Osmotic Dehydration and Vacuum Impregnation on Physicochemical Properties of Chilean Papaya (Carica candamarcensis)

ABSTRACT: The effect of osmotic dehydration (OD) at atmospheric pressure and vacuum impregnation (VI) treatments on some physiochemical parameters of papaya (aw, pH, color, firmness, and microstructure) was analyzed. Osmotic treatments were carried out on papaya with 55°Brix and 65°Brix sucrose solutions at 30 °C. VI with 65°Brix osmotic solution was the most effective in reducing aw due to the highest sucrose gain during osmotic treatment. Color differences were associated to loss of clarity in line with transparency gain. Scanning electron microscopy observations show that osmotic dehydration caused shape changes and size reduction of papaya cells; also differences in microstructural features were observed between OD-treated and VI-treated samples. Moreover, the largest firmness observed in VI samples compared with OD treatments was associated with the thickness of the middle lamella between cells, which was greater in VI than OD treatments. Improvement in texture and palatability of papaya was obtained with VI rather than OD treatment compared with fresh papaya.     

天然物质对切割蔬菜中常见微生物的抑制作用研究

研究了正离子水和姜黄、虎杖、艾叶、丁香提取物对切割蔬菜中常见微生物(大肠杆菌、荧光假单胞菌、啤酒酵母)的抑制作用,结果表明:正离子水对大肠杆菌、荧光假单胞菌、啤酒酵母无抑制作用,抑制率均为0;姜黄、虎杖、艾叶、丁香提取物对3种微生物均有一定的抑制作用。适宜温度培养7d后,姜黄、虎杖、艾叶、丁香提取物对大肠杆菌的抑制率从大到小依次为:姜黄(51.7%),艾叶(37.2%),虎杖(36.5%),丁香(30.4%);对荧光假单胞菌的抑制率从大到小依次为:丁香(100%),姜黄(55.8%),艾叶(55.8%),虎杖(46.7%);对啤酒酵母的抑制率从大到小依次为:丁香(100%),姜黄(35.3%),艾叶(35.3%),虎杖(33%)。     

Microbial Population of Shredded Carrot in Modified Atmosphere Packaging as Related to Irradiation Treatment

Shredded carrots in modified atmosphere packaging were treated with low-dose irradiation of 0.5 kGy in order to determine whether additional reduction of microbial population would be achieved for carrots previously treated with chlorine. Commercially prepared shredded carrots treated with irradiation had a mean microbial population of 1300 CFU/g at the expiration date (9 days after irradiation) compared with 87,000 CFU/g for nonirradiated, chlorinated controls. Oxygen content of the headspace gas and ethanol content of the carrots were not significantly affected. Irradiation appears to be a suitable technology for shredded carrots.     

再制干酪贮藏期间的物理及化学变化

再制干酪往往被认为是一种保质期较长的、稳定的干酪食品。事实上，再制干酪即便不被微生物污染，室温下的保质期也只有几个月。贮藏期间，再制干酪的质地和风味都慢慢改变，本文阐述了引起储藏期间再制干酪质地和风味变化的主要原因，对引起这些变化的因素加以分析．并概括了国外关于再制干酪储藏期的研究进展。通过对再制干酪贮藏期质地变化的研究，将有助于干酪生产者更好的预测和控制产品贮藏期间的质量。     

果冻类样品中非法添加物质2种提取方法比较

目的比较常规加热法和粉碎离心法对果冻类样品中非法添加物质的提取效果。方法以常见的2种降糖类、4种减肥类和3种利尿类非法添加化学物质为研究对象制备基质加标阳性样,样品经加热和粉碎离心处理后采用超高效液相色谱串联质谱仪测定,外标法定量,以基质效应、回收率和精密度为指标考察2种方法的提取效率。结果加热处理下样品的回收率为31.27%~135.50%,精密度为0.75%~16.40%,经粉碎离心提取处理下的样品中的9种非法添加化学药物回收率为51.60%~116.90%,精密度为1.63%~10.70%,粉碎离心处理下样品的基质效应也低于加热处理。结论相较于加热提取法,粉碎离心提取法操作简便、结果稳定可靠、灵敏度高,可用于果冻类胶质样品的样品前处理。     

Improvement of frozen banana (Musa cavendishii, cv. Enana) colour by blanching: relationship between browning, phenols and polyphenol oxidase and peroxidase activities

 Browning in banana (Musa cavendishii, cv. Enana) processed products is a result of phenol oxidation catalysed by polyphenol oxidase (PPO) and peroxidase (POD) or of other non-enzymatic reactions (Maillard and Strecker mechanisms). Microwave and steam blanching significantly reduced PPO and POD activities and phenol levels in banana flesh, steam blanching being the most effective method for enzyme inactivation. Freezing/thawing processes produced a significant increase in phenol levels in all samples, due to cellular breakdown. After microwave heating browning processes occurred while steam-treated samples did not exhibit a significant colour change. Extractable PPO and POD activities in all banana samples increased as a consequence of freezing/thawing: steam-blanched slices exhibited lower residual activities. High correlations occurred between phenols and browning (r=0.86) in control samples. Blanched samples (microwave or steam) only exhibited correlations between PPO (r=0.80) and POD (r=0.80) activities and browning. Received: 22 February 1996     

Improvement of frozen banana (Musa cavendishii, cv. Enana) colour by blanching: relationship between browning, phenols and polyphenol oxidase and peroxidase activities

 Browning in banana (Musa cavendishii, cv. Enana) processed products is a result of phenol oxidation catalysed by polyphenol oxidase (PPO) and peroxidase (POD) or of other non-enzymatic reactions (Maillard and Strecker mechanisms). Microwave and steam blanching significantly reduced PPO and POD activities and phenol levels in banana flesh, steam blanching being the most effective method for enzyme inactivation. Freezing/thawing processes produced a significant increase in phenol levels in all samples, due to cellular breakdown. After microwave heating browning processes occurred while steam-treated samples did not exhibit a significant colour change. Extractable PPO and POD activities in all banana samples increased as a consequence of freezing/thawing: steam-blanched slices exhibited lower residual activities. High correlations occurred between phenols and browning (r=0.86) in control samples. Blanched samples (microwave or steam) only exhibited correlations between PPO (r=0.80) and POD (r=0.80) activities and browning. Received: 22 February 1996     

一种改进的理想滤波器方位模糊抑制方法

合成孔径雷达(SAR)图像的方位模糊问题是由于方位向欠采样引起的,其严重影响判读人员对SAR图像的解译.阐述了方位模糊的来源及其建模,进一步总结了利用理想滤波器进行方位模糊抑制的方法及其局限性,针对该方法的参数失配问题,从主像和模糊像在方位向和距离向上的偏移距离的角度出发,提出并明确分块处理大区域方位模糊抑制的思路及分...     

复合乳化剂防止常温贮藏再制干酪油脂析出的研究

为解决常温贮藏再制干酪加工过程及贮藏期间的油脂析出问题,本研究以油析性为评定指标,从6种乳化剂中筛选出4种效果较好的乳化剂,在确定常温贮藏再制干酪最适亲水亲油平衡值(HLB值)后,根据HLB值将不同乳化剂进行复配,得到了1种最佳组合的复合乳化剂配方.结果表明,最适HLB值为12.2,复合乳化剂最佳配比(均为质量分数):14％单甘脂,30％六聚甘油单硬脂酸酯,56％的蔗糖脂肪酸酯,乳化剂总用量为0.4％.同时将样品置于(22±2)℃条件下,贮藏90 d,定期检测产品油性变化,均小于对照组,且差异显著(P＜0.05),说明添加该复合乳化剂有效.