Characterization of a wild strain of Alicyclobacillus acidoterrestris: heat resistance and implications for tomato juice

This article reports the characterization of a wild strain of Alicyclobacillus acidoterrestris and describes the implications of the heat resistance of this microorganism in tomato juice. The strain (labeled as A. acidoterrestrisγ4) showed pH and temperature ranges for growth typical of the species (3.0 to 6.0 for the pH and 35 to 60 °C for the temperature); heat resistance in tomato juice was as follows: D(T) values of 40.65, 9.47, and 1.5 min (at 85, 90, and 95 °C, respectively) and z-value of 7 °C. A treatment at 70 °C for 15 min was found to be optimal for spore activation, whereas Malt Extract Agar, acidified to pH 4.5, showed good results for spore recovery. Concerning the implications of heat resistance of A. acidoterrestris on tomato juice, high temperatures required for spore inactivation determined a general decrease of the antioxidant activity (increase of the redox potential and reduction of the chain-breaking activity), but not the formation of brown compounds (namely, hydroxymethylfurfural), thus suggesting an effect on the secondary antioxidants (carotenoids and ascorbic acid) rather than on lycopene. PRACTICAL APPLICATION: Alicyclobacillus acidoterrestris is an emerging spore-forming microorganism, capable of causing spoilage in tomato juice. Due to their high thermal resistance, spores could be used as targets for the optimization of heat processing; this article reports on the assessment of thermal resistance of a wild strain of A. acidoterrestris, then focusing on the effect of the thermal treatment necessary to inactivate spores on the quality of tomato juice.     

苦瓜保健乳饮料

对苦瓜汁保健乳饮料的生产工艺，护色、苦味物质的包接工艺以及稳定剂作用效果作了研究。较好地解决了既要尽量保全苦瓜的有效成分，又使其口感被消费者乐于接受的工艺难点。     

果蔬汁牛乳研制的新思路

讨论了目前国内乳制品行业在风味乳方面的现状。概述了莓系列、花卉等几种新新型果蔬汁的生理特性；预测了风味牛乳良好的前景，分析了影响风味牛乳稳定性的几种因素，并提出了相应的措施。对仙人掌、芹菜汁等几种蔬菜汁生理性能也进行了讨论。     

沙棘果汁饮料的研制

以沙棘鲜果为原料进行沙棘果汁饮料配方研究,实验表明沙棘果汁饮料的最佳配方为:沙棘原汁10％,糖8％,CMC 0．08％,香精0．10％,苹果酸0．10％。     

香瓜西瓜复合饮料的研制

采用单因素试验和正交试验,对香瓜西瓜复合饮料的生产工艺条件进行了探讨.结果表明,该复合饮料的原料优化配比为混合果汁（香瓜汁：西瓜汁=1：2）50%、蔗糖1.5%、蛋白糖0.12%、柠檬酸0.24%和0.12%苹果酸;同时加入0.06%CMC-Na、0.03%琼脂、0.06%黄原胶、0.03%海藻酸钠的复合稳定剂,在30MPa压力下均质,并在80℃杀菌20min,可获得较理想的稳定效果;所得的复合饮料具有清爽宜人、酸甜可口、营养丰富等特点.     

搅拌型桑椹酸乳的研制

以桑椹汁和乳粉为主要原料,研制了一种复合型发酵酸乳。从产品感官质量和稳定性入手,应用正交试验法,确定了合理的配方和适宜的发酵工艺条件。结果表明,桑椹酸乳的主要原料的最佳配比为:乳粉与水质量之比为1∶8,桑椹汁添加量7.5%,复合稳定剂为0.15%淀粉+0.03%果胶+0.06%CMC-Na+0.15%海藻酸钠,最佳的发酵工艺条件为:接种量5%,发酵温度42℃,发酵时间2.5h。     

橙汁中挥发性风味成分分析的研究进展

对橙汁的挥发性风味成分分析的研究进展作了简要概述.其中主要包括挥发性风味成分的定性定量以及香气感官阈值分析,以及采用多元统计方法对风味成分进行分析,为橙汁的生产以及品质判别提供参考.     

不同截流分子量的超滤膜和南瓜汁澄清效果的研究

在南瓜澄清汁加工中分别采用PSA1．5、PSA3．0、PSA6．0和PSA8．0四种不同类型的平板超滤膜进行超滤澄清处理。结果表明，四种膜对南瓜汁均有明显的澄清效果，其透光率（λ＝420nm）由原汁的78．9％分别上升为99．4％、98．9％、98．7％和86．9％；除果胶和蛋白质外，膜的截留分子量（MWCO）对可溶性固形物、还原糖、pH、矿质元素和总酸等含量均无显著影响；澄清汁贮存4个月后，只有PSA1．5和PSA3．0超滤汁无沉淀现象产生，稳定性良好。     

桔子果醋的研制

本文介绍了用桔子汁为原料,经酒精发酵和醋酸发酵生产果醋的工艺及其产品的质量特点。     

Effects of controlled atmosphere (CA) storage on pectinmethylesterase (PME) activity and texture of ‘Rocha’ pears

Firmness and pectinmethylesterase (PME) activity were evaluated in pears (cv Rocha) after 9 months of storage in controlled atmosphere (CA) followed by various periods of exposure to air at room temperature. The free calcium content was also evaluated in tissues. Fruit firmness decreased with increasing time of air exposure for all four different CA storage conditions tested. After 9 days of air exposure, fruits stored in 2% O₂ + 1.5% CO₂ were less firm than control fruits (stored in air) and showed higher PME activity. In spite of normal textural changes being observed with increasing time of exposure to air at room temperature, the underlying metabolism might have been affected by CA storage. © 2001 Society of Chemical Industry