预处理对香蕉片质构特性的影响

[目的]优选能够有效改善香蕉果肉质构性质的预处理方法.[方法]选用香蕉为原料,探讨了热烫处理、外源钙离子、果胶甲酯酶及复合处理对鲜切香蕉片质构特性的影响.[结果]试验表明,果胶甲酯酶复合热处理对香蕉片硬化效果较理想,在添加0.005％果胶甲酯酶（以浸泡液质量计）时,香蕉片硬化效果最优.相较于其他处理方式,香蕉片硬度、弹性和咀嚼性得到了明显的改善.[结论]该试验可为香蕉深加工工艺的研究提供理论基础.     

芦笋热烫介质的选择及工艺优化研究

[目的]对比选择适合芦笋的热烫介质并优化热烫工艺.[方法]以新鲜绿芦笋为原料,对水、油、水油3种常见的热烫介质进行对比研究,选择最佳热烫介质.在单因素试验的基础上,分别以芦笋的抗氧化活性、干物质溶出率及感官性状为指标,通过k（34）正交设计优化芦笋热烫的工艺条件.[结果]试验表明,水油为芦笋的最佳热烫介质,且芦笋热烫的最佳工艺条件为：水油比12∶1 ml/ml,料液比1∶3 g/ml,在100℃下烫制2min.在此条件下,芦笋的抗氧化活性最高,色泽最好,且食用品质达到最佳水平,干物质溶出率为1.28％.[结论]以水油为热烫介质的芦笋适宜于加工各种菜肴,且研究可为指导人们合理烹调提供理论依据.     

响应面优化小米辣椒烫漂工艺研究

[目的]为改善小米辣椒泡制品质,优化小米辣椒漂烫工艺.[方法]采用烫漂处理对新鲜小米辣椒多酚氧化酶进行钝化,通过单因素试验考察烫漂温度、烫漂时间以及液料比3个主要因素对小米辣椒多酚氧化酶相对酶活和硬度的影响.在此基础上设计响应面试验优化漂烫工艺.[结果]通过分析得出小米辣椒漂烫最佳工艺:烫漂温度87.94℃、烫漂时间43.99 s和液料比3.5∶1 ml/g时,可以在保证较高硬度(61.76 N)的基础上使多酚氧化酶活性降低80.62％.[结论]研究建立了小米辣椒烫漂工艺的回归模型,可为小米辣椒的深加工提供一定的参考依据.     

Quality indices of Jew's mallow and spinach during frozen storage

In this study, Jew's mallow and spinach were heat treated and kept frozen, at –18°C, for 3 months. Analysis of some chemical components and enzymatic activities as well as a sensory evaluation were undertaken. At the end of the storage period, blanched spinach showed no PPO (polyphenyloxidase) activity at all, but still contained PO (peroxydase) and LO (lipoxygenase) activities. The untreated spinach stored under the same conditions showed high activities of PO, PPO and LO. The heat treated mallow still contained high enzyme activities which decreased slowly during frozen storage. Statistical analysis of the chemical composition and the sensory evaluation results indicated that heat treatments of mallow caused significant differences in total solids, pH, chlorophylla and total chlorophyll, while frozen storage, of samples of the same treatment for 3 months caused no significant differences in moisture, ash, oxalic acid, pH, chlorophylla and total chlorophyll. No significant differences could be noticed in the overall acceptability between mallow samples mixed with hot water and those mixed in the overall acceptability between mallow samples mixed with hot water and those mixed with a hot 0.1% MgCO₃ solution. Significant differences were found between the heat treated and the untreated mallow. Changes of the chemical composition and the overall acceptability of blanched spinach during frozen storage showed almost the same trend noticed for the Jew's mallow.     

热烫拉伸条件对乳扇拉伸性能和出品率的影响

本研究利用热处理的酸乳清对牛乳进行预酸化处理,研究不同热烫条件对乳扇热拉伸性和产量的影响,并对工艺条件进行优化。结果表明,乳扇热烫拉伸最佳工艺条件为温度70℃、pH6.0,该条件下乳扇的拉伸性较好并且出品率较高（7.11%）。     

Microwave drying of selected greens and their sensory characteristics

Green leafy vegetables which supply minerals and vitamins to the diet, are highly perishable. Therefore, post harvest losses are extremely high. Limited studies are available in the literature with regard to preservation of greens.The effect of microwave drying and storage on physical and sensory properties of selected greens (coriander, mint, fenugreek, amaranth and shepu) were therefore studied. Microwave drying was carried out at 100% power and a frequency of 2450 mHz. The drying time varied from 10 to 16 min for different greens. Microwave drying affected color, appearance and odor of all the greens. The relative reconstitution capacity (RRC) for different greens was coriander-10.3, mint-10.3, amaranth-38.3, fenugreek-31.7 and shepu-32.8. The RRC appeared to influence acceptability. Coriander and mint, which exhibited the lowest RRC (10.3%), had the lowest scores for flavor and color while amaranth, with the highest RRC (38.3%), had scores similar to those of fresh amaranth. Scores for the products prepared with dried fenugreek and shepu,although low, were not statistically significant. Microwave drying was highly suitable for greens such as amaranth; moderately suitable for shepu and fenugreek and less suitable for coriander and mint.     

芹菜营养保健香肠的开发研究

与西红柿、胡萝卜比较,确定将芹菜添加到香肠中。研究表明,芹菜的最适烫漂温度为95℃,时间为1.5 min,护色液为Zn(Ac)2400 mg/kg。通过正交试验得到芹菜香肠最佳配方:芹菜添加量5%,猪肥肉与猪瘦肉的添加比例1∶9,淀粉添加量8%。     

Blanching of green bean (Phaseolus vulgaris)

Experiments with one and two steps blanching of green beans have been carried out. Inactivation of the peroxydase requires more heating than inactivation of the enzymes which gives rise to off flavour from aldehydes. When blanching for about one minute to inactivate lipoxygenase, aldehyde formation of flavour ceases. The content of vitamin C decreases during blanching according to a first order reaction. Since considerable loss of vitamin C occurs during blanching, the treatment time should be reduced to a minimum. During preblanching at 65–75 °C and final blanching, chlorophyll is degraded to pheophytin and the surface colour expressed by the Hunter-values (–a/b) increases with time which means that the colour of the beans changes from green to yellow. The firmness of beans, which was measured by use of a tenderometer, decreases during blanching according to a first order reaction with 40 kcal/mole activation energy. Preblanching at 65–75 °C increases the firmness of the beans linearly with treatment time. This increase in firmness is stable after final blanching at 95 °C and even after thawing of frozen beans.     

Effect of home processing on ascorbic acid and β-carotene content of spinach (Spinacia oleracia) and amaranth (Amaranthus tricolor) leaves

The present investigation was conducted to study the concentration of ascorbic acid and -carotene in spinach and amaranth leaves as affected by various domestic processing and cooking methods which included storage of leaves in polythene bags or without packing for 24 and 48 hours in refrigerator at 5 °C; at 30 °C in polythene bags; drying (sun and oven); blanching (5, 10, 15 min); open pan and pressure cooking. Ascorbic acid content of fresh leaves was 624.1 to 629.0 mg and -carotene content was 35.3 to 53.1 mg/100 g dry weight. The percent loss of ascorbic acid ranged from 1.1 to 6.3 and 55.3 to 65.9 while lower losses (0.0 to 1.3 and 1.5 to 2.1) of -carotene were observed in leaves stored in refrigerator and at 30 °C, respectively. A markedly greater reduction in ascorbic acid and -carotene was observed in dried, blanched and cooked leaves. The study recommended the storage of leaves in refrigerator, drying in oven, blanching for shorter time and cooking in pressure cooker for better retention of these two vitamins.     

Effect of traditional processing practices on the content of total carotenoid, β-carotene, α-carotene and vitamin A activity of selected Tanzanian vegetables

The α-carotene, β-carotene and total provitamin A carotenoids and the effect of traditional processing practices on the retention of these provitamins were studied using amaranth, cowpea, peanut, pumpkin and sweet potato leaves. Results of this study indicated that the content of total carotenoids, β-carotene and α-carotene were in the range of 26.79–44.74 mg, 4.16–19.12 mg, and 0.99–10.26 mg per 100 g of dry vegetables, respectively. The vitamin A activities were 4.042, 3.124, 0.829, 2.025 and 1.581 mg RE per 100 g of dry amaranth, cowpea, peanut, pumpkin and sweet potato leaves, respectively. The traditional processing practices of sun drying and storage in ventilated containers resulted in a significant (p<0.05) decrease in the concentration of total carotenoids, β-carotene and α-carotene for all the vegetables. Conventional blanching and cooking resulted in a significant (p<0.05) increase in the concentration of carotenoids in the cowpea, peanut and pumpkin leaves while in amaranth and sweet potato greens, thermal processing resulted in a significant (p<0.05) decrese in the concentration of these nutrients.