THE STORAGE LIFE OF FRUITS AND VEGETABLES

Exponential curves have been fitted to published temperature/time/quality data for both fresh and frozen fruits and vegetables. The two constants in the exponential equation are used as measures of the relative storage life of the product and of its sensitivity to temperature change. Of these 2 constants, 1 is analogous to the “Q₁₀” value often used to express temperature sensitivity, but it is independent of actual temperature. The two constants are used to provide an index of “storability” of different fruits and vegetables and a tentative classification of produce according to this “storability” is presented. Fitting curves to temperature/time/quality data also allows prediction of the effects on storage life of fluctuating product temperatures, such as are experienced during normal transport and storage.     

THE CHEMISTRY OF TEXTURE IN FRUITS AND VEGETABLES

This review is concerned with the chemistry of the major primary cell wall components, pectins, hemicelluloses and cellulose, under conditions found during the normal handling of fruits and vegetables. These polymeric components are considered separately, then their combined changes during maturation, storage and processing are covered. The effects of tissue conditions, pH, enzymes and salt concentrations on the rate and degree of change are discussed. A large part of the review deals with the important texture-affecting reactions of pectic materials including glycosidic hydrolysis, β-elimination type depolymerization, demethoxylation, and complex formation.     

TEXTURE OF FROZEN FRUITS AND VEGETABLES

This review discusses factors responsible for the texture of fruits and vegetables and the changes brought about by freezing. It describes some of the early work on frozen food texture, as well as the more recent studies of cryogenic and other rapid freezing methods. The effects of storage and cooking on texture are also considered.     

MECHANICS OF FAILURE IN FRUITS AND VEGETABLES

An understanding of mechanical failure in fruits and vegetables is essential to the reduction of damage in processing, handling and transport operations and to the evaluation of textural characteristics of foods. This paper proposes a theory of failure for solid horticultural materials based on the classification of failure as cleavage, slip or bruising. For each of these three modes of failure, the role of intensity of loading or stress in initiating failure is described. It is shown that cleavage is a normal stress phenomenon and that slip and bruising are shear stress phenomena. The mechanical properties of horticultural produce are described in terms of cleavage strength, slip strength and bruising strength; properties which may vary with ripening and loading conditions.
A failure diagram is constructed by superimposing strength boundaries on the normal and shear stress axes of the Mohr's circles representation of the applied stress state. This novel diagram is shown to apply to selected fruits and vegetables. The model can be extended to include buckling. It is shown that horticultural materials do not fail according to one failure criterion alone, but fail, on a rising load, according to the current strength boundary first encountered by an expanding stress state. Potatoes, for example, may fail by cleavage, slip or bruising, depending on the loading conditions.     

果蔬的褐变及其控制方法

果蔬贮藏和加工过程中的褐变是影响其品质的一个重要因素.褐变产生的因素较多,其中酶促褐变是果蔬褐变的最主要原因,也是果蔬贮藏和加工品质保证的主要障碍.概述褐变产生的原因及其控制的方法.     

QUALITY OF MINIMALLY PROCESSED FRUITS AND VEGETABLES

Consumer demand for fresh fruits and vegetables coupled with a demand for convenience is fueling an interest in minimally processed products. Advances in packaging technology provide a potential for improved quality and extended shelf-life of these products, but little is known about the physiological, microbiological and nutritional consequences of minimal processing. Mass marketing and brand-label identification of these products will require a new perspective on shelf-life and quality assurance. A systems approach has been proposed as a framework for quality management of fresh and minimally processed product based on the concept of providing the consumer with optimum quality at purchase and consumption.     

鲜切果蔬加工HACCP体系的应用探讨

根据HACCP原理,对鲜切果蔬加工整个生产过程中出现的质量变化进行分析,确定原料验收、产品杀菌、金属检测等6个关键控制点,制定相应的纠偏措施,并制定出HACCP工作计划表,从而提高产品质量.     

植物提取物用于果蔬防腐保鲜研究进展

致腐菌是诱发果蔬采后病害,造成果蔬在货架期间和贮藏过程腐败变质的主要原因.主要从植物提取物对果蔬采后致腐菌的抑制作用,不同提取方法对致腐菌的抑制效果,提取物用于果蔬防腐保鲜效果三个方面概述了植物提取物在果蔬防腐保鲜上的研究进展.     

果蔬采后商品化处理要点综述

主要阐述了果蔬采后商品化处理的概念、意义和灵活性，并比较详细的介绍了采后商品化处理应着重掌握的主要技术环节。     

NUTRITIONAL CONSEQUENCES OF MINIMAL PROCESSING OF FRUITS AND VEGETABLES

Consumption of fresh or minimally processed fruits and vegetables is increasing due to consumer concern about the effects of processing on nutrients in foods. Relatively little information is available in the literature regarding specific storage and handling techniques that have an impact on nutritional value for fruits and vegetables. Commonly used technologies such as low temperature and controlled atmosphere storage affect vitamin content. The information about other operations such as preparation for the table and irradiation on vitamin losses is fragmentary and may not reflect current practices. It appears that conditions that preserve sensory quality of fruits and vegetables also maintain nutritional value.     

MICROBIOLOGICAL CONSEQUENCES OF MINIMALLY PROCESSED FRUITS AND VEGETABLES

Microbiology is an important factor in the quality of minimally processed fruits and vegetables. Type of food, temperature, humidity, and use of modified atmosphere or low dose irradiation can influence the microecology of a food. Changes in the microbial ecology can likewise influence the ultimate safety and overall quality of fruits and vegetables. Therefore, food scientists must consider the microbiological consequences of all practices involved in production, processing, and delivery of these products.     

豇豆籽蛋白的氨基酸含量与营养价值评价

主要用反相高效液相色谱法分析豇豆籽的氨基酸含量,碱提酸沉法提取豇豆蛋白质,并采用两步法进行体外消化试验,综合评价豇豆籽蛋白的营养价值.结果显示豇豆籽蛋白氨基酸含量为23.28%,氨基酸模式接近参考蛋白模式,蛋氨酸为第1限制性氨基酸,豇豆籽分离蛋白的消化率为96.15%±0.75%,与大豆分离蛋白97.42%±0.88%无显著差异.     

EFFECT OF HIGH PRESSURE PROCESSING ON THE TEXTURE OF SELECTED FRUITS AND VEGETABLES

Prepared fruits and vegetables were subjected to high pressure processing at 100–400 MPa for 5–60 min in an isostatic press and their influence on product texture was evaluated. Pressure had a dual effect on product texture characterized by an initial loss in texture, ascribed to the instantaneous pulse action of pressure, followed by a more gradual change as a result of pressure-hold. The extent of the initial loss and the subsequent partial recovery were pressure dependent with the former more prominent at higher pressures and the latter at lower pressures. The pressure treated samples were generally brighter in color somewhat resembling the appearance of mildly heat treated samples. For all vegetables pressure treated at 100 MPa for 60 min, the initial loss in texture was totally recovered during the pressure hold yielding an overall texture firmer than that of the raw product. There was no recovery of texture during the standing period at atmospheric pressure after the pressure treatment.