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For sorptional data to be useful in simulation and design purposes, they must be represented by equations valid in the conditions usually found in industrial practice. In this regard sorptional models that include the influence of temperature on desorption and sorption equilibrium values are most valuable. In this article, water desorption and sorption isotherms of rose hip fruits (Rosa Eglanteria) were experimentally determined by the gravimetric method, and from these the isosteric heat of sorption was calculated. According to the ANOVA test carried out for this fruits, no significant differences were found between experimental desorption and adsorption isotherms. Seven models were tested to mathematically represent the moisture content as a function of water activity (aw) in the aw range of 0.11 to 0.85 and temperatures of 20, 40, and 60°C, for further use in process simulation. The five-parameter GAB model was most accurate, with an MRE of ?2,9 % and R2?=?0.989. The values obtained for the isosteric heat of sorption were fitted with a previous published equation, with an MRE%?=??0.05. The isosteric heat of sorption derived from the GAB five parameters equation, for the corresponding monolayer moisture content, only differed by 1.25% with the calculated in this paper. 相似文献
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气调贮藏果蔬品质的影响因素分析 总被引:2,自引:0,他引:2
从果蔬的营养成分、硬度和呼吸作用等指标对果蔬的品质进行了分析;介绍了当今贮藏效果最佳的气调贮藏技术,它通过调节环境的气体成分使得果蔬的呼吸作用减弱,以降低营养成分的消耗,保持果蔬的营养价值和新鲜品质;研究发现,贮藏条件对果蔬品质的影响很大,保证果蔬品质的良好必须有适宜的贮藏条件,贮藏过程中影响果蔬品质的因素有温湿度、空气流速、气体成分、包装和运输等;最后分析了在不同温度、不同时间的贮藏条件下,几种果蔬品质的变化. 相似文献
66.
水果中维生素C含量的测定及比较 总被引:26,自引:0,他引:26
吴春艳 《武汉理工大学学报》2007,29(3):90-91
维生素C是评价水果产品质量的重要客观参数之一。提取了4种水果中的维生素C,并利用2,6-二氯酚靛酚钠(Cl2H6O2NCl2Na)法对其含量进行了测定。结果表明:该测定方法快速、简便、准确,所选4种水果的Vc含量接近标准;柑桔、香蕉、西瓜和葡萄4种水果中Vc的含量依次减少。 相似文献
67.
The antifungal effects of 22 essential oils from Turkish spices, herbs and citrus peel on four foodborne moulds were evaluated for fungistatic and fungicidal activity. The most active oils were wild thyme (Thymus rariflorus L) and thyme (Thymus serpyllum L). Parsley (Penloselinum sativum Hoffin) and savory (Satureja hortensis L) oils were found to be the least active oils. Rhizopus sp displayed the greatest tolerance, and the most sensitive mould was Penicillium chrysogenum. Prolonged incubations reduced the fungistatic and fungicidal effects of oils. It was concluded that some oils may be useful as mould inhibitors at food additive levels. 相似文献
68.
Laura Vera-Ramirez M. Carmen Ramirez-Tortosa Pedro Sanchez-Rovira Cesar L. Ramirez-Tortosa Sergio Granados-Principal Jose A. Lorente 《Critical reviews in food science and nutrition》2013,53(1):49-75
Breast cancer, which presents the highest global incidence of all female cancers, is caused by the interaction of genetic and environmental factors. Among the latter, diet has attracted considerable attention, as it is a modifiable risk factor and thus offers an opportunity to design preventive strategies. Nevertheless, only alcohol consumption has been unequivocally related to increased breast cancer risk. Despite the failure of observational studies in human populations to clearly define the nature of the relationship between specific nutrient exposures and breast cancer risk, in vivo and in vitro studies strongly suggest its existence. Moreover, studies at the molecular level have identified the putative action mechanism by which the nutritional constituents of specific foodstuffs may exert protective or enhancing effects with respect to breast cancer risk. The inadequate experimental design of some observational studies, or the occurrence of measurement errors and/or recall bias during data collection, or insufficient follow-up and subject characterization, may underlie these controversies. By improving the methods used to study the relationship between diet and breast cancer risk, and by applying new technologies linked to novel approaches such as “nutrigenomics,” it might be possible to derive effective recommendations for breast cancer prevention and thus improve anti-cancer treatment. 相似文献
69.
目的:获得柑橘热处理过程中果实内部不同点随时间变化的温度分布规律。方法:从传热的角度研究柑橘皮在热处理过程中的温度变化;提出一种新的方法来计算柑橘皮中的温度传递规律,建立一个新的数学模型来模拟柑橘皮在热处理过程中的温度分布;并重点研究3种柑橘(奉节脐橙、长寿血橙和资阳蜜桔)内部温度场的时空分布。结果:热处理时间随水温的升高呈指数级下降,得到了不同品种柑橘的详细指数关系表达式,并通过数据回归方法提出了柑橘热处理时间与水浴温度之间的函数公式。结论:热处理时间随着水浴温度升高呈指数衰减,过低的水域温度会因传热温差过小导致热处理时间极大延长,增加能源消耗。 相似文献
70.
A.R. Ndhlala A. KasiyamhuruC. Mupure K. ChitindinguM.A. Benhura M. Muchuweti 《Food chemistry》2007,103(1):82-87
The phenolic acid composition of the peel and pulp of the fruits of Flacourtia indica (Burm. f.) Merr., Opuntia megacantha (L.) Mill and Sclerocarya birrea (A. Rich.) Hochst., from Zimbabwe, were analysed using traditional colorimetric as well as HPLC methods. The total phenolics, flavanoids and condensed tannin levels varied with species. Sclerocarya birrea pulp had the highest total phenolics, flavanoids and condensed tannins, i.e., 2262 μg GAE/g, 202 μg catechin/g and 6.0% condensed tannins, respectively. Flacourtia indica pulp contained the least total phenolics, flavanoids and condensed tannins 334 μg GAE/g, 41 μg catechin/g and 1.4%, respectively. There were no significant differences in the total phenolics between the peels and the pulps of the individual fruits. However, significant differences were noted in the flavanoids and the condensed tannins between the peels and pulps of the fruits assayed. Ferulic acid, caffeic acid and vanillic acid were the dominant phenolic acids in the three fruits. There were differences between the phenolic acids in the peels and the pulps of the fruits. 相似文献