不同烹调方法对野生蔬菜品质的影响

研究了漂烫、微波和油炒三种烹调方法对野生蔬菜蒲公英、荠菜一些品质的影响。结果表明，与对照相比，漂烫均导致蒲公英和荠菜的氨基态氮、总酸性物质、维生素C、可溶性糖、亚硝酸盐和硝酸盐含量降低。微波使总酸性物质、可溶性糖、硝酸盐含量增加，氨基态氮、维生素C、亚硝酸盐含量降低。油炒则使总酸性物质、硝酸盐含量增加，氨基态氮、维生素C、可溶性糖、亚硝酸盐含量降低。因此，从对人体健康的角度考虑，在食用蒲公英和荠菜时最好先经过漂烫处理以降低硝酸盐含量。     

EFFECT OF STORAGE AND DACUS INFECTION OF OLIVE FRUITS ON THE QUALITY OF THE PRODUCED VIRGIN OLIVE OIL

Olives from three different locations ( Olea europaea cv. Koroneiki), uninfected or infected by the insect Dacus oleae, were collected and stored at 15°2C for 21 days. Samples were taken at 0, 3, 7, 10, 12, 14, 17 and 21 days following collection. Moisture and oil content of olive fruits and the quality parameters of the extracted virgin olive oil were evaluated. Analytical parameters determined were titratable acidity, peroxide value and the specific extinction coefficients at 232 nm (K₂₃₂ and 270 nm (K₂₇₀). Regression equations and best fitting curves between examined parameters and time were evaluated. Olive oil from fly infected olives had higher initial values and a higher rate of increase of the parameters measured. The only parameter affecting oil quality was K₂₇₀. Maximum storage time within legal limit for K₂₇₀ was 16 days for fly uninfected and 10 days for fly infected olives.     

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.     

EFFECT OF CANDELILLA WAX WITH NATURAL ANTIOXIDANTS ON THE SHELF LIFE QUALITY OF FRESH-CUT FRUITS

ABSTRACT

Films formulated with edible natural waxes extracted from Euphorbia antisyphilitica, and additives Aloe vera (4%), ellagic acid (0.01%) and gallic acid (0.01%) were applied to evaluate their effects on the quality of fresh‐cut fruits stored at 5C and at room temperature (21C) for 6 days. The evaluated characteristics were changes in appearance, weight loss, firmness, color, solid content, pH and water activity (A_w). The additives, combined with the natural wax, demonstrated not to cause apparent damage to the fruits. Generally speaking, the films showed better results in comparison with the control. The treatment with A. vera showed the lowest values in weight loss, water migration, A_w, change in pH and firmness. The ellagic acid coating reduced the color change in a greater proportion. The application of these new edible films to fruits extends their shelf life and increases their antioxidant potential, as well as their nutritional quality.

PRACTICAL APPLICATIONS

Edible films elaborated with a natural wax extracted from Euphorbia antisyphilitica complemented with a potent antioxidant ellagic and gallic acids, and Aloe vera extend the shelf life quality and increase the antioxidant potential, as well as the nutritional quality of fresh‐cut fruits and vegetables, giving way to the possibility of producing nutraceutical products in the form of edible biofilms. Potential applications of these films are very attractive because the components are natural and nontoxic, and they are recommended by their low cost, availability and ease of handling. The possibility of using these films on other food products, not necessarily vegetal in origin, could be assayed.

     

THE EFFECT OF COATINGS AND PROCESSING METHODS ON DEHYDRATED PRECOOKED WHOLE PINTO BEANS QUALITY1

Splitting is a major problem in preparing dehydrated precooked beans. To reduce splitting and improve the product quality of precooked pinto beans, three coating treatments and two processing methods were investigated. Beans were blanched, soaked, steam precooked, coated by dipping in a biopolymer solution, and dehydrated in an air-circulating dryer. Coating beans in a 20% dextrin solution (Lo-Dex 5, M100, or K4484) reduced 43–85% of butterflying (severe splitting) of beans. Steam precooking at 121C/30 min with soaking at 22C/12 h yielded less butterflying than steam precooking at 100C/1 h with soaking at 30C/2 h and 82 C/1 h after coating and dehydration (?3% vs 8%). The former resulted in lower firmness after precooking and rehydration of dehydrated beans, whereas the latter gave beans a more mealy texture and better appearance. The rehydration time of dehydrated precooked beans in boiling water to produce an acceptable firmness was 6–9 min, depending on the processing methods. Coating resulted in darker color and slower rehydration of dehydrated beans.     

提取方法对核桃油提取效果及品质的影响

研究了三种提取方法对核桃油得率、理化性能、总黄酮含量、不饱和脂肪酸含量的影响。结果表明：索氏抽提核桃油得率高（66.46%）;超临界CO2萃取核桃油酸值（0.962mg/g）、过氧化值（0.912mmol/kg）低,总黄酮含量（35.63mg/100g）、不饱和脂肪酸含量高（95.13%）,油脂色泽浅,符合人们对植物油口感的要求。     

EFFECT OF THAWING METHODS ON TEXTURAL QUALITY OF SOUS-VIDE STEWED BEEF ASSESSED BY SENSORY AND INSTRUMENTAL ANALYSES

This study compared four different thawing methods using sensory test with magnitude estimation, preference test with hedonic scale and physical analyses. The four methods were tap‐water, refrigeration, microwave reheating, and boiling‐water reheating. For physical analyses, there were differences (p≤0.001) among treatments in drip loss and expressible juice. For drip loss, the microwave reheated samples were the highest and the refrigeration and tap‐water treated samples were the lowest. For expressible juice, tap‐water and refrigerated samples were higher (p≤0.01) than the microwave and boiling‐water reheated samples. Microwave and boiling‐water reheated samples had higher hardness and cheviness and lower juiciness and fiber‐looseness. The refrigerated and tap‐water thawed samples had reverse sensory properties. Naive panelists preferred the refrigerated and tap‐water treated samples to the microwave and boiling‐water reheated samples for juiciness, tenderness, and overall preference. Physical parameters from textural profile analysis were not different among the thawing methods. Expressible juice was the best indicator for sensory hardness, juiciness, fiber‐looseness and chewiness among the physical parameters. Usually a quadratic regression model fit best when expressible juice was used to predict sensory textural properties.     

IMPACT OF IMMATURE FRUITS ON QUALITY OF PEACH PUREE1

Peaches (Prunus persica L. Batsch) were sampled during the early harvest season to determine the percentage of immature fruits harvested in commercial orchards. The results indicated that the earlier the harvest, the higher the percentage of immature fruits (24%). Six days after the harvest season started, the percentage of immature fruits stabilized to 13%. Removal of immature fruits decreased acidity, increased soluble solid/acidity ratio but did not affect soluble solids content in peach puree. Color was improved by the removal of immature fruits in the cultivar (cv) Baby Gold 5, but no effect was noted in Allgold; puree of the cv Baby Gold 7 showed an improvement in color in 1989 but no effect in 1988.     

聚酯切片质量对FDY可纺性及丝条质量的影响

分析了聚酯切片各项指标如:熔点、粘度、凝胶粒子含量等对涤纶FDY可纺性及丝条质量(如强度、伸度、条干均匀度等)的影响。     

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.     

EFFECT OF HIGH HYDROSTATIC PRESSURE, GAMMA-IRRADIATION AND COMBINATION TREATMENTS ON THE MICROBIOLOGICAL QUALITY OF LAMB MEAT DURING CHILLED STORAGE

The effect of gamma irradiation (1.0 kGy) and high hydrostatic pressure (200 MPa for 30 min), either alone or in combination on the shelf-life of lamb mince meat at 0–3C was studied. Untreated control samples initially had total microbial counts of 10⁵ CFU/g, 10² CFU/g of coliforms and 10⁴ CFU/g of Staphylococcus spp. Coliforms were eliminated by all the treatments . Staphylococcus spp. however, were reduced only by 1 log cycle when treated with irradiation alone and high pressure alone. These species were a mixture of mannitol-fermenting and mannitol-nonfermenting strains. In samples subjected to the combination treatment , Staphylococcus spp. appeared only after 3 weeks of storage and all were mannitol-nonfermenting. On the basis of microbiological and sensory quality, the shelf-life of the control sample was less than 1 week. All treated meat samples had a shelf-life of 3 weeks, but only combination treated samples were free from potentially pathogenic Staphylococcus spp .