基于叶绿素的果蔬护绿方法研究进展

叶绿素是存在于绿色植物中的一种独特而重要的营养物质,在果蔬贮藏与加工过程中,如何保护叶绿素是一大难题.本文对叶绿素的性质、叶绿素稳定性的影响因素及果蔬护绿技术等进行了综述.     

Characterization of chlorophyll degradation in banana and plantain during ripening at high temperature

Bananas fail to fully degreen when ripening at tropical temperatures, but this abnormal symptom does not occur in plantain. To elucidate the temperature effect on banana degreening, comparison of the colour change and chlorophyll degradation pathway between banana and plantain during ripening at 20 or 30 °C was carried out. Compared to bananas ripening at 20 °C and plantains at 20 °C or 30 °C, bananas at 30 °C contained significantly higher levels of chlorophylls, chlorophyllide a and pheophorbide a at the end of the ripening process, linearly correlating to the colour scores of a^∗, b^∗ and Hue angle. Whilst higher chlorophyllase activity was recorded in both banana and plantain at 30 °C as to the fruits at 20 °C, 30 °C inhibited Mg-dechelatase activity in banana, but not in plantain. The reduction of Mg-dechelatase activity in banana peel at 30 °C may contribute to repressed chlorophyll degradation and lead to uneven degreening.     

Analysis of carotenoids with emphasis on 9-cis β-carotene in vegetables and fruits commonly consumed in Israel

Recent epidemiological studies have directed the attention from the synthetic all-trans β-carotene to natural carotenoids predominant in fruits and vegetables as possible active ingredients for prevention of cancer and cardiovascular diseases. Seventeen fruits and 17 vegetables commonly consumed in Israel and the β-car-otene-rich alga, Dunaliella bardawil, were analysed for their content of carotenoids with emphasis on 9-cis β-carotene by reversed-phase, 3D photodiode array HPLC. Fourteen carotenoids were eluted in order of decreasing polarity, from polar oxycarotenoids to lipophilic hydrocarbons, and quantified in μg carotenoid per gram freeze-dried plant sample. The richest sources of total carotenoids (>100μg/g dry weight) in Israeli fruits were pittango, mango and papaya while, in vegetables, the predominant types were carrot, dill, parsley, tomato, lettuce, sweet potato and red pepper. Red fruits and vegetables contained mainly lycopene. Yellow and orange fruits and vegetables had high contents of hydrocarbon carotenes with substantial levels of cryptoxanthins and xanthophylls. The green vegetables had high contents of both xanthophylls and hydrocarbon carotenes. Relatively high ratios (9-cis to all-trans β-carotene) of above 0.2 g/g were noted in sweet potato, papaya, parsley, lettuce, dill, apricot, pepper, prune and pumpkin, compared to the high ratio of 9-cis to all-trans β-carotene in the alga Dunaliella (~ 1.0 g/g). The high content of 9-cis β-carotene in certain fruits and vegetables and the wide variety of carotenoids and stereoisomers of carotenoids in all plants should shift nutritional and medical attention from the synthetic all-trans β-carotene toward natural carotenoids as potential candidates for chemoprevention.     

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。     

Digestion property and synergistic effect on biological activity of purple rice (Oryza sativa L.) anthocyanins subjected to a simulated gastrointestinal digestion in vitro

Anthocyanins, a group of polyphenolic pigments, have been proved to possess various bioactivities. However, they are unstable in the small intestine and absorbed with low bioavailability. The discrepancy between the low bioavailability of anthocyanins and their good bioactivities has not been illuminated yet. Moreover, information about the digested property and stability of purple rice anthocyanins in the alimentary tract is still limited. Thus, the present work was designed to study the digestion property and the changes in antioxidant and cytoprotective activities of purple rice anthocyanins using an in vitro digestion model, and to investigate the interactions between gastric and intestinal digested anthocyanins. The results showed that anthocyanins amount and antioxidant and cytoprotective effects didn't change significantly during gastric digestion. However, about 76% of total anthocyanins were degraded during intestinal digestion. The IC₅₀ values of intestinal digested sample tested by DPPH and ABTS methods were about 19.1 and 16.9 μg/mL, respectively, far higher than that of non-digested sample (about 7.7 and 7.1 μg/mL, respectively). Cytoprotective effect of intestinal digested sample also decreased significantly. Synergistic effects on antioxidant and cytoprotective activities were observed between the gastric and intestinal digested samples at a relative low concentration. Those results suggest that the bioactivities of purple rice anthocyanins may be changed after digestion and enhanced through the synergies between their gastric and intestinal digested catabolites.     

淀粉-多酚复合物制备及其消化特性研究进展

多酚是一种从植物中提取的,具有降血糖、抗炎、抗氧化、抗癌和抗菌特性的化合物。在一定条件下,淀粉可以与多酚发生相互作用,形成两种类型的复合物。一种是非包合物,即酚类化合物的羟基和羰基与淀粉相互作用形成分子间聚集体；另一种是V型包合物,即酚类化合物部分包封在淀粉的内部疏水螺旋内。上述两种复合物均对降低淀粉消化率有积极作用,但受加工方式、淀粉和多酚种类的影响。因此,本文在总结上述因素对淀粉-多酚复合物理化及消化特性影响的基础上,指出目前淀粉-多酚复合物研究中存在的不足之处,提出进一步的研究重点,以期为淀粉-多酚复合物在不同食品中的应用提供参考。     

鞣花酸和尿石素类代谢产物的生物活性及其对肠道健康的作用研究进展

鞣花酸（ellagicacid,EA）作为一种天然抗氧化剂,是一种广泛存在于众多蔬菜、水果及坚果中的多酚类化合物,可经过肠道微生物的代谢生成尿石素类物质。但EA在肠道中的利用度较低;而其代谢产物尿石素类较易被肠道吸收,故被认为是发挥EA抗氧化作用的物质基础。动物模型及临床试验研究表明,EA及其代谢产物尿石素可有效改善肠道微生物菌群、促进肠道健康、预防或抑制肠道疾病的发生发展。EA及尿石素的营养生理作用主要包括抗氧化、抗炎及微生物菌群调控等作用。本文综述了EA及尿石素的结构、代谢途径、生物活性及其在肠道疾病研究中的应用。     

Phenolic compounds and plant extracts as potential natural anti-obesity substances

One strategy to prevent obesity could consist in the inhibition of the pancreatic lipase (PL). In an attempt to find natural antiobesity agents, phenolic compounds (PCs) and plant extracts were investigated on PL activity. Epigallocatechin-3-gallate > kaempferol and quercetin were detected as potent PL inhibitors, with ICs₅₀ of 0.8, 13.4 and 21.5 μM, respectively. Plant extracts from green tea and grape seed also shown potent inhibitory effect. Selected PCs were then assayed in an in vitro model of simulated intestinal fat digestion, based on the lipolysis of triolein. In such conditions closer to physiological reality, resveratrol, but also epigallocatechin-3-gallate and quercetin reduced the triolein digestion to ±50%. This could delay or decrease in vivo fatty acid absorption by enterocytes. This work therefore suggests that some PCs, at concentrations easily reached in the intestine following ingestion of tea beverages, fruits or vegetables, but also flavonoid-enriched supplements or functional food, are potential candidates for obesity prevention.     

正交试验优化魔芋葡甘聚糖复合膜配方及其对青椒的保鲜作用

以魔芋葡甘聚糖为膜基质,利用5因素2水平正交试验筛选对青椒具有良好保鲜作用的涂膜保鲜剂组合,分析其对青椒的衰老指数、丙二醛(MDA)含量、VC含量和叶绿素含量的影响。结果表明：青椒的最佳复合涂膜剂组合为8.0g/L魔芋精粉+1.0g/L曲酸+0.4g/L EDTA+0.1g/L抗坏血酸+0.35%甘油。该涂膜组合处理青椒,贮藏30d后,衰老指数为0.32,MDA、VC含量和叶绿素含量分别为0.87nmol/g、25.0mg/100g和0.08mg/g,保鲜效果明显优于对照。     

Chlorophyll-bound Magnesium in Commonly Consumed Vegetables and Fruits: Relevance to Magnesium Nutrition

ABSTRACT: Magnesium is bound as the central atom of the porphyrin ring of the green plant pigments chlorophyll a and b . It has been suggested that chlorophyll-bound magnesium may play an important role in magnesium nutrition because when iron is similarly bound in the porphyrin ring of heme, it is absorbed to a greater extent than non-heme iron. We have analyzed 22 frequently consumed fruits and vegetables for the chlorophyll content by high-pressure liquid chromatography and for magnesium with atomic absorption spectroscopy. Chlorophyll concentrations ranged from 6 μg/g (grape) to 790 μg/g (spinach) (median 63 μg/g). Magnesium concentrations ranged from 48 μg/g (grape) to 849 μg/g (spinach) (median 122 μg/g). In the green leafy vegetables, such as spinach and lettuce, chlorophyll-bound magnesium represented 2.5% to 10.5% of total magnesium whereas other common green vegetables, pulses and fruits contained < 1% chlorophyll-bound magnesium. The chlorophyll content of spinach was further decreased by about 35% on thawing frozen spinach or on chopping fresh spinach, and this degradation increased to about 50% after boiling and steaming. Based on the present results and published food consumption data, we estimate that chlorophyll-bound magnesium represents a very low fraction of total magnesium intake in industrialized countries, less than 1% in the case for data obtained from Switzerland. Thus, chlorophyll-bound magnesium is of little relevance to magnesium nutrition.     

In vitro bioaccessibility of carotenoids and tocopherols from fruits and vegetables

Aim of the study

To assess the in vitro bioaccessibility of carotenoids, including xanthophyll esters, and tocopherols from fruits and vegetables.

Results

Stability for carotenoids and tocopherols was over 70%. Xanthophyll esters were cleaved by cholesterol esterase but not by human pancreatic lipase. Less than 40% of the β-cryptoxanthin initially present was hydrolyzed and the amount of free xanthophylls recovered was higher when liquid was used than when fresh homogenized matrix was employed. cis-Isomers of β-carotene and lutein did not significantly increase during the process. Xanthophylls were more efficiently transferred into supernatants than tocopherols and β-carotene. cis-Carotenoids, epoxy-xanthophylls and ester forms were also transferred.

Conclusion

The results are consistent with observations in other in vitro digestion models and human studies and support the usefulness of in vitro assessment to study food-related determinants of the bioavailability of carotenoids and tocopherols from fruits and vegetables.     

植物多酚降血糖机制的研究进展

多酚类化合物是植物的次生代谢产物,广泛存在于自然界中,包括黄酮类化合物、单宁、绿原酸等。研究表明,经常摄入富含多酚类化合物的蔬菜、水果和饮料可以减缓心脑血管疾病、糖尿病、肥胖等慢性代谢疾病甚至癌症的发生和发展。本文从植物多酚可以通过促进胰岛素合成与分泌、抑制葡萄糖转运、调节肠道菌群等方面对血糖起调节作用进行论述,以期为植物多酚降血糖功能提供理论依据。     

Major Australian tropical fruits biodiversity: bioactive compounds and their bioactivities

The plant kingdom harbours many diverse bioactive molecules of pharmacological relevance. Temperate fruits and vegetables have been highly studied in this regard, but there have been fewer studies of fruits and vegetables from the tropics. As global consumers demand and are prepared to pay for new appealing and exotic foods, tropical fruits are now being more intensively investigated. Polyphenols and major classes of compounds like flavonoids or carotenoids are ubiquitously present in these fruits, as they are in the temperate ones, but particular classes of compounds are unique to tropical fruits and other plant parts. Bioactivity studies of compounds specific to tropical fruit plants may lead to new drug discoveries, while the synergistic action of the wide range of diverse compounds contained in plant extracts underlies nutritional and health properties of tropical fruits and vegetables. The evidence for in vitro and animal bioactivities is a strong indicator of the pharmacological promise shown in tropical fruit plant biodiversity. In this review, we will discuss both the occurrence of potential bioactive compounds isolated and identified from a selection of tropical fruit plants of importance in Australia, as well as recent studies of bioactivity associated with such fruits and other fruit plant parts.     

Beneficial effects of Trichoderma genus microbes on qualitative parameters of Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort.

The consumption of vegetables and fruits has always been seen as health promoting. One group of vegetables that were already used for medicinal purposes in ancient times and are now seen as possibly cancer protective are vegetables of the Brassica genus. The protective effect of brassicas against cancer may be due to their relatively high content of glucosinolates. Certain hydrolysis products of glucosinolates have shown anticarcinogenic properties. However, not properly cooking procedures and storage could drastically reduce the content of glucosinolates in Brassicaceae plants. This study aims to assess whether the use of agronomic techniques can increase the content of glucosinolates in Brassica plants, in order to offset these losses. For this purpose were used strains of beneficial microorganisms of Trichoderma harzianum TM10, T. atroviride P1, already known biocontrol agents, and their metabolites harzianum acid and 6-pentyl-α-pyrone on plants of Brassica rapa subsp. sylvestris var. esculenta ecotype “Sessantino” (called with the trivial name “friarielli” in the south of Italy where this variety is very popular and consumed). Moreover, the antioxidant activity and ascorbic acid content were determined on plant extracts, followed by liquid chromatography–mass spectrometry analysis of glucosinolates. In order to obtain the extraction of constituents from plant material, microwave-assisted extraction was used. Results obtained showed that the use of Trichoderma and its metabolites determined an increase in glucosinolates in plants of B. rapa. Accordingly, the proposed method could be used on other plants of food interest to increase their nutritional properties.     

Ageing and irradiance enhance vitamin E content in green edible tissues from crop plants

BACKGROUND: Tocopherol (vitamin E) is an antioxidant essential in human nutrition. Several approaches have aimed to enhance tocopherol content in crops by the genetic modification of plants, a practice that generates some social concern. As tocopherol accumulates with leaf age in some wild plants and the antioxidant mechanisms respond with flexibility to stress conditions, it is hypothesised that tocopherol content can be increased in edible plants by the manipulation of harvesting time and growth conditions, in particular irradiance. RESULTS: Ontogenic changes in tocopherol concentration have been studied in photosynthetic tissues of edible leaves (lettuce, spinach, corn salad and dandelion) and green fruits (cucumber and pepper). In all species, tocopherol content increased with tissue age. Spinach showed the fastest rate of tocopherol accumulation, and growth at higher irradiance had a synergistic effect on the rate of accumulation. The same irradiance dependence of this accumulation was observed in fruits, but a final decrease with senescence occurred in cucumber. CONCLUSION: This study demonstrates that the content of tocopherol in vegetables can be notably enhanced (or reduced) by simply selecting the appropriate harvesting time and/or by manipulating the environmental conditions during the growth period. Copyright © 2010 Society of Chemical Industry     

褪黑素调控果蔬采后保鲜研究进展

褪黑素是一种广泛存在于生物体中的吲哚胺类化合物,已经被证实广泛分布在高等植物的组织和器官中,具有调节植物种子萌发、生长发育、抗逆性以及成熟衰老等重要作用。最新研究表明褪黑素在延缓果蔬采后衰老和品质劣变中具有显著的调控作用。本文首先简述植物中褪黑素合成途径、部分果蔬中褪黑素的含量及其影响因素,重点综述褪黑素对果蔬采后生理（呼吸作用、乙烯生成、抗氧化酶活力）和品质（色泽、生物活性物质、抗氧化活性）的调控作用,并对其可能的调控机制进行详细解析,最后归纳褪黑素在果蔬采后保鲜研究中存在的问题和将来的研究重点,为今后褪黑素在果蔬采后保鲜中的研究和应用提供参考。     

Promoting food security and enhancing Nigeria's small farmers' income through value-added processing of lesser-known and under-utilized indigenous fruits and vegetables

In Nigeria and other African countries, there are hundreds of lesser-known indigenous crops as well as other food plants gathered from the wild that contribute to food security and play vital roles in the nutrition of the people particularly the rural populace. These native crops and wild food plants that have received little research attention or extension activities and have been largely neglected by the mainstream of international science include a wide variety of wild indigenous fruits and vegetables that enrich the diet of the rural populace and could thrive with little care and without the use of costly agricultural inputs such as fertilizers, herbicides and pesticides. Among them are numerous fruits of Nigerian trees that grow wild in the rain forest and the woodland savanna zones or are cultivated on small, compound farms. These fruits that are consumed fresh are rich sources of nutrients including ascorbic acid, provitamin A carotenoids, minerals and nutraceuticals with health-promoting benefits. There is the need to promote the cultivation and utilization of many of these indigenous fruit trees including African star apple (Chrysophyllum albidum), African mango (Irvingia gabonensis), African or native pear (Dacryodes edulis) and hog plum (Spondias mombin) that are also of considerable environmental significance and protect them from uncontrolled wood felling activities that result in deforestation. Laboratory studies have shown that good quality fruit leathers, jams, juices and other drinks can be produced from several lesser-known and under-utilized Nigerian fruits and vegetables including African star apple (C. albidum), African mango (I. gabonensis), hog plum (S. mombin), tamarind (Tamarindus indica) and roselle (Hibiscus sabdariffa) using simple procedures suitable for small-scale commercial production including osmotic dehydration, open-kettle jam-making process and mechanical juice extraction followed by hot water pasteurization. Removing the constraints to the development of small-scale food industries which include inadequate electricity supply, use of inappropriate technology, inadequate working capital, high interest rates, and limited access to banks and other financial institutions would facilitate commercial production of these value-added foods in rural communities thereby reducing post-harvest losses, promoting food security, enhancing small farmers' income and contributing to sustainable rural development.     

Effect of natural biostimulants on yield and nutritional quality: an example of sweet yellow pepper (Capsicum annuum L.) plants

BACKGROUND: Modifications in growing techniques can affect the yield and nutritional quality of various cultivated plant species. Owing to its high nutritional value, pepper (Capsicum annuum L.) was used in this study as a model plant to investigate the effect of natural biostimulants on yield and fruit quality parameters under conditions of reduced fertilisation. RESULTS: A positive influence of biostimulant treatment on yield parameters was observed. The overall increase in the pigment content of leaves after biostimulant application agreed well with the higher total and commercial yields of treated pepper cultivars compared with their controls. The results showed that natural biostimulants had a positive effect on the vitamin C and total phenolic contents in pepper fruits during the hot summer season. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS) antioxidant activities were also significantly higher (P < 0.05) in treated plants and correlated strongly with all measured quality parameters except total phenolic content. CONCLUSION: Generally, biostimulants improved the antioxidant activity, vitamin C and phenolic contents in fruits as well as the pigment content in leaves of treated compared with non‐treated pepper plants grown hydroponically. Thus the application of biostimulants could be considered as a good production strategy for obtaining high yields of nutritionally valuable vegetables with lower impact on the environment. Copyright © 2011 Society of Chemical Industry     

清洗技术对鲜切果蔬微生物与品质影响的研究进展

清洗是鲜切果蔬加工过程中必不可少的环节,清洗不仅可以减少微生物数量,还可以去除果蔬经切分后流出的组织汁液,减缓褐变反应,降低营养成分损失,提高食用品质。本文综述了物理清洗、化学清洗和生物清洗技术通过物理或化学作用破坏微生物细胞壁、细胞膜和DNA等而导致其死亡的杀菌机理及其对鲜切果蔬中PPO和POD等褐变相关酶活的抑制作用以及这些技术对鲜切果蔬中V_C、叶绿素和固形物含量等营养物质的维持效果,同时还归纳了适合不同种类鲜切果蔬的清洗技术条件,提出了鲜切果蔬清洗技术的研究方向,以期为今后研究不同清洗技术对鲜切果蔬微生物与品质的影响提供理论依据。     

植物精油对果蔬保鲜作用研究进展

病原微生物引起的腐烂是造成果蔬采后损失的主要原因,由此带来巨大的经济损失。植物精油是植物体内的次生代谢产物,化学组成较为复杂,因其具有抑菌和保持果蔬品质等多方面的作用,引起了食品研究人员的极大兴趣。近年来,植物精油在果蔬保鲜上的应用已成为研究热点。本文就植物精油的抑菌活性、对果蔬防腐保鲜的作用及其机理等方面进行综述及分析,以期为高效、安全的食品天然防腐保鲜剂的开发和植物精油在果蔬保鲜中的应用提供参考。