山药山楂酸奶的贮藏品质及胃肠液环境下的抗氧化性

以山药、山楂及鲜牛乳为原料研制山药山楂酸奶,通过测定其低温（4 ℃）贮藏期间（1 d、7 d、14 d、21 d）乳酸菌活菌数、滴定酸度、黏度、持水性、色差等指标,分析山药山楂酸奶贮藏期间品质的变化;同时测定山药山楂酸奶在胃、肠液的模拟环境条件下对DPPH、ABTS自由基的清除能力。结果表明,低温（4 ℃）贮藏期间的山药山楂酸奶在活菌数、酸度以及抗氧化能力方面均优于对照酸奶,持水力低于对照酸奶。在低温（4 ℃）贮藏1 d时,山药山楂酸奶的DPPH和ABTS自由基清除率分别为94.57%、83.11%,对照酸奶为72.27%、72.87%。低温（4 ℃）贮藏期间,冷藏时间延长以及经过胃肠液环境下均会导致两种酸奶自由基清除率的下降,但山药山楂酸奶在总体上仍然优于对照酸奶。     

Yield and quality effects of electroplasmolysis and microwave applications on carrot juice production and storage

Electroplasmolysis as a pretreatment and microwave heating as an alternative to traditional heating were used in carrot juice production and the effects of these electrical methods on juice quality were investigated. Electroplasmolysis and microwave applications were optimized by response surface methodology. Optimum conditions were these: voltage gradient of 22.2 V/cm and treatment time of 60 s for electroplasmolysis, and flow rate of 90 mL/min with power of 900 W for microwave heating. Production of carrot juice was carried out by using these optimum conditions. After production, carrot juice samples were stored for 4 mo at +4 °C and analyses were performed at monthly intervals. As a result of electroplasmolysis, a 9.7% increase in juice yield was obtained. In addition, 100% pectin methylesterase inactivation was found with the microwave heating application. The results showed that the highest values for quality characteristics, such as antioxidant capacity and total pectin, total phenolic, and total carotenoid contents, were obtained with the combined applications of the electrical methods. In addition, these quality characteristics were protected better in the group of combined applications of the electrical methods (electroplasmolysis + microwave) during storage.     

Quality of mango nectar processed by high-pressure homogenization with optimized heat treatment

This work aimed to evaluate the effect of high-pressure homogenization (HPH) with heat shock on Aspergillus niger, vitamin C, and color of mango nectar. The nectar was processed at 200 MPa followed by heat shock, which was optimized by response surface methodology by using mango nectar ratio (45 to 70), heat time (10 to 20), and temperature (60 to 85 °C) as variables. The color of mango nectar and vitamin C retention were evaluated at the optimized treatments, that is, 200 MPa + 61.5 °C/20 min or 73.5 °C/10 min. The mathematical model indicates that heat shock time and temperature showed a positive effect in the mould inactivation, whereas increasing ratio resulted in a protective effect on A. niger. The optimized treatments did not increase the retention of vitamin C, but had positive effect for the nectar color, in particular for samples treated at 200 MPa + 61.5 °C/20 min. PRACTICAL APPLICATION: The results obtained in this study show that the conidia can be inactivated by applying HPH with heat shock, particularly to apply HPH as an option to pasteurize fruit nectar for industries.     

应用PCR技术鉴定豆奶粉、奶粉及果汁饮料中的有效成分

应用PCR技术对日常生活中几种常见的与人类健康和安全有关的豆奶粉、奶粉及果汁饮料等加工食品中的有效成分,包括大豆凝聚素(Lectin)基因、牛线粒体基因、植物叶绿体rbcL基因以及真核生物中普遍存在的核糖体DNA(18SrDNA)片段等进行检测,建立了这些样品的DNA提取、纯化以及单PCR和二重PCR检测技术体系。结果表明:应用单PCR技术和二重PCR技术检测样品的结果一致,且稳定、重复性好。     

影响浊苹果汁混浊稳定性的因素

对影响混浊苹果汁混浊稳定性的因素进行了综述。总体看来,混浊苹果中可溶性果胶的含量,多酚-蛋白质复合物的形成、酚类的氧化聚合和原花青素的聚合都对悬浮颗粒的尺寸有影响。同时,对今后的研究重点进行了讨论。     

澄清杏汁饮料生产工艺

对澄清杏汁饮料的护色、澄清和配方等工艺做了重点讨论。结果表明：护色用1．5％抗坏血酸、0．25％柠檬酸和0．2％氯化锌能得到良好的效果；澄清的最佳工艺为pH4、酶0．001％、时间40min、温度45℃；产品的配方为杏汁40％、糖10％、柠檬酸0．40％。     

Evaluation of the antioxidant activity of asparagus,broccoli and their juices

Antioxidant activity of asparagus, broccoli and their juices was evaluated using 2,2′-diphenyl-l-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and β-carotene bleaching assays. Asparagus showed greater antioxidant activity than broccoli. Asparagus juice also had greater antioxidant activity than broccoli juice. Methanol and acetone extracts of asparagus and broccoli had significantly greater antioxidant activity than their water extracts. Asparagus and broccoli extracts, as well as their juices, showed no significant difference in total phenolics content. However, asparagus contained more flavonoids than broccoli. The antioxidant activity of asparagus and broccoli extracts demonstrated a linear relationship with their flavonoid content.     

甘蔗的磷酸亚硫酸法澄清工艺条件的优化

文章根据云南省临沧市的甘蔗特点,以该市某甘蔗糖厂的混合汁为研究对象,探讨磷酸亚硫酸法工艺中预灰p H值、磷酸添加量、一次加热温度、硫熏强度、中和p H等5个因素对该地区甘蔗蔗汁的清净效果的影响程度,通过正交试验确定出适合该市甘蔗白砂糖生产的最佳澄清工艺条件。     

浑浊苹果汁加工中影响果汁浊度因素的研究

用从苹果中提取的蛋白和果胶，加入绿原酸和儿茶素，组成模拟体系；往低果胶含量的苹果浑浊汁中加入自制的果胶组成半模拟体系。二者和真实体系的对比研究表明：在果汁加工中，浑浊苹果汁中颗粒的形成和长大的因素有：酶促褐变会产生不溶性色素；活性蛋白质-多酚复合物的形成。果胶对三种体系中蛋白质-多酚复合物的形成和长大有显著的抑制作用。     

桑叶汁抗氧化活性的研究

新鲜桑叶经过热烫、打浆、过滤、真空浓缩干燥,分别以乙醇、丙酮、氯仿、乙醚、石油醚为溶剂,提取浓缩物中抗氧化活性物质。结果表明,在花生油中,这5种有机溶剂和水的提取物均表现出抗氧化作用,以丙酮提取物的抗氧化作用最强,其最适使用浓度为0.10%。0.10%丙酮提取物的抗氧化活性略低于0.02%的茶多酚,但高于0.02%的BHTBHA、维生素C、维生素E。化学分析显示,桑叶汁的抗氧化成分以黄酮、萜类、羟基蒽醌、酚类化合物为主。