HEALTH BENEFITS OF APPLE PHENOLICS FROM POSTHARVEST STAGES FOR POTENTIAL TYPE 2 DIABETES MANAGEMENT USING IN VITRO MODELS

An increasing number of studies indicate that regular intake of fruits and vegetables have clear links to reduced risk of chronic diseases like diabetes and cardiovascular disease. The beneficial effects in many cases have been attributed to the phenolic and antioxidant content of the fruits and vegetables. Apples are a major source of fiber and contain good dietary phenolics with antioxidant function. Previous epidemiological studies have indicated that intake of apples reduces the risk of developing type 2 diabetes. Our studies indicate that this reduced risk is potentially because of the modulation of postprandial glucose increase by phenolics present in apples via inhibition of α -glucosidase. Phenolic content was evaluated during 3 months of postharvest storage of four varieties of apples and results indicated positive linkage to enhanced postharvest preservation and α -glucosidase inhibition. These in vitro results along with existing epidemiological studies provide strong biochemical rationale for further animal or human clinical studies.

PRACTICAL APPLICATIONS

The understanding of phenolic-linked antioxidant enzyme responses during postharvest storage of apples has implications for using the same phenolic functional ingredients toward health benefits such as α-glucosidase inhibition linked to glycemic index control associated with type 2 diabetes. Therefore strategies to understand phenolic-linked postharvest preservation and natural treatments to extend this preservation in selected varieties, such as McIntosh and Cortland in this study, can be basis for food ingredient design for health benefits. These strategies can then be extended to prolong postharvest preservation and enhance phenolic linked human health benefits of a wide variety of fruits and vegetables.     

超声协同钙浸渍对樱桃番茄贮藏过程中酚类物质的影响研究

研究超声协同钙浸渍处理对樱桃番茄贮藏过程中酚类物质的含量、结构和抗氧化能力以及相关酶活性的影响。结果表明:超声协同钙浸渍处理有效抑制贮藏期间樱桃番茄果实中多酚氧化酶(polyphenol oxidase,PPO)、过氧化物酶(peroxidase,POD)活性和苯丙氨酸转氨酶(phenylalanine ammonia-lyase,PAL)活性,维持总酚含量,延缓后熟。质谱结果表明,超声协同钙浸渍技术有效抑制贮藏期间樱桃番茄果实主要酚酸的消耗,更好的维持酚类物质的结构特性和抗氧化活性。综上所述,超声协同钙浸渍技术能够有效维持樱桃番茄贮藏期间品质特性,增加果实耐贮藏性。     

茉莉酸甲酯诱导采后番茄果实抗病的作用

为寻找安全无毒的采后保鲜防病途径,探讨茉莉酸甲酯(MeJA)在采后番茄果实诱导抗病性中的作用和机制。以绿熟期“丽春”番茄为材料,接种灰霉菌,并观察该菌对诱导抗病性的作用,研究MeJA对采后抗病的反应及其诱导作用,并对不同处理中番茄果实抵抗病原菌侵染能力、茉莉酸类物质含量、植物抗菌物质含量的诱导差异进行检测。结果表明：外源MeJA处理能够有效抑制番茄果实采后病害的发生,提高果实对琏格孢霉(Alternaria solani)、灰葡萄孢霉(Botrytis cinerea)、扩展青霉(Penicillium expansum)、匍枝根霉(Rhizopus stolonifer)病原菌侵染的广谱抗性,并通过诱导包括病程相关蛋白、酚类、番茄红素在内的抗菌物质积累,达到诱导抗病效果。     

硫化氢在采后果蔬贮藏保鲜中的应用

硫化氢作为植物体内的一种气体信号分子,可以调节植物的代谢,影响采后果蔬贮藏期间的生理活动及营养品质。硫化氢能够参与调控果蔬的成熟衰老,激发防御基因的表达,诱导植物的病伤害反应、抗性的形成,延缓其采后衰老,延长货架寿命。本文综述了国内外关于硫化氢在采后果蔬贮藏保鲜中的研究进展,从采后生理学角度出发,对硫化氢在果蔬的代谢过程中的作用进行阐述,主要对感官品质、能量代谢、呼吸强度、乙烯生成、褐变和病害6个方面进行探讨,以期为今后硫化氢在果蔬保鲜上的研究及应用提供参考依据。     

茉莉酸甲酯处理对采后葡萄果实酚酸合成和抗氧化活性的影响及其机理研究

以‘巨峰’葡萄果实(Vitis vinifera L.× V. labrusca L. cv. ‘Kyoho’)为试材,研究了10μmol/L茉莉酸甲酯(methyljasmonate,MeJA)熏蒸处理对采后葡萄果实在1℃贮藏期间酚酸含量和抗氧化活性的影响,并从苯丙烷类代谢角度分析了相关机理。结果显示：10μmol/L MeJA处理可显著抑制葡萄果实贮藏期间腐烂率和落粒率的上升,诱导苯丙烷类代谢关键酶苯丙氨酸解氨酶(PAL)、肉桂酸羟化酶(C4H)和查耳酮合成酶(CHS)活性的上升并延缓对香豆酰-CoA连接酶(4-CL)活性的下降,同时显著提高果实主要酚酸(没食子酸、咖啡酸、原儿茶酸、丁香酸和p-香豆酸)和总酚含量并维持了DPPH自由基清除率和总还原力。结果表明：MeJA可通过调控葡萄果实苯丙烷类代谢相关酶系的活性,从而有效诱导果实中酚酸的合成并维持果实贮藏期间抗氧化活性,最终提高了果实采后食用和营养品质。     

低温维持果蔬采后活性氧代谢平衡的抗氧化转录调控机制研究进展

果蔬采后活性氧（reactive oxygen species,ROS）代谢失衡造成氧化胁迫,加速品质劣变,破坏其商业价值。文章以ROS代谢与果蔬贮藏品质的关系为切入点,探讨低温诱导抗氧化酶活性延缓果蔬采后品质劣变的作用;同时,从转录调控角度综述bHLH、WRKY及NAC等低温响应转录因子参与果蔬采后抗氧化作用,进而揭示低温延缓果蔬品质劣变的抗氧化转录调控作用的可能机制,旨在为开展果蔬采后品质生理生化及分子生物学等基础研究及进一步阐明果蔬采后成熟衰老和品质劣变机制提供新的理论依据。     

温州蜜柑、椪柑采后酚类物质及抗氧化活性比较研究

通过研究温州蜜蜂柑、椪柑两个常见柑橘品种贮藏期间类黄酮、酚酸类物质及抗氧化活性的变化规律,评价其采后的营养品质。结果表明：贮藏60d后温州蜜柑较好地保持了抗坏血酸含量,而椪柑损失较大。类黄酮类物质较稳定,温州蜜柑中黄烷酮含量贮藏后有所增加,椪柑中则呈缓慢下降趋势,2种柑橘中酚酸类物质贮藏后都有所增加。总酚含量在贮藏前期呈下降趋势,贮藏后期温州蜜柑中总酚含量增加而在椪柑中进一步下降。抗氧化能力与抗坏血酸的变化趋势类似。与椪柑相比,贮藏期间温州蜜柑能更好地保持果实的营养品质及酚类物质,从而保持较高的抗氧化活性。     

Nutritional comparison of fresh,frozen, and canned fruits and vegetables II. Vitamin A and carotenoids,vitamin E,minerals and fiber

In this second part of our review, we examine the literature for changes in carotenoids, vitamin E, minerals, and fiber due to processing, storage, and cooking of fresh, frozen, and canned fruits and vegetables. While inconsistencies in methodology and reporting methods complicate interpretation of the data, the results show that these nutrients are generally similar in comparable fresh and processed products. The higher levels of carotenoids typically found in canned as compared to fresh products may be attributed to either reporting results on a wet rather than dry weight basis, greater extractability, or differences in cultivars. There are relatively few studies on processing, storage, and cooking effects on vitamin E in fruits and vegetables. Further research is needed to understand nutritional changes in those few fruits and vegetables rich in vitamin E, such as tomatoes. Minerals and fiber are generally stable to processing, storage, and cooking, but may be lost in peeling and other removal steps during processing. Mineral uptake (e.g., calcium) or addition (e.g., sodium) during processing can change the natural mineral composition of a product. Sodium concerns in canned food can be addressed by choosing products with no salt added. Since nutrient content varies considerably by commodity, cultivar, and postharvest treatments, inclusion of a wide variety of fruits and vegetables in the diet is encouraged. Copyright © 2007 Society of Chemical Industry     

Effects of high hydrostatic pressure processing and subsequent storage on phenolic contents and antioxidant activity in fruit and vegetable products

Fresh fruits and vegetables have been reported to possess a variety of bioactivities partly due to their high abundance of phenolics. However, traditional thermal pasteurisation during fruit and vegetable processing typically induces a pronounced loss of phenolic compounds. In contrast, nonthermal pasteurisation techniques, especially high hydrostatic pressure (HHP) processing, are beneficial to the retention of phenolics. In addition to more effectively keeping original freshness, flavour and colour of fruit and vegetable products to the greatest extent, in most cases, HHP processing and subsequent storage more effectively sustain the levels of phenolic compounds and antioxidant activity in fruit and vegetable products compared with thermal pasteurisation. Therefore, HHP processing has a huge potential to preserve fruit and vegetable products rich in phenolic compounds.     

超声声学效应在果蔬酚类化合物提取中的研究进展

本文综述了应用超声声学效应提取果蔬酚类化合物的增强优势,并分析了超声声学效应可能引起酚类化合物的降解反应以及对其稳定性的影响。同时,本文介绍了目前超声辅助提取果蔬酚类化合物的商业化应用现状,为加快超声辅助技术在提取果蔬酚类化合物中的有效利用,促进该技术在食品工业领域的快速发展提供参考。     

Postharvest Heat Treatment for Mitigation of Chilling Injury in Fruits and Vegetables

Low-temperature storage is widely used as a postharvest treatment applied for delaying senescence in vegetables and ornamentals and ripening in fruits, upholding their postharvest quality. But the refrigerated storage of tropical and subtropical crop plant species provokes a set of physiological alterations known as chilling injury (CI) that negatively affect their quality and frequently renders the product not saleable. The increasing demand for consumption of fresh fruits and vegetables, along with restriction on the use of synthetic chemicals to reduce CI, has encouraged scientific research on the use of heat treatments as an environment-friendly technology for CI mitigation. Membrane damage and reactive oxygen species production are multifarious adverse effects of chilling as oxidative stress in sensitive fruits and vegetables. Chilling mitigation in heat-treated fruits and vegetables could be attributed to (1) enhancement of membrane integrity by the increase of unsaturated fatty acids/saturated fatty acids (unSFA/SFA) ratio; (2) enhancement of heat shock protein gene expression and accumulation; (3) enhancement of the antioxidant system activity; (4) enhancement of the arginine pathways which lead to the accumulation of signaling molecules with pivotal roles in improving chilling tolerance such as polyamines, nitric oxide, and proline; (5) alteration in phenylalanine ammonia-lyase and polyphenol oxidase enzyme activities; and (6) enhancement of sugar metabolism. In the present review, we have focused on the impacts of heat treatments on postharvest chilling tolerance and the mechanisms activated by this environment-friendly technology in fruits and vegetables.     

Effects of Ultrasound on Spoilage Microorganisms,Quality, and Antioxidant Capacity of Postharvest Cherry Tomatoes

Mature‐green cherry tomato fruits (Lycopersicon esculentum cv. Jinyu) were exposed to different power densities of ultrasound (66.64, 106.19, and 145.74 W/L) at 25 °C to study ultrasound non‐thermal effects on the storage properties. Among the three levels of ultrasound irradiation, 106.19 W/L ultrasound was effective in reducing the spoilage microorganisms, delaying postharvest ripening through inhibiting ethylene production and respiration rates, and consequently maintaining fruit firmness, flavor, enzyme activities, antioxidants (total phenolics, total flavonoids), and the total antioxidant capacity of cherry tomatoes. The 66.64 W/L ultrasound had similar effects but to a lesser extent. Meanwhile, although 145.74 W/L ultrasound resulted in higher content of ascorbic acid (AA), it showed many negative effects on the storage quality of fruits. These results demonstrated that ultrasound of appropriate power density had great potentials in inhibiting decay, maintaining flavor and nutritional quality of cherry tomatoes.     

Improving the nutraceutical value of mango during ripening by postharvest irradiation with blue LEDs via enhancing of antioxidant enzyme activities

Light-emitting diodes (LEDs) are emerging as a clean technology for improving the postharvest preservation of fruits. Mangoes were irradiated with blue LEDs (75 µmol s^-1 m⁻²) and then stored for 15 days. The fruit quality, including the content of antioxidant compounds and activities of antioxidant enzymes, was evaluated during storage. The treatment with blue LEDs delayed the changes associated with the senescence processes, including the changes in softening, weight loss, total soluble solids content, and titratable acidity. Treatment also caused increases in the antioxidant capacity (1.33-fold), ascorbic acid (1.69-fold), total phenolic (1.33-fold), flavonoids (1.50-fold), and carotenoids content (1.18-fold) compared to control. At the end of storage, blue LEDs treatment maintained higher phenylalanine ammonia-lyase (1.28-fold), peroxidase (1.58-fold), catalase (2.21-fold), and ascorbate peroxidase (1.51-fold) activities. Our findings indicate that blue LEDs might be a potential elicitor that modulates oxidative homeostasis and improves the antioxidant and nutritional status of mango by enhancing the activity of antioxidant enzymes.     

采后处理对果蔬细胞壁组成的影响

果蔬采后的贮藏寿命及食用品质与其细胞壁组成的变化密切相关。以延长果蔬采后的储藏寿命和最大限度保留其营养成分为目的的采后处理技术不断涌现．但有关这些技术背后的机理一直缺乏系统研究。为推动我国果蔬储藏技术的深入研究,本文在大量查阅和总结文献的基础上,对采后钙、1-甲基环丙烯、热处理及高压处理对果蔬细胞壁的影响进行综述．并就这方面今后的重点研究方向提出了建议。     

Impact of processing and storage on the phenolic profiles and contents of pomegranate (Punica granatum L.) juices

Juices were obtained on pilot-plant scale from untreated, steamed and peeled pomegranate fruits (Punica granatum L.), respectively, by applying increasing pressures and various juice treatments, i.e., enzymatic treatment, filtration, clarification and pasteurization, to determine the influence of process technology on the phenolic profiles and contents of the juices. Polyphenols were characterized and quantified by HPLC-DAD-ESI/MSⁿ, and total phenolics and antioxidant capacity of the juices were determined by Folin–Ciocalteu, FRAP and TEAC assays, respectively. The total amounts of anthocyanins and colorless phenolics in the juices significantly differed depending on the applied technology. Highest phenolic recoveries were obtained from steamed fruits without further treatment. In contrast, lowest phenolic contents were determined in the juices produced from peeled fruits, i.e., the isolated seeds with adherent arils. With increasing pressures, polyphenol recoveries were enhanced, whereas juice treatments such as microfiltration and fining lowered phenolic contents of the juices. Furthermore, the amounts of individual phenolics were determined by HPLC-DAD with ellagitannins dominating the phenolic profiles. Juices solely produced from the edible parts of pomegranate exhibited lower amounts of ellagitannins compared with the juices from entire fruits. In contrast, the former juices were characterized by the highest amounts of gallotannins, hydroxybenzoic acids, hydroxycinnamic acids and dihydroflavonols. These results were consistent with the astringency of the juices. Additionally, storage experiments were performed at 4 °C and 20 °C in the dark and 20 °C under light exposure, revealing significant pigment degradation and concomitant color loss, especially at elevated temperatures and upon illumination, whereas the contents of non-anthocyanin phenolics and antioxidant capacity remained virtually unchanged throughout storage.     

POLYPHENOLOXIDASE ACTIVITY, BROWNING POTENTIAL AND PHENOLIC CONTENT OF PEACHES DURING POSTHARVEST RIPENING

Changes in the polyphenoloxidase (PPO) activity and the phenolic content of peaches (Prunus persica cv. Premier) during postharvest ripening were studied. The fruits were stored at 12 or 25C for up to 15 days. The quantity of extractable proteins was maximum at 6–10 days storage at 25 and 12C, coinciding with the onset of the yellowness in the fruits. The PPO activity increased up to the ripening stage, showing a maximum value at 8 days of storage. This was coincident with the maximum degree of browning as evaluated by the absorbance at 440 nm. The amount of total phenolics and chlorogenic acid in the fruits decreased during storage; however, the differences were not significant. The browning potential closely correlated with the enzyme activity, but not with the phenolic content.     

果蔬采后色素物质代谢调控研究进展

色泽是果蔬采后主要的感官品质之一,它是消费者判断果蔬成熟度、新鲜度、商品可接受度及营养价值的重要参数。决定果蔬采后色泽的主要色素有叶绿素、类胡萝卜素和花色苷,它们的代谢使果蔬呈现红、橙、黄、绿、蓝、紫等多种颜色。果蔬采后常发生的褪绿、褐变、黄化和白化等转色现象,也与果蔬色素代谢过程密切相关。研究果蔬采后色素代谢及其调控具有重要意义。本文综述了物理因子、化学因子和生物技术等在调控果蔬采后色素代谢方面的作用和机理,旨在为采后果蔬色泽的有效调控提供一定的理论参考。     

AP2/ERF转录因子调控果蔬采后病害的作用研究进展

果蔬在采后贮藏运输过程中易受到各种生理性病害和侵染性病害的胁迫,这些病害极大地缩短了各类水果和蔬菜的货架期。已有研究表明,AP2/ERF转录因子超家族在果蔬响应各种采后病害中起着重要作用,该家族转录因子可参与调控果蔬的生长发育,并对各类生物和非生物胁迫作出响应。为了明确AP2/ERF转录因子对果蔬采后生理性病害和侵染性病害的调控作用,本文对AP2/ERF转录因子及其在果蔬中的分布和数量进行了概述,并阐明了其响应果蔬采后生理性病害和侵染性病害的作用及机理,介绍AP2/ERF转录因子在香蕉、黄瓜、辣椒等果蔬中响应采后病害的研究进展,以期为研究其他果蔬中的AP2/ERF转录因子以及利用AP2/ERF转录因子增强采后果蔬对病害的抗性提供参考。     

茉莉酸甲酯调控果蔬采后品质的机制及应用研究进展

茉莉酸甲酯（methyl jasmonate,MeJA）是一种广泛存在于植物中的生长调节因子,具有广谱的生理效应,其作用于果蔬能够显著诱导果蔬产生抗病性、提高果蔬的耐冷能力、改善果蔬采后的感官品质和耐贮性。MeJA改善果蔬采后品质的机制主要包括诱导基因的表达、提高抗氧化及抗病相关酶的活性、促进抗性物质的积累、改善果蔬体内能量的代谢等方面。本文就MeJA的结构及理化性质、在果蔬采后方面的应用现状、作用机制及其在果蔬生产中的作用方式进行了综述,并讨论了其研究和应用前景,以期为MeJA在果蔬采后中的深入研究及推广应用提供参考。     

组学技术与果蔬采后质量和安全控制

果蔬可以提供营养, 有利于人类健康, 而果蔬的后熟及其与环境的相互作用会影响果蔬采后的质量和安全。对果蔬生物学过程的了解和掌握是减少果蔬采后损失和保障果蔬采后质量和安全的关键。在过去的10多年, 基于组学技术的系统生物学在了解果蔬后熟及其与环境相互作用的分子机制方面得到了越来越多的应用。本文对此做了细致的总结, 指出了存在的不足, 并提出了未来的发展方向。