Tomato pulp quality from transgenic fruits with reduced polygalacturonase (PG)

The physico-chemical and sensory properties of tomato pulps (i.e. diced tomatoes with 30% tomato juice as packing medium), prepared from transgenic tomato (Lycopersicon esculentum) fruits with reduced levels of polygalacturonase (PG) activity due to the expression of a PG antisense gene, were evaluated. The application of genetic modification yields products that have improved viscosity (40–60%), colour (30–40%) and many sensory attributes in comparison with their conventional counterparts.     

Effect of storage in juice with or without pulp and/or calcium lactate on the subsequent survival of Escherichia coli O157:H7 in simulated gastric fluid

A study was conducted to evaluate the effect of storing Escherichia coli O157:H7 in fruit or vegetable juices with or without pulp and/or calcium lactate, on the bacterial resistance to a simulated gastric fluid (SGF, pH 1.5). Apple, carrot, orange, and tomato juices containing pulp or freed from pulp by filtration were used in this study. Calcium lactate at about 1.4 g/l was added to juices to obtain calcium supplemented juices. Juices with or without pulp and/or calcium lactate were inoculated with E. coli O157:H7 and then were stored at 7 degrees C for 0, 1, 2, or 4 days. The acid resistance of cells stored in juices with or without pulp and/or calcium lactate was determined by incubating in SGF for 90 or 240 min at 37 degrees C. Cells stored in apple juice for 4 days, carrot juice for 2 days, and orange juice for 4 days with pulp only had greater acid resistance, while all cells stored in tomato juice with pulp had greater acid resistance than cells stored in juice without pulp. The D-values of cells stored in supplemented apple and orange juices with calcium lactate declined 1.7-3.5 fold, whereas D-values of cells stored in supplemented tomato juice decreased by about 1.4-fold when compared to cells stored in juice without calcium lactate after exposure in SGF. These results indicate that storing E. coli O157:H7 in juices with pulp had little or no effect on the acid resistance of cells during subsequent exposure in SGF. Calcium lactate supplemented into juices could dramatically decrease the ability of E. coli O157:H7 to survive in SGF, possibly reducing the risk of foodborne illness by juice products.     

番茄浆保温处理的工艺研究

以番茄为原料,研究了保温处理对番茄浆液果胶酶和果胶物质含量等指标的影响。结果表明:保温处理对番茄浆液的可溶性固形物和色泽的影响不明显,果胶含量随着保温温度升高、时间延长和pH增大均呈先上升后下降的趋势;果胶酶活性随着保温温度升高、时间延长和pH增大呈先升高后降低的趋势;原果胶含量随着保温温度升高、时间延长和pH增大均呈先下降后上升的趋势。番茄浆液(pH自然)在50℃水浴中保温2h后灭酶,生成的果胶量最多。     

番茄汁乳酸发酵饮料的研究

本文以番茄为原料,经加工处理,将所得原料进行乳酸发酵。首先筛选适宜于番茄汁乳酸发酵用的菌种,从产品的感官、风味、品质等总体效果评定,认为混合菌种发酵的番茄汁优于单一菌种的发酵。本研究确定了混合菌的组成、配比、接种量;探讨了发酵的最佳温度、时间;提出了番茄汁发酵的工艺流程。制品不添加任何化学防腐剂、色素和香精等。分析结果表明,该制品营养丰富,可作为保健型饮料。     

番茄制品加工工艺研究进展

就近年来国内外在番茄制品加工工艺方面的研究进行了综述。从提高产品粘稠度、浓缩、浸钙硬化等方面 ,分别介绍了微波加热、高压处理、超滤浓缩、反渗透浓缩、冷冻浓缩以及优化浸钙工艺等技术应用于番茄制品加工的研究近况     

保加利亚乳杆菌菊芋复合汁增菌培养基的优化筛选

以菊芋为主要原料,以自行分离选育的高活力保加利亚乳杆菌(Lactobacillus bulgaricus)L.b-DR为试验菌株,研究了在菊芋汁培养基中添加单一营养因子对保加利亚乳杆菌L.b-DR细胞生长量的影响;利用正交试验优化筛选出保加利亚乳杆菌L.b-DR的菊芋复合汁增菌培养基。试验结果表明:在菊芋汁基础培养基中添加番茄汁、乳糖、蛋白胨、碳酸钙,可显著促进试验菌株的细胞生长(P<0.01);利用L934正交试验筛选出菊芋复合汁增菌培养基的最佳配比是:在菊芋汁培养基中添加7.5%番茄汁,1.5%乳糖,1%蛋白胨,0.3%碳酸钙。保加利亚乳杆菌L.b-DR经过复原脱脂乳培养基和液体MRS培养基活化后,以1%(约1×106cfu/mL)接入菊芋汁复合增菌培养基中,37℃培养16h,活菌数可达1.50×109cfu/mL,较对照菊芋汁培养基的活菌数提高23.96倍,与实验室常用的MRS培养基的活菌数相当,而其成本较实验室常用的液体MRS培养基的成本降低了2400元/t。     

几种天然提取物对两株双歧杆菌的增殖作用研究

将4种天然提取物添加到双歧杆菌基础培养基中,通过单因素实验找到可显著提高双歧杆菌活菌数的天然物质,并进行正交实验。结果表明:向婴儿双歧杆菌PBA的基础培养基中加入平菇汁20%,卷心菜汁20%,豆浆20%,胡萝卜汁5%可使双歧杆菌活菌数增加2.78倍,向长双歧杆菌INF的基础培养基中加入10%平菇汁,15%蕃茄汁,15%肝浸汁可使活菌数增加2.95倍,为筛选安全而又低廉的双歧杆菌增殖物质奠定基础。     

Proteolytic fungi isolated from decayed and damaged raw tomatoes and implications associated with changes in pericarp pH favorable for survival and growth of foodborne pathogens

Raw and minimally processed high-acid fruits and vegetables are considered to be at low or no risk for supporting growth of foodborne pathogens. The potential increase in the pH of tissues as a result of fungal growth, however, may enhance the potential for survival and growth. We examined 77 decayed and 138 damaged, raw, ripe tomatoes for the presence of yeasts and molds that produce proteolytic enzymes and other metabolites that can potentially increase the pH of pulp tissue. The pH of decayed and sound radial pericarp tissues (pulp) of decayed tomatoes ranged from 4.7 to 7.8 (mean = 6.2) and 4.3 to 5.8 (mean = 5.0), respectively, whereas the pH of damaged and sound pericarp of damaged tomatoes ranged from 4.2 to 7.8 (mean = 5.2) and 4.2 to 8.0 (mean = 4.9), respectively. The pH of sound pericarp of 8.5% of decayed tomatoes and 3.4% of damaged tomatoes, respectively, was > 5.41. In contrast, the pH of 70% of the decayed tissue and 18% of the damaged tissue was > 5.41. Fungal isolates (n = 371) recovered from decayed and damaged tomatoes on dichloran rose bengal chloramphenicol agar were examined for proteolytic activity on gelatin agar and standard methods caseinate agar. One hundred eight (29%) of the isolates exhibited proteolytic activity on one or both differential media; 96 (89%) were molds, and 12 (11%) were yeasts. The pH of both media increased at the edge of proteolytic fungal colonies. Growth of proteolytic isolates from decayed tomatoes on tomato juice agar (pH = 4.3) and on the surface of tomato juice (pH = 4.1) caused an increase in mean pH values at the colony/medium interface to 7.2 and 6.4, respectively. Results show that some fungi capable of infecting raw tomatoes, as well as the mycoflora incident on tomato surfaces, can increase the pH of pericarp and juice to levels favorable for growth of most foodborne pathogenic bacteria.     

直投式泡菜乳酸菌发酵剂培养基的优化及离心条件的探索

根据番茄汁、马铃薯汁和胡萝卜汁的营养条件和乳酸菌的营养要求,通过正交试验,确定泡菜用肠膜明串珠菌和乳酸乳球菌的最佳培养基。试验结果为:肠膜明串珠菌的最佳培养基为:30%番茄汁、25%马铃薯汁、10%胡萝卜汁;乳酸乳球菌的最佳培养基为:25%番茄汁、35%马铃薯汁、15%胡萝卜汁。结果表明:肠膜明串珠菌和乳酸乳球菌分别以此培养基在34℃下培养24 h,其活菌数可达109cfu/mL以上,大大降低了培养基的成本。选择的最佳离心条件为:4 000 r/min的转速下离心20 min,在此条件下离心存活率最高,为制备直投式发酵剂提供了理论依据。     

枯草芽孢杆菌生产抗菌物质的食品级发酵培养基优化

为得到安全可靠的新型生物防腐剂,用枯草芽孢杆菌发酵食品同时提高其抗菌活性。采用单因素试验和Plackett-Burman试验设计筛选出4 个关键因子为脱脂奶粉、番茄汁、发酵时间和发酵温度;使用Box-Behnken原理设计进行响应面试验确定出最佳培养基配方和发酵条件：小麦粉16.0 g/L、脱脂奶粉20.0 g/L、黄豆粉酶解液200.0 mL/L、番茄汁40.0 mL/L、NaCl 10.0 g/L,装液量50.0 mL、发酵温度32.14 ℃、发酵时间60.0 h。拟合实验模型结果显示：优化后发酵液对荧光假单孢的抑菌圈直径较优化前提高42%,对短小芽孢杆菌的抑菌圈直径较优化前提高47%。     

EFFECT of PULPER-FINISHER OPERATION ON QUALITY of TOMATO JUICE and TOMATO PUREE

Preliminary tests were done on the performance of an existing pulper finisher design with two unadjustable blades. Quality parameters such as consistency index and yield were determined at screen sizes of 0.5, 1.0, 1.5 mm and speeds: 100, 300, 500 and 700 rpm. Design modifications were made on the pulper finisher by addition of another blade and slide tapering of blades to allow smooth flow of material on one direction. Quality parameters such as consistency index, pulp/serum ratio, particle size distribution, total solids and total yield were evaluated. A maximum quality index in terms of total solids, pulp/serum, consistency, particle size distribution was achieved at screen size 1.0 mm and a speed of 700 rpm. Maximum yield of tomato juice however, was obtained with screen size of 1.5 mm and a speed of 700 rpm. Results of the comparative tests done on existing and modified pulper finisher showed that quality and quantity of tomato juice and puree from the modified unit is better and higher. A 3% increase in yield was observed from the modified unit.     

IDENTIFICATION OF A GROWTH FACTOR IN TOMATO JUICE FOR A NEWLY ISOLATED STRAIN OF PEDIOCOCCUS CEREVISIAE

A newly isolated strain (L-73) of Pediococcus cerevisiae showed very slow growth in the Nakagawa medium which has been routinely used for the detection of lactic acid bacteria in the brewery. When the Nakagawa medium was enriched with 2% tomato juice extract or when the medium was prepared with the use of unhopped beer, strain L-73 showed good growth. The growth-stimulating factor in tomato juice was purified by chromatography on a charcoal column and it was finally identified by bio-autography as 4′-0-(β-D-glucopyranosyl)-D-pantothenic acid.     

Viscoelastic Properties of Tomato Juice: Applicability of the Cox–Merz Rule

Tomato is one of the most important vegetables for the food industry. Rheological characterization of food is important for products, equipments, and unit operations design and evaluation. It is necessary for process optimization and high-quality products assurance. However, the works in literature present variable data, and some rheological characterization, as viscoelastic properties, are still scarce. The present work has evaluated the viscoelastic properties of tomato juice, as well as the applicability of the Cox–Merz rule. Tomato juice has shown dominant elastic properties rather than the viscous ones and could be classified as a weak gel (storage modulus higher then loss modulus). Moreover, due to the low pulp content, it has shown low viscoelastic behavior, with small dependency of oscillatory of the storage modulus. The rheological oscillatory and steady-state shear rheological properties of tomato juice were then correlated by two linear modifications on the Cox–Merz rule. The obtained values are in agreement with those described in the literature for other food products. The obtained data are potentially useful for future studies on food properties and process design.     

圣女果百合酸乳制品及其稳定性研究

以圣女果、百合和鲜牛奶(或奶粉)为主要原料,添加白砂糖、稳定剂等辅料,保加利亚乳杆菌和嗜热链菌为混合发酵剂,通过L3(33)正交试验和感官评定,研究生产圣女果百合酸奶的加工工艺及其影响稳定性的因素,并对百合浆料液化和脱苦工艺及圣女果的护色条件进行了探讨.试验结果表明:圣女果浆∶百合汁=5∶5,80％的鲜牛奶,7％的白砂糖,0.3％的果胶或复合稳定剂(0.15％的耐酸CMC、0.15％的果胶),发酵温度为41℃,发酵时间约4h,接种量2％时,酸奶质量最佳.     

Survey of Brazilian tomato products for alternariol, alternariol monomethyl ether, tenuazonic acid and cyclopiazonic acid.

Alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TEA) are secondary metabolites of Alternaria species. Cyclopiazonic acid (CPA) is produced by fungi belonging to the ubiquitous genera of Penicillium and Aspergillus and has been found in a wide range of foods. These toxins were searched for by liquid chromatography with diode-array detection in tomato products processed and sold in Brazil. Eighty samples of tomato products were examined (juice 11, pulp 22, purée 22, paste 24 and whole stewed tomato 1). Eleven brands sold nationwide were covered. TEA was found in seven samples of tomato pulp (39-111 ng/g) and four samples of tomato puree (29-76 ng/g). CPA was found in six samples of pulp (64-178 ng/g) and two samples of purée (36-117 ng/g). Co-occurrence of TEA and CPA was found in two samples of purée and one of pulp. This is the first time that the presence of CPA has been reported in tomato products. Neither AME nor AOH were detected in the samples.     

Development of New Product: Rambutan Pulpy Juice

This study aimed to know the effect of adding pulp in rambutan fruit juice on the characteristics of rambutan juice during storage. Research using the CRD, the treatment were kind of pulp (mandarin and rambutan) and pulp concentration (5%, 7.5%, and 10%). The results showed that the addition of pulp significantly affect the characteristics of rambutan juice (pH, vitamin C, total acid) during storage. Pulpy juice with the most prefered was addition of rambutan pulp as much as 7.5% (w/v) and the addition of citrus pulp as much as 7.5% (w/v) with the score of 3-4 (moderate like - like).     

放射型根瘤菌辅酶Q_(10)发酵助剂的研究

研究了几种促进剂和前体对放射型根瘤菌细胞生长及其辅酶Q10发酵的影响,结果表明,在培养基中适量添加番茄汁、胡萝卜汁、蛋氨酸、VB1和对羟基苯甲酸均可明显提高辅酶Q10的产量。在所试浓度范围内,VB1、胡萝卜汁和蛋氨酸3种添加物最高可使辅酶Q10产量比对照组分别提高25%、18%和13%。     

促进混合培养的保加利亚杆菌和嗜热链球菌生长的物质研究

通过在不同乳酸菌基础培养基中添加营养物质的研究,发现啤酒,番茄汁及ＣａＣｌ２均对混合培养的保加利亚杆菌和嗜热链球菌生长有一定影响。实验结果表明,２．５％啤酒可以促进两菌在全脂牛乳中生长及嗜热链球菌在乳清培养基中生长,５％番茄汁可以促进两菌在服清培养基中生长。ＣａＣｌ对两菌在ＢＬＣ培养液中有一定促进生长作用。     

Non-destructive determination of acid–brix ratio of tomato juice using near infrared spectroscopy

Consumer's acceptance of tomato juice depends on its sourness to sweetness ratio and measuring this is important for quality control and marketing. Traditional methods destroy the samples, are time consuming and cannot be used in continuous packing or bottling systems. A non‐destructive method of quality evaluation, using near infrared (NIR) techniques, was tested, by using a portable NIR measuring unit. Spectra of tomato juice of known acid and brix values were determined and, in the wavelength range 703–1124 nm (NIR), a calibration model for acid–brix ratio (ABR) was developed, by using unscrambler software. When used to predict ABR of tomato juice statistical analysis showed minimal standard error (0.009) and satisfactorily high correlation coefficients (0.92) over the wavelength range 1059.5–1124.8 nm, for both calibration and prediction. These values were hardly different from analytical results and the NIR model has potential for non‐destructive prediction of ABR of tomato juice.     

A study of the production of clarified banana juice using pectinolytic enzymes

Pectinolytic enzyme treatments to increase the yield, reduce the viscosity and clarify the juice obtained from ripe banana pulp were studied. Six commercial enzyme preparations were tested on pulps of different ripenesses. Optimal conditions with respect to enzyme concentration, incubation temperature, time and pH levels are reported for the two most effective enzyme preparations. Clear juice yields of between 55 and 60% (based on pulp weight used) are obtained from pulp incubated at 45°C for 1 hr with 0.01% w/w of enzyme by subsequent centrifugation at 2900 maximal relative centrifugal force for 20 min. This corresponds to a yield of total and reducing sugars present in the pulp of over 75%. Untreated control pulps yield less than 5% of juice under these conditions. Hydraulic pressing of the pulps at 16 kg/cm² gives similar juice yields to those obtained by centrifugation. The juice has an excellent flavour and aroma and provides a possible use for the large quantities of reject bananas available in producer countries.