果蔬气调贮藏的优势及发展前景

介绍了果蔬气调贮藏技术的原理、方法特点及我国气调技术的应用与发展前景。     

梅品种国际登录的五年-写在《中国园林》系统刊登梅国际登录品种彩照专页之前

简单介绍了梅品种国际登录权威申请和批准经过以及近5年的品种登录成果.在此基础上,为了扩大影响和国内外交流,为了梅品名称标准化,以便加速促进梅花与梅果产业化进程,自本期起在<中国园林>陆续刊出梅国际登录品种.相信此举必将对梅业之快速发展,产生一定的推动作用.最后,提出了园艺植物品种国际登录工作展望.     

柿果实的脱涩机理

概述了近20年来柿果实脱涩机理的研究进展,评述了甜柿果实的自然脱涩过程,讨论了乙醇和乙醛处理对涩柿果实的脱涩作用,指出了乙醇是直接与可溶性柿单宁起缩合反应而使柿果实脱涩的化学物质。     

New understandings of how dielectric properties of fruits and vegetables are affected by heat-induced dehydration: A review

Abstract

Dielectric heating (DH) is an alternative to traditional conductive heating. Preservation of fruits and vegetables through drying based on DH is faster than conventional heating systems, needing less processing time, and delivering a better dehydrated product as well as reduced treatment costs. Dielectric properties (DPs) are significant physical qualities that are affected by microwave (MW) and radio frequency (RF) heating systems; these attributes directly affect the electromagnetic arrangement and currents surrounding the materials. In other words, DPs define the response of materials in electric fields at the desired frequency and temperature. Thus, DPs of materials are of increasing interest in the agricultural and food-processing fields. The principles of the DPs of fruits and vegetables according to frequency, temperature, and composition are crucial in the designing and handling of MW and RF heating operations. A consideration of DPs is required to ensure the quality of fruits and vegetables is enhanced throughout the drying process for better quality final products. This review aimed to provide a comprehensive update on the prospects of DH for drying of fruits and vegetables. The factors that affect the DPs during the dehydration process of fruits and vegetables and discussions about the correlation among these factors were also provided. In addition, the fundamentals of DPs and their measurement techniques were also discussed. This study is an update on the state-of-the-art DH system and illustrates the important influence of DPs on the radiative heating of fruits and vegetables.     

Recent Food Drying R&D at Jiangnan University: An Overview

Drying of fresh produce and marine products to develop high-quality dried products cost-effectively has been the theme of extensive research carried out at the School of Food Science & Technology of Jiangnan University, Wuxi, China. Both conventional and innovative hybrid drying techniques encompassing the enhancement of drying rates and quality through utilization of modern ultrasonic and nanotechnology have been examined in detail and reported in the open literature. Some of the work was funded by the industry and eventually utilized in industrial-scale processing. The objective of this article is to summarize the key developments for a wider global readership. An outline of ongoing drying R&D will be provided in the closing section.     

Comparative evaluation of UV-HPLC methods and reducing agents to determine vitamin C in fruits

Vitamin C is one of the most important antioxidant supplied by fruits and vegetables. Therefore a reliable and easy method is needed for its determination. In this work, two UV-HPLC methods for the determination of ascorbic acid were validated and compared in strawberries, tomatoes and apples. In addition, two different reducing agents [dl-1,4-dithiotreitol (DTT) or 2,3-dimercapto-1-propanol (BAL)] were tried for differentiate dehydroascorbic acid and determine vitamin C. Reliability resulted satisfactory for the UV-HPLC methods in each fruit. UV-HPLC methods resulted linear up to 5 mg/100 g and the least detection and quantification limits were <0.18 mg/100 g and <0.61 mg/100 g, respectively. Precision, as relative standard deviation, ranged from 0.6% to 3.9% and the recovery between 93.6% and 104.4%. Although, the UV-HPLC methods resulted useful for the routine analysis of AA and vitamin C in fruits, the best reliability was achieved when using a C18 column and DTT as reducing agent. Moreover, it may be the UV-HPLC method of choice because it is the easiest and cheapest to perform.     

Composition of the essential oil of Daucus gingidium L. ssp. gingidium

The essential oils obtained from leaves and fruits of Daucus gingidium ssp. gingidium have been studied. The main constituents of the essential oil from the leaves were sabinene (26.8%), α-pinene (10.8%), germacrene D (6.9%) and limonene (5.7%). Sabinene (60.6%) was the main compound identified in the essential oil of the fruits, followed by α-pinene (12.2%) and 4-terpineol (5.4%). Furthermore, qualitative and quantitative considerations about differences with literature data on Daucus carota have been made in order to confirm the species status of D. gingidium.     

Effect of a Siraitia grosvenori extract containing mogrosides on the cellular immune system of type 1 diabetes mellitus mice

The purpose of this study was to observe the islet changes of pancreas in insulin-dependent diabetes mellitus (IDDM) mice in comparison to normal mice after application of an extract from Siraitia grosvenori fruits containing mogrosides, in particular, mogroside V. We hypothesized that mogroside extract (MG) attenuates the severity of alloxan-induced IDDM by effects on the immune system. Our data show that IDDM mice exhibited significant injury to pancreatic islets cells, which were atrophic. In addition, alloxan induced a notable increase in the expression of CD8+ lymphocytes to form a dramatic decrease in CD4+/CD8+ ratio (while CD4+ was unchanged). MG, administered to normal and experimental diabetic mice for 4 wk, effectively attenuated the early clinical symptoms, biochemical abnormalities, and pathological damages in pancreatic islets. Furthermore, at low dose, MG regulated the immune imbalance observed in alloxan-induced IDDM mice by up-regulating the CD4+ T-lymphocyte subsets and CD4/CD8 ratio, and altering the intracellular cytokine profiles. The expression of the pro-inflammatory Th1 cytokines: IFN-gamma, TNF-alpha in splenic lymphocytes was altered toward a beneficial Th2 pattern. MG therapy had no effect on normal mice, except that low dosage MG could up-regulate the IL-4 expression levels. The results revealed that MG exhibited antidiabetic effects presumably due to the presence of mogrosides.     

Patulin in homogenized fruit's and tomato products

Patulin is a mycotoxin produced by microscopic fungi belonging to the Penicillium and Aspergillus genera. The natural occurrence of patulin in baby food products marketed in Italy is frequently detectable in moldy fruits and their derivatives. The EC Regulation 1881/06 has limited the presence of patulin in baby food to 10 μg/kg or 10 μg/L on the basis of a Provisional Maximum Tolerable Daily Intake (PMTDI) of 0.4 μg/kg BW set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). A total of 80 homogenized baby foods were analyzed to evaluate the exposure of babies to patulin through the consumption of these products. The experimental tests have revealed significant differences between the products from organic production and those in traditional production in all the categories analyzed. The tomato concentrates showed an average of patulin concentration of 7.15 ng/ml of product; the tomato sauce of 4.05 ng/ml; the tomato sauce to the baby foods of 5.23 ng/ml; the homogenized apple of 0.85 ng/ml; the homogenized pear of 0.79 ng/ml. The tomato sauce conventional vs organic crops showed an average of 5.75 vs 3.49 ng/ml, respectively; the homogenized pear conventional vs organic ones of 0.72 vs 0.76 ng/ml, respectively; the homogenized apple conventional vs organic ones of 1.92 vs 0.13 ng/ml, respectively. The low incidence of the patulin level in Italian products is a clear parameter to establish the quality of the fruits and their derived products.     

Second order derivative spectrophotometric method for determination of vitamin C content in fruits,vegetables and fruit juices

A second-order derivative UV spectrophotometric method for determination of vitamin C [ascorbic acid (AA)] content in a variety of natural samples is described. The method is based on the measurement of a peak–baseline amplitude in the second derivative of the AA spectrum at 267.5 nm. The following corresponding regression equation was obtained within the concentration range 2×10^-5 to 1×10^-4 M AA (3.5–17.6 g/cm³ AA) in 1.0 M HCl solution: ²D_267.5=2.420×10⁴ c+0.025; the correlation coefficient was 0.9993 and the detection limit 4.2×10^-6 M. The results obtained by analysing 21 different species of fruits, vegetables and juices indicated a possibility for a more extensive application of the proposed method. This method is rapid, simple and requires no pretreatment of the analysed material, which makes it suitable for routine analyses. The reliability of the method was confirmed by comparative determinations with the generally accepted 2,6-dichloroindophenol method.