酶-热浸提法提高野樱莓出汁率的工艺优化

为了提高野樱莓果汁的出汁率,以野樱莓原果的可溶性固形物含量为基础进行出汁率计算,对野樱莓榨汁工艺进行优化。先采用酶解法第一次榨汁,得到的果渣再采用热浸提法进一步榨汁,分别在单因素实验的基础上,采用正交试验、响应面试验对酶解法、热浸提法的工艺进行优化。结果表明,酶解法提取野樱莓果汁最优工艺条件为酶用量0.20%,酶解时间2 h,酶解温度50 ℃。在此最佳酶解工艺条件下,野樱莓果汁出汁率为77.70%±0.88%;热浸提的最优工艺条件为水料比21:1,浸提温度63 ℃,浸提时间4.2 h。浸提液与酶解后榨汁获得的果汁混合测得总出汁率为94.07%±0.19%。酶法-热浸提后的总出汁率相较于单一榨汁工艺(出汁率57%)提高了37%。     

不同加工工艺对黑莓浆果出汁率及果汁品质的影响

三种取汁方法的实验结果表明,制取黑莓果汁采用酶法液化法,出汁率、果汁澄清度、可溶性固形物含量高;直接榨汁法出汁率和可溶性固形物含量较高,但果汁浑浊;浸提取汁法出汁率低,果汁稀薄,可溶性固形物含量低,但色素获得率高.酶解正交试验结果表明,果胶酶用量0.04%～0.06%,处理时间1～2h,处理温度45～55℃,黑莓浆果出汁率高,果汁得率在80%以上,果汁澄清,质量好,果汁透光率在90%左右.     

超滤法澄清西番莲果汁的研究

以寻求提高西番莲原汁超滤时的渗透通量为目的，用国产芳香聚酰胺膜平板超滤器进行试验，对超滤操作条件，果汁预处理，膜的清洗进行研究。结果表明，西番莲原汁超滤时渗透通量最高的操作压力为0．15MPa，最佳进料速度为22mL/s，操作温度为室温；原汁经海藻酸钠—碳酸钠澄清剂预处理后可以明显增大渗透通量；超滤处理后。原汁的西番莲固有滋味和品质得到较好保留。采用超滤澄清法生产高质量的西番莲原汁是可行的。     

酶法提高青椒出汁率的研究

主要研究果胶酶、纤维素酶、半纤维素酶在提高青椒出汁率中的应用。结果表明，在单一酶试验中，果胶酶提高青椒出汁率效果最好，明显优于纤维素酶和半纤维素酶，纤维素酶次之，半纤维素酶相对较差。在复合酶试验中，果胶酶与纤维素酶按6：1复配，提高青椒出汁率效果最好。其在较佳酶解工艺条件：总酶用量0．0075％、加水量40％、酶解温度55℃、时间50min、pH3．0下，青椒出汁率可达74．4％，比单一果胶酶处理高出13．8％，比未经酶处理（23．4％）高出51％。     

PASSION FRUIT STARCH AND EFFECT ON JUICE VISCOSITY

Starches in the juices of yellow passion fruit, Passiflora edulis f. flavicarpa , and purple passion fruit, P. edulis f. edulis , were isolated and characterized. Starch granule sizes for the yellow variety (7.8 μm) and purple variety (6.4 μm) were similar. Gelation temperature ranges for the yellow variety (58.5–67.0 ° c) and purple variety (58.5–66.5 ° C) were also similar. The amylose content was slightly higher in the yellow variety (8.7%) than in the purple variety (5.8%). Viscosity differences between juices of the two varieties after treatment with heat and α-amylase were attributed to differences in pH and starch content between the yellow variety (pH 2.8, 0.06% starch) and the purple variety (pH 4.2, 0.74% starch). α-amylase was effective in reducing the viscosity of passion fruit juice in which the starches are gelatinized.     

果汁保健酸奶的研制

采用水提法得到了枸杞子和红枣有效成分的提取液,研究果汁保健酸奶的生产配方和最佳生产工艺.得出生产果汁保健酸奶的最佳工艺条件为:90℃～95℃、5 min高温杀菌牛乳,接种量按奶液体积比的3%,在42 ℃下培养3.5 h,分别加奶液质量6%的蔗糖、6%的枸杞汁、6%的红枣汁及0.2%的黄原胶作为稳定剂.     

THERMAL PROPERTIES OF PASSION FRUIT JUICE AS AFFECTED BY TEMPERATURE AND WATER CONTENT

The specific heat, thermal conductivity and density of passion fruit juice were experimentally determined from 0.506 to 0.902 (wet basis) water content and temperatures from 0.4 to 68.8C. The experimental results were compared with existing and widely used models for the thermal properties. In addition, based on empiric equations from literature, new simple models were parameterized with a subset of the total experimental data. The specific heat and thermal conductivity showed linear dependency on water content and temperature, while the density was nonlinearly related to water content. The generalized predictive models were considerably good for this product but the empiric, product‐specific models developed in the present work yield better predictions. Even though the existing models showed a moderate accuracy, the new simple ones would be preferred, because they constitute an easier and direct way of evaluating the thermal properties of passion fruit juice, requiring no information about the chemical composition of the product, and a reduced time of the estimation procedure, as the new empiric models are described in terms of only two physical parameters, the water content and the temperature.     

酶解牛奶与果汁共同发酵制备牛奶果酒饮料的工艺

为了提高牛奶苹果酒的质量和加工水平,选用果酒酵母,采用蛋白酶水解技术和酒精发酵联用技术对酶解牛奶与苹果汁共同发酵制备牛奶果酒饮料工艺进行研究.通过单因素试验和正交试验获得最佳发酵条件.结果表明,在糖度为12%,发酵温度为30℃,发酵时间为60 h时,牛奶果酒口味较好,此时酒度为2.761 g/100mL,酸度为68 °T,糖度为7.415g/100mL.然后添加适量蔗糖调整糖度为10g/100mL,添加0.1%复合香精进行饮料调配,效果最好.该法生产的牛奶果酒具有口感好、有营养、稳定性好、酒精度低等特点.     

METHODS FOR DETERMINING THE FERMENTABILITY AND PREDICTED SPIRIT YIELD OF DISTILLING MALTS

Fermentability and predicted spirit yield (PSY) are two fundamental quality parameters of distilling malt, both of which rely on empirical factors for their calculation. Experiments were carried out using modern barley varieties to assess whether these factors were still valid for use in today's distilling industry. Using the 450 g IOB mash, an average attenuation factor of 81.46 from fifty-two determinations was found which was not significantly different from the existing factor of 81.4. A novel method to calculate the attenuation factor at different alcohol strengths was demonstrated which confirmed the factor to be 81.46. The PSY factor was shown to be 6.11 for a 450 g IOB mash, calculated using methods based on predicted and actual alcohol produced. However, a high gravity mashing procedure which more closely simulated distillery conditions confirmed that the current standard factor of 6.06 was still acceptable. Results indicated that it was not necessary to change either the attenuation or PSY factors when changing from the 515 ml mash to the 450 g mash in the standard IOB Recommended Methods.     

树脂在现代果汁加工中的应用

树脂的发展经历了沸石、磺化媒、磺化酚醛树脂、凝胶聚苯乙烯、聚丙烯酸到大孔离子交换树脂和吸附树脂的过程。现在，树脂在工业生产、生化医疗、环境保护、食品制造，还有国防军事、原子能研究等很多方面都有应用。随着一些新型树脂的问世，它的用途越来越广泛，详细介绍了树脂在果汁加工中的应用。