial health effects against obesity-related metabolic dysfunction, type 2 diabetes mellitus and chronic low-grade inflammation [8,9,10]. Furthermore, the production of PBDs tend to be less resource-intensive and more environmentally friendly for various reasons, including lowered levels of greenhouse gas emissions (GHGEs), in comparison to raising animals for human consumption [11].
饮食是指个人所采取的生活方式，主要与日常饮食计划和习惯营养有关。在植物性饮食（PBD）中，个体依赖植物性产品（PBPs）来满足其日常营养需求。典型的植物性饮食会最大化营养丰富的植物性食物的摄入量，同时尽量减少加工食品、油脂和动物性食物（包括乳制品和鸡蛋）的摄入量[7]。值得注意的是，目前科学界对于理想化的植物性饮食存在不同意见。然而，普遍认识到的是，植物性饮食与人类和环境的健康益处息息相关。一些流行病学和干预性人体研究表明，植物性饮食对与肥胖相关的代谢功能障碍、2型糖尿病和慢性低度炎症具有有益的健康影响[8,9,10]。此外，与饲养动物供人类食用相比，植物性饮食的生产往往资源消耗较少且更加环保，包括温室气体排放量较低[11]。
As most PBDs rely heavily on plant-based products (PBPs), there will be an increased global demand for PBPs to meet the changing consumer preferences. For the purpose of this review, the scope will be limited to fresh PBPs at the post-harvest stage, where the produce makes its first entry for quality assessments.
由于大多数植物性饮食严重依赖植物性产品（PBPs），因此为了满足不断变化的消费者偏好，全球对PBPs的需求将会增加。为了本综述的目的，其范围将仅限于收获后阶段的新鲜PBPs，即这些产品在首次进行质量评估时所处的阶段。
1.3. 植物性产品：营养和感官特性
PBPs comprise of vegetables, fruits, lentils, grains, legumes, nuts and seeds. They offer a myriad of nutritional and functional benefits for human health promotion. Apart from macronutrients and micronutrients, many of these PBPs provide a range of bioactive compounds to combat inflammation, strengthen antioxidant defenses, and general immune system [12,13,14].
植物性产品（PBPs）包括蔬菜、水果、扁豆、谷物、豆类、坚果和种子。它们为人类健康促进提供了众多的营养和功能益处。除了宏量营养素和微量营养素外，许多PBPs还提供了一系列生物活性化合物，以对抗炎症、增强抗氧化防御和整体免疫系统[12,13,14]。
A considerable fraction of bioactive compounds/metabolites in PBPs, such as pigments, phytochemicals and other secondary metabolites, contribute to the sensory properties of fresh PBPs. Flavor, color and texture together contribute to the overall eating experience associated with PBPs, and are often a deterministic factor in influencing consumer acceptance. Among these three sensory properties, flavor often has the highest influence on consumer acceptance and behavior. Apart from being a critical quality attribute, flavor also provides valuable information about the nutritional quality of the food [15]. While consumers generally recognize flavor as the most dominant quality attribute for certain PBPs such as fruits and vegetables, it is the interaction of flavor and texture that has a significant effect on consumer acceptance of PBPs [16]. However, for the purpose of this review, we will focus on flavor-related attributes of fresh PBPs.
在植物性产品（PBPs）中，相当大一部分的生物活性化合物/代谢物，如色素、植物化学物质和其他次级代谢物，对新鲜PBPs的感官特性有所贡献。风味、颜色和质地共同构成了与PBPs相关的整体食用体验，并且通常是影响消费者接受度的决定性因素。在这三种感官特性中，风味往往对消费者的接受度和行为有最大的影响。除了是关键的质量属性外，风味还提供了关于食物营养质量的有价值信息[15]。虽然消费者通常认为风味是某些PBPs（如水果和蔬菜）最显著的质量属性，但风味和质地的相互作用对消费者接受PBPs有显著影响[16]。然而，为了本综述的目的，我们将重点关注新鲜PBPs与风味相关的属性。
Flavor is perceived primarily by the sense of taste and olfaction (aromatics/aroma) [17]. Aroma and taste receptors, located in the nose and mouth, respectively, are responsible for distinct flavor recognition. It is generally accepted that olfactory stimuli (aroma metabolites) contribute significantly to the flavor experience of most food products. The unique taste sensations and aroma associated with PBPs come from a complex mixture of compounds that belong to different chemical classes. They originate from the primary and secondary metabolism in PBPs and are generally bioactive, with aroma metabolites being volatile in nature while, the taste metabolites often being non-volatile. Both the volatile and non-volatile bioactive fraction in PBPs, such as phenols, flavonoids, isoflavones, terpenes, and glucosinolates, contribute to bitter, acidic, or astringent flavor profiles [18,19]. The presence of these bioactive compounds is an intrinsic property of PBPs, and their synthesis is often influenced by multiple genetic and environmental factors [20,21,22]. Considering the diverse nature of these bioactive compounds and their contribution to the flavor of fresh PBPs, an inclusive approach for their quality assessment at the post-harvest stage is valuable for entire supply chain management. The significance of including a detailed characterization of bioactive compounds for quality assessment has received considerable attention for certain processed food products [23,24,25]. However, quality assessment for fresh PBPs at the post-harvest stage mainly relies on conventional techniques, as discussed in the next section.
风味主要通过味觉和嗅觉（即香气）来感知[17]。分别位于鼻子和口中的香气和味觉受体负责不同的风味识别。通常认为，嗅觉刺激（香气代谢产物）对大多数食品的风味体验有着显著的贡献。与PBPs相关的独特味觉感受和香气来自于属于不同化学类别的复杂化合物混合物。这些化合物来源于PBPs的初级和次级代谢，并且通常具有生物活性，其中香气代谢产物具有挥发性，而味觉代谢产物则通常不具有挥发性。PBPs中的挥发性和非挥发性生物活性成分，如酚类、黄酮类、异黄酮类、萜烯类和硫代葡萄糖苷等，都会给风味带来苦、酸或涩的特征[18,19]。这些生物活性化合物的存在是PBPs的内在特性，并且它们的合成往往受到多种遗传和环境因素的影响[20,21,22]。考虑到这些生物活性化合物的多样性和它们对新鲜PBPs风味的贡献，在收获后对它们进行质量评估的全面方法对于整个供应链的管理具有重要意义。对于某些加工食品产品，在质量评估中包括生物活性化合物的详细表征已受到相当大的关注[23,24,25]。然而，对于新鲜PBPs在收获后的质量评估，主要还是依赖于传统技术，这将在接下来的部分中讨论。
PBPs的质量评估
2.1. 收获后处理：与风味相关属性的当前先进技术
At present, the post-harvest quality assessment of fresh PBPs is effectively regulated for attributes related to food safety/human health risk (heavy metals, chemical contamination, microbiological), but loosely regulated for attributes associated with consumer acceptance and eating experience. These regulations are imposed both at international and national levels, as well as within the individual supply chains [26]. Current quality assessment parameters do not effectively inform on the kind of metabolites or chemical compounds that are responsible for the unique flavor profiles of fresh PBPs. However, this could be particularly important for formulating new products in this domain, keeping in mind the changing consumption trends and evolving flavor preferences.
目前，新鲜PBPs的收获后质量评估在食品安全/人类健康风险（重金属、化学污染、微生物）相关的属性上得到了有效的监管，但在与消费者接受度和食用体验相关的属性上监管较为宽松。这些监管措施在国际、国家层面以及各个供应链内部都得到了实施[26]。然而，当前的质量评估参数并未有效地提供关于哪种代谢物或化学化合物负责新鲜PBPs独特风味特征的信息。但是，这对于该领域新产品的配方制定可能尤为重要，特别是考虑到不断变化的消费趋势和不断演变的风味偏好。
For any PBP, the relative importance of a quality attribute depends on the commodity and its end-use [27]. In general, the post-harvest handling steps for PBPs include identification of the key quality attributes from food safety/human health-related risks (minimum statutory requirements), followed by establishing quality control/quality assurance (QA/QC) procedures to (i) maintain acceptable quality level for the consumer; and (ii) ensure that minimum quality standards are met.
对于任何PBP，一个质量属性的相对重要性取决于该商品及其最终用途[27]。一般来说，PBPs的收获后处理步骤包括首先识别与食品安全/人类健康风险相关的关键质量属性（法定最低要求），然后建立质量控制/质量保证（QA/QC）程序，以（i）保持消费者可接受的质量水平；（ii）确保达到最低质量标准。
The quality assessment of fresh PBPs routinely involves sensory and instrumental methods. In general, sensory methods are used for developing new products and determining product standards, while instrumental methods fare better in assessing the quality of the fresh PBPs on a routine basis [28]. Sensory evaluation is usually performed by a trained sensory panel, and it has two components: the analytical component, which is used to detect differences in products, and affective measurements, which determine preference. Instrumental measurements, on the other hand, focus on the chemical and physical characteristics of PBPs, and encompass a wide range of techniques to determine flavor attributes. For example, a hydrometer that can detect total soluble solids is often used to determine sugar levels while, pH meter is used to measure the level of sourness in food products [28].
新鲜PBPs（植物性产品）的质量评估通常涉及感官方法和仪器方法。一般来说，感官方法用于开发新产品和确定产品标准，而仪器方法在日常评估新鲜PBPs的质量方面表现更佳[28]。感官评价通常由经过培训的感官评估小组进行，包括两个组成部分：分析性成分，用于检测产品之间的差异；以及情感测量，用于确定偏好。另一方面，仪器测量则侧重于PBPs的化学和物理特性，并采用多种技术来确定风味属性。例如，检测总可溶性固体的比重计常用于确定糖分水平，而pH计则用于测量食品产品的酸度水平[28]。
2.2. Gaps in Current Technologies and Need for Complementary Approaches
2.2 当前技术的不足与互补方法的需求
Instrumental techniques aimed at evaluating the physical and chemical characteristics of PBPs are advantageous as they: (i) provide high accuracy and great precision; (ii) are often more sensitive to small differences between samples, which assist in determining quality trends; and (iii) they are high-throughput and are often available in semi-automated and automated formats [29]. However, the physicochemical characteristics of PBPs have little relevance to consumer acceptability and thus, the results can be used in a limited way to define the quality attributes of PBPs [30]. For this purpose, sensory evaluation is often recommended to accurately assess the quality attributes of fresh PBPs. Sensory evaluation also has certain disadvantages as it requires a trained sensory panel and it is often time consuming, laborious and challenging.
旨在评估PBPs物理和化学特性的仪器技术具有优势，因为它们：（i）提供高精度和高准确性；（ii）通常对样品之间的小差异更敏感，有助于确定质量趋势；（iii）具有高通量，并且通常以半自动和自动格式提供[29]。然而，PBPs的物理化学特性与消费者接受度之间的相关性很小，因此这些结果只能以有限的方式用于定义PBPs的质量属性[30]。为此，通常建议采用感官评价来准确评估新鲜PBPs的质量属性。然而，感官评价也存在一些缺点，如需要训练有素的感官评估小组，且往往耗时、费力且具有挑战性。
To complement and extend the repertoire of the existing methodologies, detailed and quantitative analyses to measure flavor-associated metabolites are warranted. Integrating such technologies in current quality assessment of fresh PBPs will (i) ensure product uniformity; (ii) strengthen consumer acceptability for PBDs and PBPs in general; (iii) complement current assessment platforms for quality and food safety of fresh PBPs; and (iv) aid in determining maturity and degree of ripening of PBPs at the post-harvest stage.
为了补充和扩展现有方法体系，对与风味相关的代谢产物进行详细和定量的分析是必要的。将此类技术整合到新鲜PBPs（植物性产品）的当前质量评估中，将（i）确保产品的一致性；（ii）增强消费者对PBDs（可能是指植物基产品或其他相关术语，但在此上下文中可能指的是广义上的植物性产品）和PBPs的总体接受度；（iii）补充当前对新鲜PBPs质量和食品安全的评估平台；（iv）有助于确定收获后PBPs的成熟度和成熟程度。
3. Metabolite Fingerprinting for Quality Assessment of PBPs
3. PBPs质量评估的代谢物指纹图谱
3.1 农食领域的代谢组学：当前实践
Metabolomics allows for studying multiple small molecules or metabolites in a cell, tissue or organism. It is defined as the comprehensive characterization of small molecules present in a biological sample [31,32,33]. Metabolomics routinely utilizes sophisticated and high-throughput analytical platforms such as gas chromatography and liquid chromatography–mass spectrometry (GC–MS and LC–MS) and nuclear magnetic resonance (NMR) spectroscopy [34]. With the advent of chemometrics and advanced analytical platforms, metabolomics has greatly facilitated our understanding of the global metabolome and pathway networks [35]. Metabolomics approaches involve untargeted or targeted analyses, and the selection of the approach is largely dependent on the experimental question and expected outcomes [36]. Untargeted analyses utilize an unbiased profiling or metabolic fingerprinting approach focused on uncovering the global metabolome to evaluate diverse chemical classes of metabolites associated with different pathways. On the other hand, targeted analyses rely on a priori knowledge of the class of metabolites or pathways that are of interest [37]. However, the combination of these analyses is often required to obtain complete information of interest.
代谢组学允许研究细胞、组织或生物体中的多种小分子或代谢产物。它被定义为对生物样品中存在的小分子进行全面表征[31,32,33]。代谢组学通常使用复杂且高通量的分析平台，如气相色谱和液相色谱-质谱联用（GC-MS和LC-MS）以及核磁共振（NMR）光谱[34]。随着化学计量学和先进分析平台的出现，代谢组学极大地促进了我们对全局代谢组和代谢途径网络的理解[35]。代谢组学方法包括非靶向或靶向分析，方法的选择很大程度上取决于实验问题和预期结果[36]。非靶向分析采用无偏见的轮廓分析或代谢指纹图谱方法，专注于揭示全局代谢组，以评估与不同途径相关的多种化学类别的代谢产物。另一方面，靶向分析依赖于对感兴趣的代谢产物类别或途径的先验知识[37]。然而，为了获得完整的感兴趣信息，通常需要将这两种分析方法结合起来。
Over the past few decades, metabolomics has been extensively applied to various fields of science owing to new developments in analytical instrumentation and data-analytics platforms [38,39,40,41]. Although still in their infancy, metabolomics-based approaches have gained significant interest in the agri-food sector for a diversity of applications including food processing, quality control, plant breeding for improved crop varieties and product development [42,43]. However, at present, metabolomics-based approaches have not been adopted by the regulatory agencies for food quality assessment, although in some cases they have been found to be efficient, with clear benefits over conventional methods. For instance, metabolomics-based approaches have proved valuable to the food industry for the aroma analysis of fresh and processed PBPs [44,45,46,47]. It is pertinent to note that most of the current research in food metabolomics is focused on evaluating various quality attributes of processed/semi-processed food products. Efforts in the area of fresh produce are mostly restricted to economically important PBPs or PBPs grown for specific end-use [45].
在过去的几十年里，由于分析仪器和数据分析平台的新发展，代谢组学已被广泛应用于科学的各个领域[38,39,40,41]。尽管仍处于起步阶段，但基于代谢组学的方法在农食行业已经引起了广泛关注，并应用于多种领域，包括食品加工、质量控制、作物品种改良和产品开发[42,43]。然而，目前监管机构尚未将基于代谢组学的方法用于食品质量评估，尽管在某些情况下，这些方法已被证明是有效的，并且相对于传统方法具有明显优势。例如，基于代谢组学的方法在新鲜和加工PBPs的香气分析方面对食品工业具有重要价值[44,45,46,47]。值得注意的是，目前食品代谢组学的大部分研究都集中在评估加工/半加工食品产品的各种质量属性上。而在新鲜农产品领域的研究大多局限于经济上重要的PBPs或特定最终用途的PBPs[45]。
3.2 基于代谢组学评估新鲜PBPs中的风味相关代谢产物
Within the agri-food sector, several diverse areas utilize metabolomics approaches for a variety of applications, as discussed in the previous Section 3.1. One such application involves evaluating the flavor-associated metabolites in fresh PBPs, which are determined by their biochemical composition. As stated in earlier Section 3.1, flavor has the largest influence on consumer behavior and consumption pattern [15], and consequently, most of the research efforts in this domain are catered towards determining the flavor-related metabolites in PBPs. Perception of flavor involves both volatile aroma metabolites as well as non-volatile taste metabolites which belong to different classes.
在农食行业中，如第3.1节所述，代谢组学方法被用于多种应用。其中一项应用就是评估新鲜PBPs中的风味相关代谢产物，这些代谢产物由其生化成分决定。正如第3.1节所述，风味对消费者行为和消费模式有最大影响[15]，因此该领域的大部分研究都致力于确定PBPs中的风味相关代谢产物。风味的感知既涉及挥发性香气代谢产物，也涉及属于不同类别的非挥发性味觉代谢产物。
3.2.1 香气相关代谢产物
In fresh PBPs, a diverse set of volatile chemical compounds contribute to their natural aroma, increasing the complexity of these aroma-associated metabolites. This complexity is further compounded as the volatile compounds interact with each other to create a unique aroma profile for PBPs, which is not merely a sum of the volatile compounds present in them. To date, more than 7000 volatile compounds have been identified in foods, however, a relatively small number (300–400), in specific abundance and ratio, determine the characteristic aroma of the product [48,49].
在新鲜植物性产品（PBPs）中，一系列复杂的挥发性化合物共同构成了其自然香气，这使得香气相关代谢产物的分析变得尤为复杂。这种复杂性还体现在挥发性化合物之间的相互作用上，它们共同创造出PBPs独特的香气特征，这种特征并非仅仅是这些挥发性化合物简单加和的结果。迄今为止，食品中已鉴定出超过7000种挥发性化合物，但其中只有相对较少的一部分（300-400种），在特定的丰度和比例下，决定了产品的特征香气[48,49]。
There are several known classes of volatile aroma metabolites that contribute to the unique flavor of fresh PBPs, such as esters, alcohols, aldehydes, ketones, lactones, terpenoids and apocarotenoids. However, derivatives of amino acids, lipids, phenolic acids and sesquiterpenes are known to be the most important aroma-associated metabolites in PBPs [50]. In certain PBPs, especially fruits and vegetables, sulphurous compounds and derivatives also contribute to their distinct aroma profiles [50].
已知有多种挥发性香气代谢产物对新鲜PBPs的独特风味有贡献，如酯类、醇类、醛类、酮类、内酯类、萜类和脱辅基类胡萝卜素等。然而，在PBPs中，氨基酸、脂质、酚酸和倍半萜烯的衍生物被认为是最重要的香气相关代谢产物[50]。在某些PBPs中，特别是水果和蔬菜，含硫化合物及其衍生物也对其独特的香气特征有重要贡献[50]。
Volatile aroma metabolites associated with fresh PBPs are generally derived from phytonutrients belonging to fatty acids, amino acids, carotenoids and terpenoid classes [15,51] through a limited number of major biochemical pathways [52]. These pathways are mainly involved in the synthesis of the backbone, while the diversity of these volatiles is achieved via additional chain modification steps and further transformations. Fatty-acid derived volatiles such as alcohols, esters, ketones, acids and lactones form important character-impact aroma compounds that are responsible for flavors of fresh fruits mainly synthesized through α-oxidation, β-oxidation and the lipoxygenase pathway [53].
与新鲜PBPs相关的挥发性香气代谢产物通常来源于脂肪酸、氨基酸、类胡萝卜素和萜类化合物等植物营养素[15,51]，这些代谢产物通过有限的几个主要生化途径产生[52]。这些途径主要涉及香气化合物骨架的合成，而挥发性化合物的多样性则通过额外的链修饰步骤和进一步的转化来实现。脂肪酸衍生的挥发性物质，如醇类、酯类、酮类、酸类和内酯类，是构成新鲜水果风味的重要特征香气化合物，它们主要通过α-氧化、β-氧化和脂氧合酶途径合成[53]。
Similarly, amino acid-derived volatile compounds are produced either through amino-acid precursors (direct) or through acyl-coAs (indirect) and they mainly belong to alcohols, esters, and vegetables. Amino acid-derived volatiles represent dominant classes in PBPs, specifically fruits, vegetables, and grains [15,19,54,55]. For instance, the amino acid proline is the nitrogen precursor for 2-acetyl-1-pyrroline, a volatile compound that is associated with the aroma of certain rice varieties. Similarly, methionine and tryptophan are involved in side-chain modifications of sulphur containing glucosinolates, which result in volatile degradation products, namely isothiocyanates, that contribute to the characteristic aroma associated with Brassica genus [56]. Terpenoids make up the largest class of plant secondary metabolites, many of them being volatile in nature, that contribute to the aroma of fresh PBPs. Hemiterpenes (C5), monoterpenes (C10), sesquiterpenes (C15), homoterpenes (C11 and C16), and some diterpenes (C20) have higher vapor pressure, allowing their release into the surrounding atmosphere and volatilize. All the terpenoids are derived from the universal C5 precursor isopentenyl diphosphate (IPP) and its allylic isomer dimethylallyl diphosphate (DMAPP) [57]. Many terpene volatiles are direct products of terpene biosynthesis enzymes, while some are derived through modifications and additional transformations of primary terpene skeletons, mainly via hydroxylation, dehydrogenation, acylation. For instance, hydroxylation of limonene results in the formation of trans-isopiperitenol and trans-carveol through different catalyzing enzymes and these hydroxylated terpenes are associated with characteristic flavor of certain PBPs [58,59]. Similarly, acetylation of certain terpenes like geraniol results in the formation of geranyl acetate, which has a pleasant fruity aroma and is found in many PBPs. Apart from fatty acid, amino acid and terpenoid pathways, carotenoid pathways represent another major class of volatiles in PBPs. Carotenoid derivatives mainly derived via the oxidation cleavage of carotenoids result in the formation of volatile apocarotenoid derivatives [60]. These volatiles contribute to the aroma of several vegetables and fruits [61].
萜类化合物是植物次生代谢产物中最大的一类，其中许多具有挥发性，对新鲜植物源性副产物的香气有重要贡献。半萜类（C5）、单萜类（C10）、倍半萜类（C15）、同萜类（C11和C16）以及某些二萜类（C20）具有较高的蒸气压，能够释放到周围大气中并挥发。所有萜类化合物都来源于通用的C5前体异戊烯基焦磷酸（Isopentenyl Diphosphate, IPP）及其烯丙基异构体二甲基烯丙基焦磷酸（Dimethylallyl Diphosphate, DMAPP）[57]。许多萜类挥发性物质是萜类生物合成酶的直接产物，而另一些则是通过初级萜类骨架的修饰和额外转化产生的，主要通过羟基化、脱氢、酰化等方式。例如，柠檬烯的羟基化通过不同的催化酶作用产生反式异胡椒醇和反式香芹醇，这些羟基化的萜类与某些植物源性副产物的特征风味有关[58,59]。同样地，某些萜类化合物如香叶醇的乙酰化会形成香叶基乙酸酯，它具有令人愉悦的果香，并存在于许多植物源性副产物（PBPs）中。除了脂肪酸、氨基酸和萜类途径外，类胡萝卜素途径也是PBPs中挥发性化合物的主要类别之一。类胡萝卜素衍生物主要通过类胡萝卜素的氧化裂解形成，进而产生挥发性的脱辅基类胡萝卜素衍生物[60]。这些挥发性化合物对多种蔬菜和水果的香气有重要贡献[61]。
In the past few years, several research studies have exploited metabolomics approaches to evaluate these diverse classes of aroma metabolites in a variety of fresh PBPs. We provide a representative summary for some of these aroma metabolites in selected fresh PBPs (Table 1). Studies have utilized different kinds of analytical platforms and extraction approaches to analyze chemical classes that contribute to the unique aroma and flavor of fresh PBPs, as summarized in Table 1.
Table 1. Aroma-related metabolites determined using different analytical platforms in fresh plant-based products (PBPs). A representative summary of recent research studies in this area.
| S.no | Metabolites Classes | PBP Type | Analytical Platform | References |
|---|---|---|---|---|
| 1 | Esters, alcohols, aldehydes, ketones, lactones, terpenoids, sulphur compounds | Melons (Cucumis melo L.) | GC-MS GC-O | [62] |
| 2 | Alcohols, acids, and carbonyl compounds, terpenoids and norisoprenoids, furan, phenols and phenylpropanoids, benzonoids, furans | Kiwifruit (Actinidia deliciosa) | GC-O | [52] |
| 3 | Monoterpene hydrocarbons and oxides, sesquiterpenes, aldehydes, alcohols, esters | Japanese citrus fruit (Citrus nagato-yuzukichi Tanaka) | GC-MS | [63] |
| 4 | Esters, alcohol, fatty acid esters, carboxylic acid esters | Pear fruit (Pyrus communis) | HRGC-C/P-IRMS | [64] |
| 5 | Esters, aldehydes, alcohol, benzenic derivatives, ethers | Ambul Banana (Musa acuminata, AAB) | GC-MS | [65] |
| 6 | Aldehydes and alcohols | Potato (Solanum tuberosum) | GC-FID | [66] |
| 7 | Aliphatic acids, aldehydes, alcohols, Oxygenated and nonoxygenated monoterpenes, phenolic derivatives, nor-isoprenes | Tomato (Solanum lycopersicum) | GC | [67] |
| 8 | C8-C9 unsaturated aldehydes and ketones | Oat (Avena sativa) | GC-MS, GC-O | [68] |
| 9 | Ketones, alcohols, esters, and heterocycle compounds | Intermediate wheatgrass (Thinopyrum intermedium) | GC-MS-O | [69] |
| 10 | Unsaturated hydrocarbons, carboxylic acid esters, phenol ethers | Rice (Oryza sativa) | GCGC-TOFMS | [70] |
| 11 | Alcohols, aldehydes, ketones, nitrogen-compounds, Straight- and branched-chain hydrocarbons | Jasmine brown rice (Oryza sativa) | GC-MS | [71] |
| 12 | Ketones, aldehydes, pyrazines, alcohols, aromatic hydrocarbons, furans, pyrroles, terpenes, and acids | Turkish Tombul Hazelnut (Corylus avellana L.) | GC-MS | [72] |
| 13 | Alcohols, aldehydes, esters, benzene derivates, linear hydrocarbons, ketones furans | Dark Black Walnut (Juglans nigra) | GCMS | [73] |
| 14 | Monoterpenes | Pistachio nuts (Pistacia vera L.) | GC-MS | [74] |
| 15 | Pyrazines, aldehydes, alcohols, ketones, esters, carbonic acids, furan derivatives, pyrroles, pyridines, pyran derivatives, hydrocarbons, phenols, sulphur compounds, lactones | Wheat flour bread (Triticum aestivum) | GC-MS | [75] |
| 16 | Aliphatic hydrocarbons, monoterpenes and such | Walnuts (Juglans regia L.) | GC–MS | [76] |
| S.no | 代谢物类别 | PBP类型 | 分析平台 | 参考文献 |
|---|---|---|---|---|
| 1 | 酯类、醇类、醛类、酮类、内酯类、萜类、含硫化合物 | 甜瓜（Cucumis melo L.） | GC-MS, GC-O | [62] |
| 2 | 醇类、酸类、羰基化合物、萜类和降异戊二烯类、呋喃类、酚类和苯丙素类、苯并类、呋喃类 | 猕猴桃（Actinidia deliciosa） | GC-O | [52] |
| 3 | 单萜烃和氧化物、倍半萜类、醛类、醇类、酯类 | 日本柑橘（Citrus nagato-yuzukichi Tanaka） | GC-MS | [63] |
| 4 | 酯类、醇类、脂肪酸酯类、羧酸酯类 | 梨果（Pyrus communis） | HRGC-C/P-IRMS | [64] |
| 5 | 酯类、醛类、醇类、苯衍生物、醚类 | 大蕉（Musa acuminata, AAB） | GC-MS | [65] |
| 6 | 醛类和醇类 | 马铃薯（Solanum tuberosum） | GC-FID | [66] |
| 7 | 脂肪酸、醛类、醇类、含氧和不含氧的单萜类、酚类衍生物、降异戊二烯类 | 番茄（Solanum lycopersicum） | GC | [67] |
| 8 | C8-C9不饱和醛类和酮类 | 燕麦（Avena sativa） | GC-MS, GC-O | [68] |
| 9 | 酮类、醇类、酯类和杂环化合物 | 中间型小麦草（Thinopyrum intermedium） | GC-MS-O | [69] |
| 10 | 不饱和烃类、羧酸酯类、酚醚类 | 水稻（Oryza sativa） | GCGC-TOFMS | [70] |
| 11 | 醇类、醛类、酮类、含氮化合物、直链和支链烃类 | 茉莉香米（Oryza sativa） | GC-MS | [71] |
| 12 | 酮类、醛类、吡嗪类、醇类、芳香烃类、呋喃类、吡咯类、萜类、酸类 | 土耳其Tombul榛子（Corylus avellana L.） | GC-MS | [72] |
| 13 | 醇类、醛类、酯类、苯衍生物、线性烃类、酮类、呋喃类 | 黑核桃（Juglans nigra） | GCMS | [73] |
| 14 | 单萜类 | 开心果（Pistacia vera L.） | GC-MS | [74] |
| 15 | 吡嗪类、醛类、醇类、酮类、酯类、碳酸类、呋喃衍生物、吡咯类、吡啶类、吡喃衍生物、烃类、酚类、含硫化合物、内酯类 | 小麦面粉面包（Triticum aestivum） | GC-MS | [75] |
| 16 | 脂肪烃类、单萜类 | 核桃Walnuts (Juglans regia L.) | GC-MS | [76] |
3.2.2. 味觉相关代谢物
Taste metabolites are quite closely linked with aroma metabolites. These metabolites are generally non-volatile in nature, and they contribute to the flavor profiles by enhancing the gustatory experience via accentuation of the volatile aroma metabolites. There are five kinds of taste perceptions, namely, sweet, salty, bitter, sour and umami. Different chemical classes of metabolites contribute to the taste sensation in PBPs. Sweetness generally comes from sugars, including sucrose, glucose, and fructose. The levels of these sugars are often influenced by genetic and environmental factors and are highly associated with the degree of ripening. A wide variety of PBPs, including fruits and vegetables, have varying levels of these sugars and their biosynthesis is genetically controlled and regulated. Sourness is derived from acids such as malic, citric, and oxalic acid. Bitterness is often associated with presence of polyphenols, alkaloids, tannins, certain glycosides, or peptides. For example, tannins provide the bitter notes and complements the flavor of several PBPs including tea and immature berries [77,78]. Among polyphenols, the taste of bitterness and tactile sensation are often associated with flavonoid phenols, including flavanols and flavonols. Some of the metabolites from these families such as proanthocyanidins or condensed tannins are abundant in wine and tea [79]. Salty and umami tastes are not common in PBPs. Among the taste sensations in PBPs, bitterness is the most complex, as structurally diverse chemical compounds/metabolites can elicit a single bitter taste, which suggests that multiple mechanisms are responsible for the perception and transduction of bitterness. It is also pertinent to note that small changes in chemical structure can transform bitter compounds to sweet or vice versa. Scientific evidence also suggests that bitter and sweet tastes, when present together, can enhance, or suppress each other [80]. In recent years, research initiatives have been directed towards evaluating metabolites that contribute to different taste sensations in a variety of fresh PBPs including fruits and vegetables. Among the taste-associated metabolites, polyphenols are studied extensively among a wide range of PBPs. Polyphenols are a ubiquitous class of non-volatile plant secondary metabolites and apart their sensory attributes, they are also known for their anti-inflammatory and other metabolic effects [81,82,83,84]. Polyphenols are biosynthesized by plants for chemical defense against predators and among them, class of flavonoids are associated with taste sensations in PBPs. Most of them contribute to a bitter taste in PBPs [77,78], but owing to their health benefits, several efforts are directed towards debittering the food products to increase its consumer acceptance [81]. This interest could also be partly responsible in the research impetus on understanding composition of polyphenols and their sensory attributes in PBPs. Representative research studies reporting diverse classes of polyphenols in various PBPs using various analytical platforms are summarized in Table 2.
味觉代谢物与香气代谢物联系十分密切。这些代谢物在本质上通常是不挥发的，它们通过增强挥发性香气代谢物来增强味觉体验，从而贡献风味谱。有五种味觉，即甜、咸、苦、酸和鲜味。不同化学类型的代谢物有助于PBPs的味觉。甜味通常来自糖，包括蔗糖、葡萄糖和果糖。这些糖的水平往往受到遗传和环境因素的影响，并与成熟程度高度相关。包括水果和蔬菜在内的多种PBPs含有不同水平的这些糖，其生物合成受遗传控制和调节。酸是由苹果酸、柠檬酸和草酸等酸产生的。苦味通常与多酚、生物碱、单宁、某些糖苷或肽有关。例如，单宁提供了苦味，并补充了包括茶和未成熟浆果在内的几种PBPs的风味[77,78]。在多酚中，苦味和触觉的味道往往与黄酮酚有关，包括黄烷醇和黄酮醇。这些家族的一些代谢物如原花青素或浓缩单宁在葡萄酒和茶中含量丰富[79]。咸味和鲜味在PBPs中并不常见。在PBPs的味觉感受中，苦味是最复杂的，因为不同结构的化合物/代谢物可以引起单一的苦味，这表明苦味的感知和转导有多种机制。同样值得注意的是，化学结构的微小变化可以将苦的化合物转变为甜的化合物，反之亦然。科学证据还表明，苦和甜的味道如果同时存在，会相互增强或抑制[80]。近年来，研究的主要方向是评估在包括水果和蔬菜在内的各种新鲜PBPs中有助于不同味觉感觉的代谢物。在与味觉相关的代谢物中，多酚在广泛的PBPs中被广泛研究。多酚是一种普遍存在的非挥发性植物次生代谢物，除了其感官特性外，它们还具有抗炎和其他代谢作用[81,82,83,84]。多酚是由植物生物合成的，用于抵御捕食者的化学防御，其中类黄酮与PBPs的味觉有关。它们中的大多数导致PBPs中有苦味[77,78]，但由于它们对健康有益，因此有几项努力旨在通过扣除食品来提高消费者的接受度[81]。这种兴趣也在一定程度上推动了对PBPs中多酚的组成及其感官特性的研究。表2总结了使用不同分析平台的不同PBPs中不同类别的多酚的代表性研究。
Table 2. Taste-related metabolites determined using different analytical platforms in fresh PBPs. A representative summary of recent research studies in this area.
表2。使用不同的分析平台测定新鲜PBPs中的味道相关代谢物。该领域的代表性研究综述。
| S.no | Metabolites Classes | PBP Type | Analytical Platform | References |
|---|---|---|---|---|
| 1 | Hydroxycinnamic acid glycosides, quercetin glycoside derivatives | Mountain papaya (Vas concellea pubescens) | LC-DAD-MS | [82] |
| 2 | Phenolics, myricetin hexoside, myricetin deoxyhexoside derivatives, quercetin hexoside, quercetin deoxyhexoside derivatives | Bayberries (Myrica rubra Sieb. et Zucc) | HPLC-DAD-ESI-MS | [83] |
| 3 | Simple phenolic and hydroxycinnamoylquinic acids and flavons, flavonols, flavanone and dihydrochalcone derivatives | Tomato (Solanum lycopersicum) | HPLC–ESI-QTOF | [84] |
| 4 | Anthocyanidins, aliphatic or aromatic acylated groups, sugar moieties | Eggplant (Solanum melongena); red leaf lettuce (Lactuca sativa); Pistachio (Pistacia vera) and others | HPLC-DAD-ESI-MS-MS | [85] |
| 5 | Proanthocyanidins, phenolic acids | Barley (Hordeum vulgare) | HPLC-DAD-MS | [86] |
| S.no | 代谢产物类别 | 植物基产品(PBP)类型 | 分析平台 | 参考文献 |
|---|---|---|---|---|
| 1 | 羟基肉桂酸糖苷、槲皮素糖苷衍生物 | 山木瓜（Vasconcellea pubescens） | 液相色谱-二极管阵列检测-质谱（LC-DAD-MS） | [82] |
| 2 | 酚类、杨梅素己糖苷、杨梅素脱氧己糖苷衍生物、槲皮素己糖苷、槲皮素脱氧己糖苷衍生物 | 杨梅（Myrica rubra Sieb. et Zucc） | 高效液相色谱-二极管阵列检测-电喷雾电离质谱（HPLC-DAD-ESI-MS） | [83] |
| 3 | 简单酚类、羟基肉桂酰奎尼酸及黄酮类、黄酮醇类、黄烷酮类和二氢查尔酮类衍生物 | 番茄（Solanum lycopersicum） | 高效液相色谱-电喷雾电离四极杆飞行时间质谱（HPLC–ESI-QTOF） | [84] |
| 4 | 花青素、脂族或芳香族酰化基团、糖基 | 茄子（Solanum melongena）、红叶莴苣（Lactuca sativa）、开心果（Pistacia vera）等 | 高效液相色谱-二极管阵列检测-电喷雾电离串联质谱（HPLC-DAD-ESI-MS-MS） | [85] |
| 5 | 原花青素、酚酸 | 大麦（Hordeum vulgare） | 高效液相色谱-二极管阵列检测-质谱（HPLC-DAD-MS） | [86] |
Currently, for flavor-associated metabolite profiling, several extraction techniques and analytical platforms are employed to capture the analytes of interest, which are discussed in the next section. The number of studies reported in this area are progressively increasing with the advent of rapidly evolving analytical platforms, curated databases, automated sample, and liquid handling systems. There is a scientific cognizance about the potential of metabolomics for this growing field, although it has not been widely adopted for routine quality assessment due to a variety of factors including sampling considerations and technical challenges.
目前，在风味相关代谢物分析方面，采用了多种提取技术和分析平台来捕获感兴趣的分析物，这将在下一节中详细讨论。随着快速发展的分析平台、经过整理的数据库、自动化样品处理和液体处理系统的出现，该领域的研究报告数量正在逐渐增加。尽管科学界认识到代谢组学在这一新兴领域的潜力，但由于采样考虑和技术挑战等多种因素，它尚未被农业食品部门和监管机构广泛采用于常规质量评估。
3.3 代谢组学的采样和其他考虑因素
As detailed in the earlier Section 3.2, the use of metabolomics in evaluating flavor attributes of fresh PBPs is gaining considerable interest in the scientific community. However, its widespread adoption by agri-food related sectors and regulatory agencies would require streamlining (i) sampling protocols; (ii) pre-concentration and extraction procedures; and (iii) analytical platforms and approaches. We describe below these three important points for consideration in order to successfully employ metabolomics for evaluating flavor-associated metabolites in fresh PBPs.
如之前第3.2节所述，代谢组学在评估新鲜植物基产品（PBPs）的风味特性方面正受到科学界的广泛关注。然而，要使其在农业食品部门和监管机构中得到广泛应用，需要优化以下三个方面：（i）采样协议；（ii）预浓缩和提取程序；（iii）分析平台与方法。在成功应用代谢组学来评估新鲜植物基产品（PBPs）中的风味相关代谢物时，分析平台与方法是另一个至关重要的考虑因素。
(i)Sampling protocols: As the biosynthesis of flavor-associated metabolites in fresh PBPs is often influenced by several genetic and environmental factors [87], sampling protocols are a critical step in determining true readouts. Environmental factors including farm/management practices, degree of maturity and post-harvest handling will affect the abundance of these bioactive metabolites in the fresh PBPs [88]. Apart from the environmental factors, the nature of these metabolites and their chemistries will also influence the sampling protocols and operational procedures as some metabolites are found in bound form, while others are released only upon tissue disruption.
(i) 采样协议：由于新鲜植物基产品（PBPs）中风味相关代谢物的生物合成往往受到多种遗传和环境因素的影响[87]，因此采样协议是确定真实结果的关键步骤。环境因素，包括农场/管理实践、成熟度和采后处理，都会影响这些生物活性代谢物在新鲜PBPs中的含量[88]。除了环境因素外，这些代谢物的性质和化学结构也会影响采样协议和操作程序，因为一些代谢物以结合形式存在，而其他代谢物则仅在组织破坏时释放。
For instance, certain aroma metabolites are only released upon cell disruption when enzymes and their corresponding substrates interact [89]. However, some aroma compounds are bound to sugars as glycosides or glucosinolates [90] and odorous aglycones could be released from the sugar moiety during post-harvest stages. Hence, it is pertinent to adopt sampling protocols that can capture the metabolites of interest in a PBP.
例如，某些香气代谢物仅在细胞破坏时酶与其相应底物相互作用时释放[89]。然而，一些香气化合物以糖苷或硫代葡萄糖苷的形式与糖结合[90]，在采后阶段糖基部分可能释放出有气味的配基。因此，采用能够捕获PBP中感兴趣代谢物的采样协议至关重要。
To simplify, protocols can be standardized for certain families of PBPs, which are known to have similar metabolite classes. For instance, members of Brassica genus (such as broccoli, cabbage, kale) are known to contain glucosinolates (GSLs, sulphur rich secondary metabolites) contributing to their bitter taste and unique aroma [91], and sampling protocols can be standardized across members of this genus for efficient capture of GSLs. Alternatively, protocols can be standardized across different PBPs for the same families of metabolites, such as benzenoids, alcohols and esters.
为了简化操作，可以对具有相似代谢物类别的某些PBP家族制定标准化的采样协议。例如，十字花科属（如西兰花、卷心菜、羽衣甘蓝）的植物以含有硫代葡萄糖苷（GSLs，富含硫的次级代谢物）而闻名，这些物质为其提供了苦味和独特香气[91]，因此可以对该属内的成员制定标准化的采样协议，以有效捕获GSLs。另外，也可以针对不同PBPs中相同类别的代谢物（如苯环化合物、醇类和酯类）制定标准化的采样协议。
Sampling time-points are equally important, as it is known that PBPs have varying levels and kinds of metabolites at different growth and maturity stages. For instance, it is known that the growth stage has an influence on specific GSLs composition and content among members from Brassica genus [92]. Similarly, anthocyanins are also regulated differently at different developmental and ripening stages [93].
采样时间点同样重要，因为已知PBPs在不同生长和成熟阶段具有不同水平和种类的代谢物。例如，已知生长阶段会影响十字花科属成员中特定GSLs的组成和含量[92]。因此，在选择采样时间点时，应充分考虑PBPs的生长和成熟周期，以确保捕获到最具代表性的风味相关代谢物。同样地，花青素（Anthocyanins）在不同发育和成熟阶段也受到不同的调控[93]。
(ii)Pre-processing and extraction procedures: Apart from sampling protocols, the choice and selection of pre-processing and extraction procedures are equally important due to the thermolabile nature and trace concentrations of these metabolites in fresh PBPs. Extraction procedures largely depend on (i) the nature and chemistry of metabolites (polar/non-polar; volatile/non-volatile); (ii) the thermal stability and sensitivity; and (iii) their occurrence and subsequent release. A variety of methods are prescribed for the extraction and characterization of metabolites linked to the flavor properties of fresh PBPs.
(ii) 预处理和提取程序：除了采样协议外，选择和确定预处理和提取程序对于新鲜PBPs中这些代谢物的分析同样至关重要，因为这些代谢物在新鲜PBPs中具有热不稳定性和痕量浓度的特点。提取程序主要依赖于（i）代谢物的性质和化学结构（极性/非极性；挥发性/非挥发性）；（ii）热稳定性和敏感性；以及（iii）它们的存在和随后的释放。针对与新鲜PBPs风味特性相关的代谢物的提取和表征，已经规定了多种方法。
Due to the volatile nature of a variety of aroma-metabolites, headspace analyses involving the gas phase in equilibrium with PBPs are commonly utilized for flavor analyses. The headspace-solid phase microextraction (HS-SPME) is notable for being sensitive, solvent-free and has been successfully employed for flavor extraction of fresh PBPs [94,95]. SPME fiber coatings with different polarities are often required for effective capture of aroma-metabolites with varying chemistries and affinities [96]. However, the limitations of SPME have been pointed out for the quantitation of certain volatile classes of aroma-metabolites [97].
由于多种香气代谢物具有挥发性，因此常与PBPs处于平衡状态的气相进行顶空分析，以进行风味分析。顶空固相微萃取（HS-SPME）因其灵敏度高、无需溶剂的特点而被广泛应用于新鲜PBPs的风味提取[94,95]。为了有效捕获具有不同化学性质和亲和力的香气代谢物，通常需要具有不同极性的SPME纤维涂层[96]。然而，SPME在定量某些挥发性香气代谢物方面存在局限性[97]。
Other techniques used for capturing volatile and semi-volatile metabolites from PBPs are solvent-less enrichment techniques, such as stir bar sorptive extraction (SBSE) [98] and headspace sorptive extraction, (HSSE) wherein stir bar (covered in polysiloxane) is exposed to the sample (either in gaseous or liquid sample media). After extraction, compounds are thermally desorbed before analyses. Extraction techniques assisted by solvents and thermal distillation have been utilized for certain classes of organosulphur metabolites. Steam distillation (SD), simultaneous distillation and solvent extraction (SDE), and solid-phase trapping solvent extraction (SPTE) are used to characterize sulphur-rich aroma-metabolites in certain fresh PBPs such as garlic and onion [98]. Similarly, liquid–liquid extraction (LLE) and solvent-assisted flavor evaporation (SAFE) are used as preferred extraction techniques for furan derivatives that contribute to flavor profiles of certain PBPs [99]. It is pertinent to note here that several extraction techniques have been evaluated based on trapping, capture and dissolution of metabolites to enhance metabolite coverage from plant matrices.
除了溶剂提取方法外，从植物源挥发性和半挥发性代谢物（PBPs）中捕获这些物质还采用了无溶剂富集技术，如搅拌棒吸附萃取（Stir Bar Sorptive Extraction, SBSE）[98]和顶空吸附萃取（Headspace Sorptive Extraction, HSSE）。在SBSE中，覆盖有聚硅氧烷的搅拌棒被暴露于样品中（样品可以是气态或液态介质）。提取后，化合物在进行分析前会经过热解析。对于某些类别的有机硫代谢物，则采用了溶剂辅助和热蒸馏的提取技术。蒸汽蒸馏（Steam Distillation, SD）、同时蒸馏萃取（Simultaneous Distillation and Solvent Extraction, SDE）和固相捕集溶剂萃取（Solid-Phase Trapping Solvent Extraction, SPTE）等技术被用于表征大蒜、洋葱等某些新鲜PBPs中富含硫的芳香代谢物[98]。类似地，液液萃取（Liquid-Liquid Extraction, LLE）和溶剂辅助风味蒸发（Solvent-Assisted Flavor Evaporation, SAFE）被用作提取某些PBPs中贡献风味轮廓的呋喃衍生物的首选技术[99]。这里需要特别指出的是，已经根据代谢物的捕获、收集和溶解来评估了几种提取技术，以从植物基质中增强代谢物的覆盖范围。
(iii)Analytical platforms and approaches: As seen in the previous section, analytical approaches and platforms are also dependent on the metabolites of interest. GC-O or GC-MS (gas-chromatography-olfactory/gas-chromatography mass-spectrometry) are routinely employed for the detection of aroma- and odor-producing metabolites [63,65,69]. In olfactometric techniques, the nose is used as a GC detector. The GC system can be set up with the column split, and a portion of the effluent goes to the sniffing port and the remainder is fed to the GC detector (FID or an MS detector). GC-O produces an aromagram, which lists the odor character of each peak in a GC run. This method is dependent on the analyst and his sensory perception and, hence, this is a powerful technique which can bridge the conventional sensory evaluation and panel tests with more quantitative information. GC-O can be employed to distinguish between characteristic and off-odors in fresh PBPs, which will assist in quality assessment in terms of food safety and consumer acceptability. While GC-O is more to detect odor and aroma-metabolites, when it is paired with MS detector, it can be used as an identification tool to characterize and quantitate certain metabolites of interest [100]. Other instrumental methods used include NMR and LC-MS. LC-MS platforms are mainly restricted for non-volatile classes of metabolites [82,83,84] such as organic acids, sugars and certain polyphenols which contribute to characteristic taste notes in fresh PBPs.
（iii）分析平台和方法：正如前一节所看到的，分析方法和平台也取决于感兴趣的代谢物。气相色谱-嗅觉分析（GC-O）或气相色谱-质谱联用（GC-MS）常用于检测产生香气和异味的代谢物[63,65,69]。在嗅觉测定技术中，鼻子被用作气相色谱的检测器。气相色谱系统可以设置成分流柱，一部分流出物进入嗅探口，其余部分送入气相色谱检测器（FID或MS检测器）。GC-O会产生一个气味图，列出气相色谱运行中每个峰的气味特征。这种方法依赖于分析人员及其感官感知，因此，这是一种强大的技术，可以将传统的感官评估和小组测试与更多定量信息相结合。GC-O可用于区分新鲜PBPs中的特征气味和异味，这将有助于食品安全和消费者接受度方面的质量评估。虽然GC-O主要用于检测气味和香气代谢物，但当它与MS检测器结合时，可用作表征和定量某些感兴趣代谢物的鉴定工具[100]。其他使用的仪器方法包括核磁共振（NMR）和液相色谱-质谱联用（LC-MS）。LC-MS平台主要局限于非挥发性代谢物类别[82,83,84]，如有机酸、糖类和某些多酚，这些物质对新鲜PBPs的特征风味有贡献。
Lately, biosensors (such as electronic noses and electronic tongues) based on pattern recognition of flavor and aroma metabolites have been developed that can crudely mimic the human taste and olfactory receptors and their communication with the human brain [101,102]. These electronic noses (e-noses) and electronic tongues (e-tongues) do not generate information on sample composition but provide a digital fingerprint through pattern recognition. These devices are capable of mimicking human smell and taste sensors based on previous exposure leading to pattern recognition through neural networks. This is useful for routine post-harvest quality assessment of fresh PBPs to evaluate produce for optimum flavor attributes. For instance, it can be used to evaluate effects on storage conditions on quality of fresh PBPs [103]. Recently, e-noses have been utilized for diverse PBPs (especially fruits and vegetables) to evaluate volatile metabolites that are associated with flavor and/or post-harvest quality of PBPs [104,105,106]. Most often, these sensors have been used in combination with GC-O/ GC-MS techniques with or without sensory analyses, as summarized in Table 3.
近年来，基于风味和香气代谢物模式识别的生物传感器（如电子鼻和电子舌）得到了发展，这些传感器能够粗略地模拟人类味觉和嗅觉受体及其与大脑的通讯[101,102]。这些电子鼻（e-noses）和电子舌（e-tongues）不产生关于样品组成的信息，但通过模式识别提供数字指纹。这些设备能够基于先前的暴露来模拟人类的嗅觉和味觉传感器，并通过神经网络进行模式识别。这对于新鲜PBPs的日常收获后质量评估非常有用，可以评估产品的最佳风味特性。例如，它可以用于评估储存条件对新鲜PBPs质量的影响[103]。最近，电子鼻已被用于各种PBPs（尤其是水果和蔬菜）中，以评估与风味和/或收获后质量相关的挥发性代谢物[104,105,106]。这些传感器通常与GC-O/GC-MS技术结合使用，无论是否进行感官分析，如表3所示。
Table 3. Representative summary of recent studies reporting application of e-nose with or without other analytical platforms to evaluate flavor-associated metabolites in fresh PBPs.
表3. 近期研究报告中将电子鼻与其他分析平台结合使用或单独使用以评估新鲜PBPs中风味相关代谢物的代表性总结。
| Metabolites Class | PBP Used | Analytical Platform | Reference |
|---|---|---|---|
| Aldehydes, Alcohols and ketones | Apricots (Prunus armeniaca) | GC; e-nose; sensory analysis | [104] |
| Alcohols, terpene, aromatic hydrocarbons, aliphatic hydrocarbons | Mango (Mangifera indica) | GC; e-nose | [105] |
| Aromatic and aliphatic hydrocarbons | Blueberry (Vaccinium corymbosum) | e-nose | [106] |
| Alcohol, ester, aldehyde, terpenes | Grapes (Vitis vinifera) | GC; e-nose | [107] |
| Aldehydes, Alcohol, ketones | Tomato (Lycopersicon esculentum) | e-nose | [108] |
| Aldehydes, ketones, sulphur compounds, alkanes, terpenes, alcohols | Pineapple (Ananus Comosus) | e-nose | [109] |
| Acids, esters, Aldehydes, ketones, aliphatic and aromatic hydrocarbons | Citrus | GC-MS; e-nose | [110] |
| Ester, carboxylic acids, alcohols, Aldehydes, monterpenes | White and red fleshed peach (Prunus persica) | GC-MS; e-nose | [111] |
| Carboxylic acid, ester, alcohol, | Snake fruit (Salacca zalacca) | GC-MS; e-nose | [112] |
| Pyruvic acid | Onion (Allium cepa) | HPLC; e-nose | [113] |
| 物性生物产品（PBP） | 分析平台 | 参考文献 | |
|---|---|---|---|
| 醛类、醇类和酮类 | 杏（Prunus armeniaca） | 气相色谱（GC）；电子鼻（e-nose）；感官分析 | [104] |
| 醇类、萜烯、芳香烃、脂肪烃 | 芒果（Mangifera indica） | 气相色谱（GC）；电子鼻（e-nose） | [105] |
| 芳香烃和脂肪烃 | 蓝莓（Vaccinium corymbosum） | 电子鼻（e-nose） | [106] |
| 醇类、酯类、醛类、萜烯 | 葡萄（Vitis vinifera） | 气相色谱（GC）；电子鼻（e-nose） | [107] |
| 醛类、醇类、酮类 | 番茄（Lycopersicon esculentum） | 电子鼻（e-nose） | [108] |
| 醛类、酮类、硫化物、烷烃、萜烯、醇类 | 菠萝（Ananas comosus） | 电子鼻（e-nose） | [109] |
| 酸类、酯类、醛类、酮类、脂肪烃和芳香烃 | 柑橘类 | 气相色谱-质谱联用（GC-MS）；电子鼻（e-nose） | [110] |
| 酯类、羧酸类、醇类、醛类、单萜烯 | 白肉和红肉桃（Prunus persica） | 气相色谱-质谱联用（GC-MS）；电子鼻（e-nose） | [111] |
| 羧酸类、酯类、醇类 | 蛇皮果（Salacca zalacca） | 气相色谱-质谱联用（GC-MS）；电子鼻（e-nose） | [112] |
| 丙酮酸 | 洋葱（Allium cepa） | 高效液相色谱（HPLC）；电子鼻（e-nose） | [113] |
To summarize, reliable and credible estimations of metabolites corresponding to flavor-related sensory attributes in PBPs require careful sampling strategies, thorough pre-processing and extraction procedures followed by robust analytical platforms.
总结来说，为了对植物性生物产品（PBPs）中与风味相关的感官属性进行可靠且可信的代谢物估算，需要精心的采样策略、彻底的预处理和提取程序，以及强大的分析平台。
3.4 植物性生物产品的代谢组学与质量评估
The quality of the fresh PBPs in terms of their nutritive value and flavor profiles is essentially driven by their biochemical composition. Biochemical composition is also a key factor in determining other important properties of fresh PBPs such as shelf life, nutritional stability, and economic value. New tools are required to define “quality” to include more quantitative information about the biochemical composition of food, as consumers’ expectations continue to grow with respect to food quality and safety [114]. Meanwhile, current quality assessment relies heavily on classical methodologies which can largely inform general consumer acceptability, but they lack the ability to provide detailed information on biochemical composition or metabolites that correspond to unique flavors of fresh PBPs.
新鲜PBPs的营养价值和风味特征主要由其生化组成决定。生化组成也是决定新鲜PBPs其他重要属性（如保质期、营养稳定性和经济价值）的关键因素。随着消费者对食品质量和安全性的期望不断提高，需要新的工具来定义“质量”，以包含更多关于食品生化组成的定量信息[114]。然而，目前的质量评估主要依赖于传统方法，这些方法虽然能在很大程度上反映一般消费者的接受度，但缺乏提供关于新鲜PBPs独特风味对应生化组成或代谢物的详细信息的能力。
To this end, metabolomics can pave the way for decoding the composition and nature of flavor-associated metabolites in fresh PBPs, which can open avenues for further improvements of PBPs [115,116]. As such, the scope of metabolomics in this domain extends beyond just quality assessment for flavor-associated metabolites; it can be further utilized for (i) biomarker-detection related to food safety; (ii) development of new crops with better genetic traits; (iii) determination of food contaminants/adulterants; and (iv) new investigations on food bioactivities [117,118,119].
为此，代谢组学可以为解码新鲜PBPs中风味相关代谢物的组成和性质铺平道路，从而为PBPs的进一步改进开辟途径[115,116]。因此，代谢组学在这一领域的范围不仅限于风味相关代谢物的质量评估；它还可以进一步用于（i）食品安全相关的生物标志物检测；（ii）开发具有更好遗传性状的新作物；（iii）确定食品污染物/掺假物；以及（iv）对食品生物活性的新研究[117,118,119]。这些应用展示了代谢组学在提升PBPs质量、安全性和市场价值方面的巨大潜力。
Although a distinct research area on food metabolomics has been established in the scientific community in relation to the application of metabolomics in food system processes [119,120] from farm to consumers, its widespread adoption comes with certain unparalleled challenges (as discussed in Section 3.3). These challenges are often compounded by the nature of the food metabolome, which is complex and variable in nature as thousands of metabolites are present in fresh PBPs with varying polarities and chemistries [121]. Measuring and quantifying the metabolome that best represents the flavor profiles of fresh PBPs can pose analytical challenges as it may not be possible to detect all of them in a single analysis. To this end, utilizing multiple analytical techniques and approaches is often recommended in food metabolomics which can complement each other and provide a wider coverage [122,123].
尽管在科学界中已经建立了与食品系统中从农场到消费者过程中代谢组学应用相关的食品代谢组学这一独特研究领域[119,120]，但其广泛应用仍面临一些无与伦比的挑战（如第3.3节所述）。这些挑战往往因食品代谢组的复杂性和可变性而加剧，因为新鲜PBPs中存在数以千计的代谢产物，它们具有不同的极性和化学性质[121]。测量和量化最能代表新鲜PBPs风味特征的代谢组可能会带来分析挑战，因为可能无法在一次分析中检测到所有代谢物。为此，在食品代谢组学中通常推荐使用多种分析技术和方法，它们可以相互补充，提供更广泛的覆盖范围[122,123]。
In addition to this, the food matrix of PBPs will also affect the detection and quantification of compounds that are present at very low concentrations in fresh PBPs or are present in bound forms and unstable forms (as discussed in Section 3.3). Apart from these analytical and sampling-related hurdles, there are certain challenges at downstream data processing and integration with current quality assessment methodologies, and these will be discussed in the next section.
除了这一点外，PBPs的食品基质也会影响在新鲜PBPs中以极低浓度存在或以结合形式和不稳定形式存在的化合物的检测和量化（如第3.3节所述）。除了这些分析和采样相关的障碍外，在下游数据处理和与当前质量评估方法的集成方面也存在某些挑战，这些将在下一节中讨论。
4. 新鲜PBPs的风味评估：未来方向
As discussed in Section 3.3 and Section 3.4, there is an immediate need to extend and complement the current repertoire of sensory-based and coarse instrumental estimations to evaluate the flavor- associated metabolites in fresh PBPs. This need is fueled by several socio-economic and psychological factors that have been discussed in the earlier section (Section 1.1 and Section 1.2). Against this background, the current quality assessment methodologies for fresh PBPs will need to be more inclusive of systematic metabolic estimations for flavor attributes in fresh PBPs. Metabolomics can prove to be a valuable tool in this regard, however, utilizing this technique with other routine quality assessment methodologies will require careful considerations at multiple levels. Additionally, it is pertinent to note here that although metabolomics can provide useful biochemical insights about flavor-associated metabolites in PBPs, it cannot provide any information on the human perception of food flavors, which is often influenced by physiological, psychological, genetics and other associated socio-cultural factors [124,125,126]. These factors contribute to the inter-individual variation and cause stark differences in perception of these metabolites by various population groups. To account for these differences, sensory-based tests will remain critical to obtain holistic understanding on consumer acceptance and behavior.
正如第3.3节和第3.4节所讨论的，目前迫切需要扩展和补充基于感官和粗略仪器评估的现有方法，以评估新鲜PBPs中与风味相关的代谢物。这一需求受到前几节（第1.1节和第1.2节）中讨论的多个社会经济和心理因素的推动。在此背景下，当前对新鲜PBPs的质量评估方法需要更加全面地纳入对风味特性的系统性代谢评估。代谢组学在这方面可以证明是一个有价值的工具，然而，将这一技术与其他常规质量评估方法结合使用时，需要在多个层面上进行仔细考虑。此外，值得注意的是，尽管代谢组学可以提供关于PBPs中与风味相关的代谢物的有用生化见解，但它无法提供关于人类对食物风味感知的任何信息，这种感知往往受到生理、心理、遗传和其他相关社会文化因素的影响[124,125,126]。这些因素导致了个体差异，并导致不同人群对这些代谢物的感知存在显著差异。为了解释这些差异，基于感官的测试对于全面了解消费者的接受度和行为仍然至关重要。
To harness the potential of metabolomics for evaluating flavor-associated metabolites in PBPs, it is important to keep in mind that both pre and post-harvest procedures including the extraction and analysis of metabolites will have great bearing on the observed results (Figure 1). In order to complement the existing sensory-based and instrumental measurements, a clear interface and seamless integration has to be established between the pre and post-harvest procedure in order to s to ensure aa smooth workflow for rapid quality assessment of fresh PBPs (Figure 2).
为了利用代谢组学评估PBPs中与风味相关的代谢物的潜力，重要的是要记住，包括代谢物提取和分析在内的采收前和采收后程序都将对观察到的结果产生重大影响（见图1）。为了补充现有的基于感官和仪器的测量方法，必须在采收前和采收后程序之间建立一个清晰的界面和无缝集成，以确保为新鲜PBPs的快速质量评估提供顺畅的工作流程（见图2）。
Figure 1. Considerations for utilizing metabolomics for evaluating flavor-associated metabolites in fresh PBPs. Here, we describe the various factors that will have an effect on metabolite estimations in fresh PBPs.
图1. 利用代谢组学评估新鲜PBPs中与风味相关的代谢物的考虑因素。 在此，我们描述了各种将影响新鲜PBPs中代谢物估计的因素。
Figure 2. Framework for integrating metabolomics with current state-of-the-art technologies for the organoleptic evaluation of fresh PBPs. While physicochemical measurements are coarse-scale estimations, metabolomics and sensory-based tests serve as fine-scale estimations to achieve a holistic flavor profiling of fresh PBPs. Data integration platforms would play a crucial role to achieve seamless data stitching for meaningful insights.
图2。将代谢组学与当前最先进的技术相结合的框架，用于新鲜PBPs的感官评估。虽然物理化学测量是粗略的估计，但代谢组学和基于感官的测试可以作为精细的估计，以实现新鲜PBPs的整体风味分析。数据集成平台将在实现无缝数据拼接以获得有意义的见解方面发挥关键作用。
Integrating metabolomics with the current state-of-the-art technologies for quality assessment will require synchronized efforts at several points—all the way from data collection to data analyses. To maximize the potential of metabolomics approaches, data collation from various platforms along with careful data interpretation will undoubtedly play a key role. This can lead to several other technical challenges, depending upon the category of PBPs in question, and the nature of information required. Some of the technical challenges could be related to the availability of (i) the right instrumental platform or extraction protocols for metabolites of interest; (ii) reference databases and spectral libraries for matching interesting metabolic features in PBPs; and (iii) the complete metabolome or databank for the plant source in question.
将代谢组学与当前最先进的质量评估技术相结合，需要在从数据收集到数据分析的各个方面同步努力。为了最大限度地发挥代谢组学方法的潜力，来自各个平台的数据整理以及仔细的数据解释无疑将发挥关键作用。这可能会导致其他一些技术挑战，这取决于所讨论的pbp的类别和所需信息的性质。一些技术挑战可能与(i)合适的仪器平台或感兴趣的代谢物提取方案的可用性有关;(ii)参考数据库和谱库，用于匹配PBPs中有趣的代谢特征;(iii)有关植物来源的完整代谢组或数据库。
Owing to the rapid developments in extraction and analytical methodologies, several options are available to analyze metabolites with varying chemistries, thereby increasing the global metabolite coverage. With these developments, the first technical hurdle can be conquered with few rounds of trials and optimization. However, the second and third technical challenges pose the greatest difficulty, not just for the agri-food domain, but also for other scientific domains, as a lack of reference databases and metabolome information makes it difficult to interpret the data and obtain meaningful insights. Lately, several curated databases have been made available in the plant domain specifically for diverse phytochemicals and bioactive metabolites to help the research community [127,128]. As the plant metabolome is highly diverse, with thousands of metabolites, it presents a laborious and technically challenging task to annotate every single metabolite. To overcome this challenge, efforts can be strategized towards the identification of candidate/marker metabolic members from different classes that can best represent the specific PBPs. This would eliminate the need to identify each metabolite and, at the same time, will serve as reference for rapid screening of PBPs based on presence of certain key metabolite classes. The choice and selection of such metabolite classes would depend upon the type of PBPs and their ultimate end-use. Monitoring glucosinolates (sulphur containing metabolites) in members from Brassica genus can be a classical example for this, as these metabolites are (i) unique to Brassica family members; (ii) associated with the flavor attributes of these plant types; and (iii) known for their human health benefits. Similarly, eucalyptols (cyclic ether, monoterpenoids) are unique to members of the Myrtaceae family and they are known for imparting a mint-like aroma and spicy taste notes. Other examples include PBPs from Amaryllidaceae that contain S-alk(en)yl-l-cysteine sulfoxides. Another way to approach this challenge will be to generate reference metabolic fingerprints of PBPs and utilize machine learning-based algorithms for pattern recognitions and high-throughput screening. This approach relies on the premise that if sampling, extraction and analytical conditions are kept the same, metabolic fingerprint from two PBPs samples of same type would be identical or similar to a large extent. However, this approach should be utilized as a fast screen and for more quantitative information, in-depth analyses are recommended. Apart from these technical challenges, a systematic method to integrate and collate the data from various platforms is warranted to maximize the potential of multi-platforms in the sensory evaluation of fresh PBPs.
由于提取和分析方法的迅速发展，有几种选择可用于分析具有不同化学性质的代谢物，从而增加了全球代谢物的覆盖率。有了这些发展，第一个技术障碍可以通过几轮试验和优化来克服。然而，第二和第三个技术挑战带来了最大的困难，不仅对农业食品领域，而且对其他科学领域也是如此，因为缺乏参考数据库和代谢组信息使得难以解释数据并获得有意义的见解。最近，在植物领域专门为各种植物化学物质和生物活性代谢物建立了几个数据库，以帮助研究界[127,128]。由于植物代谢组具有高度多样性，有数千种代谢物，因此对每一种代谢物进行注释是一项艰苦且具有技术挑战性的任务。为了克服这一挑战，可以从不同的类别中确定最能代表特定PBPs的候选/标记代谢成员。这将消除识别每种代谢物的需要，同时，将作为基于某些关键代谢物类别的PBPs快速筛选的参考。这些代谢物类别的选择将取决于PBPs的类型及其最终用途。监测来自芸苔属成员的硫代葡萄糖苷(含硫代谢物)可能是一个典型的例子，因为这些代谢物是(i)芸苔属成员所特有的;(ii)与这些植物类型的风味属性有关;(三)以对人体健康有益而闻名。类似地，桉树精油(环醚，单萜类)是桃金娘科成员所特有的，它们以赋予薄荷般的香气和辛辣的味道而闻名。其他的例子包括来自Amaryllidaceae的PBPs，它含有S-alk(en)yl-l-半胱氨酸亚砜。解决这一挑战的另一种方法是生成PBPs的参考代谢指纹，并利用基于机器学习的算法进行模式识别和高通量筛选。该方法的前提是，在取样、提取和分析条件相同的情况下，同一类型的两个PBPs样品的代谢指纹在很大程度上是相同或相似的。但是，这种方法应该用作快速筛选，并建议进行深入分析以获得更多定量信息。除了这些技术挑战之外，需要一种系统的方法来整合和整理来自不同平台的数据，以最大限度地发挥多平台在新鲜PBPs感官评估中的潜力。
A significant improvement has been achieved in recent years in data integration and chemometrics pipelines, making it easier to obtain integrated biological outputs from different platforms. In recent years, numerous tools have been developed, written in most used programming languages such as Python, R, and Matlab® to aid in metabolomics data curation and management [127]. Additionally, several platforms are being made available for sharing scripts and workflows through open-access repositories (Github, StackOverflow). Interactive and intuitive data integration workflows are being developed that have adopted artificial intelligence (AI) and machine learning (ML) approaches [129,130]. Data integration platforms that combine e-noses and e-tongues with high resolution MS and analytical instrumentation could be a way to logically bridge current gaps between human-based sensory tests and metabolic estimations. Although these artificial sensory techniques cannot integrate taste and smell as can be done by the human sensory system, they can generate reliably consistent data in a high-throughput format. With the availability of the requisite computational power, it is possible to integrate such modular information from these artificial sensors to obtain meaningful insights [131,132].
近年来，在数据集成和化学计量学管道方面取得了重大进展，使得从不同平台获得综合生物输出变得更加容易。近年来，已经开发了许多工具，用最常用的编程语言(如Python、R和Matlab®)编写，以帮助代谢组学数据的管理和管理[127]。此外，有几个平台可以通过开放访问存储库(Github, StackOverflow)共享脚本和工作流。采用人工智能(AI)和机器学习(ML)方法的交互式和直观的数据集成工作流程正在开发[129,130]。将电子鼻和电子舌与高分辨率质谱和分析仪器相结合的数据集成平台可能是一种从逻辑上弥合目前基于人类的感官测试和代谢估计之间差距的方法。虽然这些人工感官技术不能像人类感官系统那样整合味觉和嗅觉，但它们可以以高通量格式生成可靠一致的数据。有了必要的计算能力，就有可能整合这些人工传感器的模块化信息，以获得有意义的见解[131,132]。
This will be particularly resourceful for innovations and new product developments in this domain as we continue to witness intense reformation and diversification of food palates globally. In addition, integrating these platforms with trained artificial intelligence can further uplift them to smart sensing platforms that can, to an extent, also predict emerging food safety threats in terms of adulterants and/or pathogens. To make this a real scenario, coordinated efforts and synchronized response will be required from several stakeholders working in this evolving domain.
随着我们继续见证全球食品口味的激烈改革和多样化，这将为该领域的创新和新产品开发提供特别丰富的资源。此外，将这些平台与训练有素的人工智能相结合，可以进一步将其提升为智能传感平台，在某种程度上，还可以预测掺假和/或病原体方面出现的食品安全威胁。为了使这成为一个真实的场景，将需要在这个不断发展的领域中工作的几个利益相关者协调努力和同步响应。
5. 结论
To conclude, utilizing metabolomics for evaluating flavor-associated metabolites in PBPs would likely become a necessity in coming years and it will see multiple applications from product authenticity, quality assessment, new product development and enhanced food safety.
利用代谢组学来评估植物基产品（PBPs）中与风味相关的代谢物，在未来几年内很可能会成为一种必然需求，并且将在产品真实性验证、质量评估、新产品开发和增强的食品安全等多个方面展现出广泛的应用。
原文链接：
Pavagadhi S, Swarup S. Metabolomics for Evaluating Flavor-Associated Metabolites in Plant-Based Products. Metabolites. 2020; 10(5):197. https://doi.org/10.3390/metabo10050197
