Efficacy of Integrated Treatment of UV light and Low‐Dose Gamma Irradiation on Inactivation of Escherichia coli O157:H7 and Salmonella enterica on Grape Tomatoes

The study evaluated the efficacy of integrated ultraviolet‐C light (UVC) and low‐dose gamma irradiation treatments to inactivate mixed strains of Escherichia coli O157:H7 and Salmonella enterica on inoculated whole grape tomatoes. A mixed bacterial cocktail composed of a 3 strain mixture of E. coli O157:H7 (C9490, E02128, and F00475) and a 3 serotype mixture of S. enterica (S. Montevideo G4639, S. Newport H1275, and S. Stanley H0558) was used based on their association with produce‐related outbreaks. Spot inoculation (50 to 100 μmL) on tomato surfaces was performed to achieve a population of appropriately 10^7–8 CFU/tomato. Inoculated tomatoes were subjected to UVC (253.7 nm) dose of 0.6 kJ/m² followed by 4 different low doses of gamma irradiations (0.1 kGy, 0.25 kGy, 0.5 kGy, 0.75 kGy). The fate of background microflora (mesophilic aerobic) including mold and yeast counts were also determined during storage at 5 °C over 21 d. Integrated treatment significantly (P < 0.05) reduced the population of target pathogens. Results indicate about 3.4 ± 0.3 and 3.0 ± 0.1 log CFU reduction of E. coli O157:H7 and S. enterica, respectively, per tomato with UVC (0.6 kJ/m²) and 0.25 kGy irradiation. More than a 4 log and higher reduction (>5 log) per fruit was accomplished by combined UVC treatment with 0.5 kGy and 0.75 kGy irradiation, respectively, for all tested pathogens. Furthermore, the combined treatment significantly (P < 0.05) reduced the native microflora compared to the control during storage. The data suggest efficacious treatment strategy for produce indicating 5 or higher log reduction which is consistent with the recommendations of the Natl. Advisory Committee on Microbiological Criteria for Foods.     

胡萝卜番茄面包的研制

以胡萝卜和番茄酱为原料,胡萝卜经过适当处理制得高品质胡萝卜汁,将胡萝卜汁和番茄酱在面包生产中加入,通过试验探讨了合适的蔬菜面包产品配方、生产工艺,得出它的最佳配方为胡萝卜汁添加量12%,番茄酱添加量3%,白砂糖用量12%,酵母用量1.4%,水用量45%,开发出营养全面、色泽诱人的胡萝卜番茄面包。     

Preparation of High‐Grade Powders from Tomato Paste Using a Vacuum Foam Drying Method

We present a rapid and gentle drying method for the production of high‐grade tomato powders from double concentrated tomato paste, comparing results with powders obtained by foam mat air drying and freeze dried powders. The principle of this method consists of drying tomato paste in foamed state at low temperatures in vacuum. The formulations were dried at temperatures of 50, 60, and 70 °C and vacuum of 200 mbar. Foam stability was affected by low serum viscosity and the presence of solid particles in tomato paste. Consequently, serum viscosity was increased by maltodextrin addition, yielding optimum stability at tomato paste:maltodextrin ratio of 2.4:1 (w/w) in dry matter. Material foamability was improved by addition of 0.5% (w/w, fresh weight) egg white. Because of solid particles in tomato paste, foam air filling had to be limited to critical air volume fraction of Φ = 0.7. The paste was first pre‐foamed to Φ = 0.2 and subsequently expanded in vacuo. After drying to a moisture content of 5.6% to 7.5% wet base (w.b.), the materials obtained were in glassy state. Qualities of the resulting powders were compared with those produced by freeze and air drying. Total color changes were the least after vacuum drying, whereas air drying resulted in noticeable color changes. Vacuum foam drying at 50 °C led to insignificant carotenoid losses, being equivalent to the time‐consuming freeze drying method. In contrast, air drying caused lycopene and β‐carotene losses of 18% to 33% and 14% to 19% respectively. Thus, vacuum foam drying enables production of high‐grade tomato powders being qualitatively similar to powders obtained by freeze drying.     

番茄果酒酿造酵母菌的筛选研究

以筛选适宜的酿造番茄果酒的酵母为研究目标,通过TTC显色法初筛及产气复筛、大瓶发酵,对来源于自然发酵的番茄汁中的酵母菌进行优选,得到一株优良的酵母菌株。发酵结果表明,该酵母菌能耐受较高的糖浓度和酒精度,适合在番茄汁pH中进行正常产酒发酵。由于该酵母菌优良的特性,因此可以作为菌种酵母进行番茄酒的酿造。     

番茄果实打浆温度对番茄酱中果胶物质的影响

通过研究热打浆和冷打浆番茄酱中低分子糖类物质和水溶性多糖类物质的变化,探讨了番茄果实打浆温度对番茄酱果胶物质的影响。糖分析结果表明,热打浆和冷打浆番茄酱中低分子糖的组成比例有明显的差异;热打浆番茄酱水溶性多糖(HPS)和冷打浆番茄酱水溶性多糖(CPS)均为果胶物质,但是HPS的得率以及半乳糖醛酸含量明显高于CPS。凝胶柱层析分析结果显示,HPS中高分子果胶物质比例较高,而CPS中低分子果胶物质的比例较高。番茄酱加工过程中番茄果实打浆温度对番茄酱果胶物质有显著的影响。     

超声波辅助萃取豆渣中可溶性大豆多糖工艺

对豆渣中水溶性大豆多糖进行超声辅助萃取,以获得其超声辅助萃取大豆豆渣多糖的优化工艺。以豆渣为原料,在pH值为6.0的条件下,从提取时间、液固比、超声功率及提取温度等因素分析其对豆渣可溶性大豆多糖得率的影响,并通过正交试验优化超声波辅助萃取豆渣中可溶性大豆多糖的工艺。最佳萃取工艺条件为:液固比20∶1、温度60℃、时间30min及功率70W。此条件下豆渣中可溶性大豆多糖提取率可达到最大,为0.019%。在影响大豆豆渣多糖提取率的4个因素(提取温度、液固比和提取时间、超声功率)中,液固比、提取时间为主要因素,其次是温度和超声功率。超声波辅助萃取可有效提高豆渣中可溶性大豆多糖得率。     

Energy Consumption, Density, and Rehydration Rate of Vacuum Microwave- and Hot-Air Convection- Dehydrated Tomatoes

ABSTRACT: Vacuum to lower boiling temperature and microwaves for energy transfer can provide very rapid dehydration at low temperatures. Tomato sections were dehydrated in a batch convection air dryer (AD), a 16 kW vacuum microwave (VM) dryer, or by 1 of 3 combination processes. Drying rate of the 100% VM process was 18 times that of the 100% AD process. Only a slight falling rate effect was noted in VM drying AD and VM in sequence allowed the operator to choose any process time between 0.8 and 14.75 h. In this instance the least energy consumption occurred in the 100% VM process. Lowest energy cost was found for the 70% AD / 30% VM process. These results are expected to be strongly dependent upon the scale and design of dryers. Tomatoes finish-dried by VM exhibited a puffed structure associated with faster rehydration.     

Effects of Ultrasound on Spoilage Microorganisms,Quality, and Antioxidant Capacity of Postharvest Cherry Tomatoes

Mature‐green cherry tomato fruits (Lycopersicon esculentum cv. Jinyu) were exposed to different power densities of ultrasound (66.64, 106.19, and 145.74 W/L) at 25 °C to study ultrasound non‐thermal effects on the storage properties. Among the three levels of ultrasound irradiation, 106.19 W/L ultrasound was effective in reducing the spoilage microorganisms, delaying postharvest ripening through inhibiting ethylene production and respiration rates, and consequently maintaining fruit firmness, flavor, enzyme activities, antioxidants (total phenolics, total flavonoids), and the total antioxidant capacity of cherry tomatoes. The 66.64 W/L ultrasound had similar effects but to a lesser extent. Meanwhile, although 145.74 W/L ultrasound resulted in higher content of ascorbic acid (AA), it showed many negative effects on the storage quality of fruits. These results demonstrated that ultrasound of appropriate power density had great potentials in inhibiting decay, maintaining flavor and nutritional quality of cherry tomatoes.     

Crop drying by indirect active hybrid solar – Electrical dryer in the eastern Algerian Septentrional Sahara

In the present work, a new specific prototype of an indirect active hybrid solar–electrical dryer for agricultural products was constructed and investigated at LENREZA Laboratory, University of Ouargla (Algerian Sahara). In the new configuration of air drying passage; the study was done in a somewhat high range of mass flow rate between 0.04 and 0.08 kg/m² s a range not properly investigated by most researchers. Experimental tests with and without load were performed in winter season in order to study the thermal behavior of the dryer and the effect of high air masse flow on the collector and system drying efficiency. The fraction of electrical and solar energy contribution versus air mass flow rate was investigated. Slice tomato was studied with different temperatures and velocities of drying air in order to study the influence of these parameters on the removal moisture content from the product and on the kinetics drying and also to determine their suitable values. Many different thin layer mathematical drying models were compared according to their coefficient of determination (R²) and reduced chi square (χ²) to estimate experimental drying curves. The Middli model in this condition proved to be the best for predicting drying behavior of tomato slice with (R² = 0.9995, χ² = 0.0001). Finally an economic evaluation was calculated using the criterion of payback period which is found very small 1.27 years compared to the life of the dryer 15 years.     

应用纤维素酶解和酸洗法从米渣中提取蛋白质的研究

该文研究了纤维素酶水解和酸洗法相结合，从大米糖化渣中提取食用蛋白质的新工艺。纤维素酶水解最佳条件为温度50℃，pH4．8—5．0，纤维素酶用量2μ/g—40μ／g米渣，酶解时间30min-60min；酸洗法以二级酸洗提取效果较好，提取最佳条件为温度30℃，时间6min，料液比1：6；用纤维素酶水解和二级酸洗两步法提取，得到产品蛋白含量最高达86．8％。