Thermal resistance parameters for Shiga toxin-producing Escherichia coli in apple juice

The purpose of the present study was to determine the heat resistance of six non-O157 Shiga toxin-producing Escherichia coli (STEC) serotypes in comparison to E. coli O157:H7 in single-strength apple juice without pulp. The thermal parameters for stationary-phase and acid-adapted cells of E. coli strains from serogroups O26, O45, O103, O111, O121, O145, and O157:H7 were determined by using an immersed coil apparatus. The most heat-sensitive serotype in the present study was O26. Stationary-phase cells for serotypes O145, O121, and O45 had the highest D(56°C)-value among the six non-O157 serotypes studied, although all were significantly lower (P < 0.05) than that of E. coli O157:H7. At 60°C E. coli O157:H7 and O103 demonstrated the highest D-values (1.37 ± 0.23 and 1.07 ± 0.03 min, respectively). The D(62°C) for the most heat-resistant strain belonging to the serotype O145 was similar (P > 0.05) to that for the most resistant O157:H7 strain (0.61 ± 0.17 and 0.60 ± 0.09 min, respectively). The heat resistance for stationary-phase cells was generally equal to or higher than that of acid-adapted counterparts. Although E. coli O157:H7 revealed D-values similar to or higher than the individual six non-O157 STEC serotypes in apple juice, the z-values for most non-O157 STEC tested strains were greater than those of E. coli O157:H7. When data were used to calculate heat resistance parameters at a temperature recommended in U.S. Food and Drug Administration guidance to industry, the D(71.1°C) for E. coli O157:H7 and non-O157 STEC serotypes were not significantly different (P > 0.05).     

Utilising grape juice processing by-products as bulking and colouring agent in white chocolate

In this study, grape pomace (mixture of grape seeds and skins) powder (GPP), obtained from grape processing, was used at different concentrations [10.0 (GPP10), 20.0 (GPP10) and 30.0 (GPP10) g/100 g] in white chocolate formulation for the partial replacement of sucrose. The results indicated that GPP addition at a higher concentration (>10.0 g/100 g) significantly affected the particle size, moisture content, texture and flow behaviour of white chocolate samples (P < 0.05). However, using GPP at a concentration of 10.0 g/100 g had advantages for physicochemical and flow properties. As expected, under simulated in vitro digestion conditions, the bioaccessibility of total phenolic compounds in saliva, gastric juice and intestinal juice for GPP10 samples was significantly higher than the control (P < 0.05). In conclusion, results of the study showed that it was possible to partially replace the sucrose with GPP at a concentration of 10.0 g/100 g in white chocolate formulations.     

Vacuum impregnation on apples with grape juice concentrate: Effects of pressure,processing time,and juice concentration

Apple cubes were subjected to vacuum impregnation using grape juice concentrate. The effect of pressure reduction (VP = 100–500 mmHg), immersion time (t = 10–30 min), and concentration of grape juice (C = 40–60°Brix) on impregnation parameters were evaluated using response surface methodology. Second-order polynomial equations were developed (R² > 0.895) to describe the behavior of water loss, total soluble solids, L*, a*, Hue, total color difference, the color of impregnated/treated areas (A_U/A_OP), antioxidant activity, total monomeric anthocyanin, and dimensionless volume (V/Vo) in the impregnated product. VP had a significant (p ≤ 0.05) effect on mass transfer parameters, color parameters, A_U/A_OP, and bioactive compounds. However, at 60°Brix and 500 mmHg, the lower V/Vo values were reached due to cell disruption. Therefore, it is recommended to use a VP = 500 mmHg and t less than 20 min to significantly impregnate compounds and obtain a product without considerable morphometric modification.     

HACCP管理系统在浓缩梨汁生产中的应用

在浓缩梨汁生产管理中,通过推行HACCP管理系统,对其生产进行规范.要求对整个生产工艺过程中的关键点进行严格的质量控制,以确保产品的质量,同时为其它果蔬浓缩汁提供了有益的借鉴.     

刺葡萄汁饮料生产工艺研究

研究用湖南产刺葡萄试制饮料的最佳护色和澄清工艺.结果表明:刺葡萄饮料的最佳护色工艺为70℃保温5 min.最佳澄清工艺为6000r/min离心10 min.     

A new technique for spray drying orange juice concentrate

A new technique for spray drying concentrated orange juice using dehumidified air as drying medium and maltodextrin as drying agent was developed. A pilot-scale spray dryer was employed for the spray drying process. The modification made to the original design consisted in connecting the dryer inlet air intake to an absorption air dryer. 21 DE, 12 DE, and 6 DE maltodextrins were used as drying agents. Concentrated orange juice was spray dried at inlet air temperatures of 110, 120, 130, and 140 °C and (concentrated orange juice solids)/(maltodextrin solids) ratios of 4, 2, 1, and 0.25. Data for the residue remaining on the walls were gathered and the powders were analyzed for moisture content, bulk density, rehydration, hygroscopicity, and degree of caking. The combination of maltodextrin addition and use of dehumidified air was proved to be an effective way of reducing residue formation.Industrial relevanceOrange juice powder has many benefits and economic potentials over its liquid counterparts and provides a stable, natural, easily dosable ingredient, which generally finds usage in many foods and pharmaceutical products such as flavoring and coloring agents. However, the dehydration of orange juice is not a simple task. Thus, the objective of this study was to develop a new technique for spray drying orange juice using dehumidified air as drying medium and maltodextrin as drying agent.     

缓冲能力与葡萄汁饮料中原果汁含量关系的研究

对葡萄汁饮料的缓冲系数与原果汁含量之间的关系进行了研究,结果表明,缓冲系数与原果汁含量呈线性正相关,同时得出了缓冲系数与原果汁含量之间的关系式。只要测定出该饮料的缓冲系数,即可根据关系式推算出该饮料中原果汁含量。该方法的相对标准偏差0.37%~1.13%,回收率106%~108%,具有较高的准确度和精确度,且方法简便、快速,可用于葡萄汁饮料中原果汁浓度的检测。     

HACCP管理系统在胡萝卜浓缩汁生产中的应用

在胡萝卜浓缩汁的生产管理中，通过推行HACCP管理系统，制定生产工艺过程中相应的危害分析及关键控制点，关键限值的监控和纠偏措施，应用于生产实践，对产品安全卫生的提高起到了显著的作用，取得了良好的效果，同时为其它果蔬浓缩汁提供了有益的借鉴。     

二氧化硫在葡萄汁中的作用

SO2在葡萄汁中主要以两种形式存在：游离SO2和结合SO2。许多研究研究表明，游离SO2在葡萄汁中起到杀菌和澄清的作用；SO2与空气中的氧气或葡萄汁中的还原物质结合不仅起到了抗氧的作用，还提高了酸度，增加了浸提效果，对葡萄汁的色泽及香气产生良好的影响。     

苹果浓缩汁后混浊的研究进展

综述了苹果浓缩汁后混浊的反应机理、影响因素及抑制方法。     

生物传感器法检测葡萄汁中葡萄糖含量

采用葡萄糖氧化酶与过氧化氢电极,在0.2 mol/L的磷酸盐缓冲液（pH 7.2）和1‰的葡萄糖标准溶液反应体系中,建立葡萄汁中葡萄糖含量检测的生物传感器分析方法。结果表明,在葡萄糖质量浓度为0～1 000 mg/L的范围内生物传感器法测定葡萄糖含量的线性良好;线性回归方程为y=0.994 8x-3.081,相关系数R2=0.999 9;稳定性好,相对标准偏差（RSD）=1.63%;加标回收率为96.0%～102.4%;专一性强,只对葡萄糖进行专一性测定。     

几种制汁葡萄在新疆生长情况调查及果汁品质分析

试验采用田间调查、果汁品质测定等方法对奥托玫瑰(Muscat Ottonel)、康拜尔早生(CampbellEarly)、卡它巴(Catawba)、白香蕉(Triumph)、玫瑰香(Muscat Hamburg)、香槟(Champion)、康太、黑虎香、一品香、郑果25号、柔丁香、黑贝蒂12个制汁葡萄品种在新疆的生长情况及果汁品质进行了相关的研究。结果表明:郑果25号、康太、卡它巴、康拜尔早生、黑贝蒂、黑虎香、一品香、柔丁香、香槟、白香蕉的综合性状优良,具有生长好、抗病性强、果实性状好和果汁品质优良等特点。     

Modulation of thermal resistance of ascospores of Neosartorya fischeri by acidulants and preservatives in mango and grape juice

Minimal thermal processing is desirable for near natural organoleptic and nutritional qualities of fruit based products. In the present investigation, the effect of heat (85°C) in combination with acidulants or common preservatives on inactivation of ascospores of Neosartorya fischeri, a heat resistant mould isolated from grapes, has been studied in mango and grape juice. The ascospores were found to survive for >300 min of heating at 70, 75 and 80°C in these fruit juices and complete inactivation required 120 min of heating at 85°C. The synergistic effect of heat and organic acids or preservatives in fruit juices was noticed. The thermal death rate (1/k_85°C) values did not vary much in the presence of lactic (20), malic (20) and citric (19) acids, but tartaric acid showed least inactivation effect (1/k_85°C=54 min) in mango juice. The 1/k_85°Cvalues for ascospores of N. fischeri in mango juice containing 0·1% of potassium sorbate or sodium benzoate or combination of both at 0·05% were found to be 44, 35 and 29 min respectively. These values were respectively, 32, 13 and 14 min in grape juice. Nearly 50 and 67% of the heating time was reduced by the use of potassium sorbate and sodium benzoate (0·05% each) in mango and grape juice to inactivate 3 log number of ascospores of N. fischeri. These results may be useful in thermal processing of fruit juices.     

甘薯浓缩汁加工过程中营养成分变化的研究

以Vc、甘薯多糖、胡萝卜素以及膳食纤维含量为指标,研究了甘薯浓缩汁在加工过程中的营养成分变化。结果表明,Vc在破碎过程中受到高温水(85～95℃,破碎过程)和剪切力的影响而氧化水解,几乎全部损失;β-胡萝卜素在浓缩和巴氏杀菌的高温处理过程中损失,高达98.6%;可溶性膳食纤维(SDF)受到果胶酶作用使果胶水解,在多级过滤、超滤和膜过滤后,部分不溶性膳食纤维(IDF)被截留,造成浓缩汁中总膳食纤维(TDF)含量减少88.6%;淀粉酶在水解淀粉后生成了大量的麦芽糖和葡萄糖,使甘薯汁中多糖含量增加283.15%。