真空包装腌萝卜干中腐败微生物的抑制研究

实验用苯甲酸钠、山梨酸钾、尼泊混合酯、脱氢醋酸钠、双乙酸钠5种防腐剂,抗氧化剂植酸,酸味剂富马酸、水分保持剂六偏磷酸钠、乳化剂蔗糖酯以及复合防腐剂对真空包装腌萝卜干中6种腐败微生物(克柔念珠菌、枯草芽孢杆菌、蜡样芽孢杆菌、金黄色葡萄球菌、表皮葡萄球菌和短乳杆菌)进行了抑制试验,并研究了氯化钠、乙醇、pH对腌萝卜腐败微生物的押制作用.结果表明:pH为4.0,6%氯化钠,5%乙醇对腌萝卜干腐败微生物有较好抑制.单一防腐菌抑菌效果不理想.双乙酸钠、富马酸、尼泊混合酯的抑菌效果相对较好,脱氢醋酸钠对表皮葡萄球菌和短乳杆菌的抑制较强.脱氢醋酸钠+富马酸组合、双乙酸钠+富马酸组合、脱氢醋酸钠+双乙酸钠组合综合抑菌效果好.     

豆干制品防腐应用研究

本文应用防腐栅栏原理对豆干制品进行防霉防腐研究。研究表明：豆干制品坯料选用0．003％二氧化氯消毒，并以脱氢醋酸钠、尼泊金复合酯、双乙酸钠、天然物、复合乳化剂、防腐增效剂等组成的复合防腐剂0．10％-0．25％．于卤水中沸腾状态保持25min后捞出，晾干，麻辣调料用160℃以上热油浸泡加以杀菌，并加入迎龙中性食品防腐剂C型0．10％处理，装袋，抽空后于95—98℃水中杀菌25min。擦干水分，常温下180d内符合食品卫生要求。     

聚赖氨酸对鲜榨玉米汁保鲜效果的研究

通过单因素试验和正交试验,确定了聚赖氨酸在玉米汁饮料中的最大使用量、最佳使用量,并确定了在玉米汁饮料中与聚赖氨酸组合的最佳制剂以及复配防腐剂的最佳配方。试验结果为：玉米汁饮料中使用聚赖氨酸的最大范围是0．02％;玉米汁饮料中单独使用聚赖氨酸的最适量为0．003％;玉米汁饮料添加最适聚赖氨酸浓度为0．003％,甘氨酸浓度为0．5％;防腐剂复配最佳组合为0．003％聚赖氨酸、0．5％甘氨酸、0．05％山梨酸钾、0．03％双乙酸钠、0％Nisin、0．003％EDTA。在玉米汁饮料中添加上述制剂,保鲜期可达到6d。     

玫瑰香葡萄贮藏环境气体阈值和极值的研究

研究了不同气体组合条件，玫瑰香葡萄0℃下120天的贮藏效果。结果表明，气调有利于玫瑰葡萄贮藏，合适的气体环境能够明显防止玫瑰香葡萄腐烂和脱粒，保持果梗的绿色，葡萄果实中的乙醇含量升高不明显。玫瑰香葡萄最佳气体成分为10％O2＋8％CO2，CO2伤害极值为10％O2＋18％CO2条件下100天，10％O2＋15CO2条件下120天；低O2伤害症状不明显。     

低温灌肠肉制品中复合防腐剂的研究

研究了在低温灌肠制品中添加几种防腐剂，来提高其保质期的方法，并通过单因素实验和正交实验的方法找出了最佳的防腐剂组合。结果表明，山梨酸钾、双乙酸钠、乳酸钠、乳酸链球菌素等4种防腐荆单独使用时在提高低温肉制品保质期方面的效果并不明显，如4种防腐剂复合后使用则效果最佳。最佳组合是：A3BQ岛，即乳酸链球菌素0．5g/kg，山梨酸钾0．6g/kg，双乙酸钠0．6g/kg，乳酸钠5．0g／kg，应用于低温灌肠肉制品中可使其常温下的保质期达三个多月，同时感官品质也较好。     

延长豆腐丝保质期的研究

选取山梨酸钾、脱氢醋酸钠、杀菌温度和杀菌时间作为影响豆腐丝保鲜效果的4个因素,通过正交试验选出A2B1C2D3(山梨酸钾1.5%,脱氢醋酸钠2%,杀菌温度110℃,杀菌时间10 min)为最佳工艺,有效的将豆腐丝的保质期延长到了30 d。     

乙醇和山梨酸钾对鲜食葡萄采后灰霉菌的抑制作用

灰葡萄孢接触10％和20％的乙醇30s后接种在PDA培养基上的萌发率分别是87％和56％，而对照是99％。用山梨酸钾进行同样处理，灰葡萄孢萌发率分别是84％和68％。用10％和20％乙醇加0．5％和1．0％山梨酸钾协同处理能显著提高对灰葡萄孢的抑制效果。20％乙醇和0．5％山梨酸钾处理后孢子萌发率是9．7％。接种灰葡萄孢的散粒“火焰无核”葡萄用水、10％和20％乙醇、0．5％和1．0％山梨酸钾单独处理后灰霉发生率分别为55．2％、42．1％、31．0％、37．7％和24、4％，而10％和20％乙醇加0．5％和1、0％山梨酸钾协同处理腐烂率都降到10％以下。接种灰葡萄孢的“汤姆森无核”葡萄串用10％和20％乙醇、0．5％和1．0％山梨酸钾单独及协同处理30s，在1℃下贮藏30d后发现20％乙醇加0．5％和1．0％山梨酸钾协同处理对灰葡萄孢的抑制效果与使用S0：药垫的效果相当，并且对葡萄无任何伤害。     

杏汁饮料的工艺配方及稳定性研究

以新鲜杏肉为主要原料设计了混浊型果汁饮料的加工工艺,采用正交实验设计方案,以感官风味作为评价指标,优选出杏汁、蔗糖和柠檬酸的最佳复配比为：14％杏汁＋8％蔗糖＋0．08％柠檬酸,并确定复合稳定剂的最佳组合为：0．10％果胶＋0．15％CMC＋0．10％黄原胶。     

杏计饮料的工艺配方及稳定性研究

以新鲜杏肉为主要原料设计了混浊型果汁饮料的加工工艺，采用正交实验设计方案，以感官风味作为评价指标，优选出杏汁、蔗糖和柠檬酸的最佳复配比为：14％杏汁＋8％蔗糖＋0．08％柠檬酸，并确定复合稳定剂的最佳组合为：0．10％果胶＋0．15％CMC＋0．10％黄原胶。     

红枣冰淇淋的研制

本文对影响红枣冰淇淋膨胀率主要因素进行了研究。通过试验确定了枣泥添加量、老化时间、复合乳化剂的最佳用量，即枣泥添加量为8％，在0-4℃下老化6～8h，复合乳化剂配比为0．10％海藻酸钠＋0.20％CMC＋0．05％单甘酯＋0.10％明胶，冰淇淋的口感、风味和膨胀率俱佳。     

Control of Listeria monocytogenes in ready-to-eat meats containing sodium levulinate, sodium lactate, or a combination of sodium lactate and sodium diacetate

ABSTRACT:  This study investigated the use of sodium levulinate to prevent outgrowth of Listeria monocytogenes in refrigerated ready-to-eat (RTE) meat products. Turkey breast roll and bologna were formulated to contain 1%, 2%, or 3% (w/w) sodium levulinate, 2% sodium lactate, a 2% combination of sodium lactate and sodium diacetate (1.875% sodium lactate and 0.125% sodium diacetate), or no antimicrobial (control). Samples of the RTE products were sliced, inoculated with 10² to 10³ CFU/cm² of a 5-strain cocktail of L. monocytogenes , vacuum packaged, and stored at refrigeration temperature for 0 to 12 wk. Counts reached 10⁸ CFU/cm² on control turkey roll product after 8 wk, and over 10⁷ CFU/cm² on control bologna after 12 wk. Addition of 2% or more sodium levulinate to turkey roll and 1% or more sodium levulinate to bologna completely prevented growth of L. monocytogenes during 12 wk of refrigerated storage. A consumer taste panel with pathogen-free samples found no differences in the overall liking among the preparations of turkey roll or among preparations of bologna. These results show that sodium levulinate is at least as effective at inhibiting outgrowth of L. monocytogenes in RTE meat products as the current industry standards of lactate or lactate and diacetate, and levulinate addition does not alter the overall liking of the RTE meat products.     

Effects of potassium lactate, sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks

This study determined the effects of potassium lactate (KL), sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks. Enhancement solutions (8.5% pump) contained combinations of KL (0% or 1.5%), sodium chloride (0.3% or 0.6%), sodium tripolyphosphate (0% or 0.3%), and sodium acetate (0% or 0.1%). Steaks were packaged in a high-oxygen modified atmosphere (80% O(2)/20% CO(2)). Steaks with KL or KL and sodium acetate were darker but more colour stable (P<0.05) than control steaks. Steaks had less glossy surfaces when they contained acetate (P<0.05) and KL (P<0.11). Increasing sodium chloride content resulted in darker, less colour-stable steaks (P<0.05). Removing phosphate had little impact on colour (P>0.05). Both KL and sodium acetate improved visual appearance of injection-enhanced beef rib steaks, whereas the greater salt level were detrimental.     

Effect of sodium phytate, sodium pyrophosphate and sodium tripolyphosphate on physico-chemical characteristics of restructured beef

The effects of 0.5% sodium phytate (SPT), sodium pyrophosphate (SPP), and sodium tripolyphosphate (STPP), along with 1% NaCl, on physico-chemical properties of restructured raw and cooked beef were evaluated. In raw beef stored for 1 day at 4 ° C, the SPT, SPP, and STPP increased pH and salt-soluble protein level and decreased %MetMb and thiobarbituric acid reactive substances (TBARS), compared to the control with salt alone (p < 0.05). In cooked beef, SPT, SPP, and STPP increased bind strength, cook yield, moisture level, and pH, and decreased TBARS (p < 0.05). SPP and STPP increased orthophosphate in both raw and cooked beef (p < 0.05), compared to the SPT and control. SPT, SPP, and STPP decreased the Hunter color L and b values and increased a value in raw beef (p < 0.05) but had no effect on the Hunter color values in cooked beef. The binding value of SPP and STPP were similar over time, and the time to reach maximum binding strength was 10s longer than SPT and 25s longer than the control. These results indicate that SPT compares favorably with traditional phosphates for bind strength and cooked yield, but SPT was slightly more effective than other phosphates for reduction of TBARS 1 day after cooking.     

Thyrotoxicity of sodium arsenate, sodium perchlorate, and their mixture in zebrafish Danio rerio

Both perchlorate and arsenate are environmental contaminants. Perchlorate is a definitive thyroid disruptor, and arsenic may disrupt thyroid homeostasis via multiple pathways. To evaluate the effects of sodium perchlorate and sodium arsenate on thyroid function and possible interactions between them, zebrafish (Danio rerio) were exposed to sodium perchlorate (10 and 100 mg/L), sodium arsenate (1 and 10 mg/L), and the mixture sodium perchlorate + sodium arsenate (10 + 1 and 100 + 10 mg/ L) for up to 90 days. At day 10, 30, 60, and 90, fish were sampled and analyzed forthyroid histopathological end points including follicular cell height, follicle size, colloid size, colloid depletion, hyperplasia, and angiogenesis. Effects on epithelial cell height (hypertrophy) were seen as early as 10 days after exposure. Perchlorate induced changes in all parameters staring at 30 days of exposure. Prolonged perchlorate exposure induced angiogenesis, a relatively new marker of thyroid disruption. Sodium arsenate was less effective than sodium perchlorate in causing thyroid histopathologies, but transient responses were seen for hypertrophy, hyperplasia, and colloid depletion (% colloid). This is the first report of arsenate-induced effects on thyroid histopathology. However, because statistically significant effects were not consistently seen in all end points, evidence for arsenate as a thyroid disruptor remains equivocal. In general, the sensitivity of the following histopathological indicators for indicating thyroid perturbations is, in descending order: follicular cell height > percent of colloid area/follicle area > colloid area/follicular cell height > hyperplasia > angiogenesis > colloid area >follicle area = fish growth.     

Injection of sodium chloride, sodium tripolyphosphate, and sodium lactate improves Warner-Bratzler shear and sensory characteristics of pre-cooked inside round roasts

Paired inside rounds (n=30 pairs) were removed from randomly selected USDA Select quality grade carcasses to examine the effects of injecting a solution of sodium lactate, sodium tripolyphosphate, and sodium chloride on Warner-Bratzler shear force, cooking loss, lipid oxidation, and sensory characteristics of pre-cooked beef. Injected treatments were more tender (P<0.05) than control products, as measured by Warner-Bratzler shear force and consumer sensory panel ratings. Injected treatments had lower (P<0.01) cooking and re-heating loss percentages when compared to control samples. Lipid oxidation in injected treated samples was significantly reduced as compared to control meat samples. Results of lipid oxidation also revealed that 14-day samples were less (P<0.01) than 0-day samples. Results of this experiment have shown that injection of this solution enhanced sensory panel characteristics, and decreased WBS values and cooking loss.     

The ensiling capability of a mixture of sodium benzoate, potassium sorbate, and sodium nitrite

The objective of this study was to evaluate the effects of an additive comprising sodium benzoate, potassium sorbate, and sodium nitrite on the quality of silages fermented from various forage crops. Thirteen crops in 3 groups (differing in dry matter concentration and degree of ensilability) were treated with the additive mixture and compared with untreated control silages. The main focus was on yeast and Clostridia spp. activity in the silages, although other silage quality criteria also were measured. Treated silages from difficult-to-ensile crops at low dry matter were found to have significantly lower silage pH, fewer clostridial spores, and reduced concentrations of ammonia N, butyric acid, and ethanol. In addition, dry matter losses were reduced in treated silages compared with those receiving no additive. Similar results were observed in silages from easy or intermediate ensilable crops when the dry matter concentration was <300 g/kg. When the dry matter concentration was >350 g/kg, the treated silages contained less ammonia N, ethanol, and yeast for 3 out of 4 forages. All treated silages from all crops were aerobically stable during the examination time. The application of the tested additive mixture reduced the growth of undesirable microflora and thereby reduced silage losses and prolonged the aerobic stability of the silages.     

Protein variations in Listeria monocytogenes exposed to sodium lactate, sodium diacetate, and their combination

Most studies of the effect of adverse conditions on survival of Listeria monocytogenes have focused on stress caused by acid or sodium chloride. However, no information is available on resistance of this pathogen to stress caused by salts of organic acids. Sodium lactate and sodium diacetate are generally recognized as safe substances and are approved as ingredients for use in foods. We evaluated antilisterial properties of each of these salts and the enhanced inhibition effected by their combination in ready-to-eat meat products at pH 6.3. Changes in proteins found in this pathogen were studied in the presence of the salts in a chemically defined medium at the same pH using a proteomic approach. The total numbers of protein spots obtained from two-dimensional electrophoresis were 198, 150, and 131 for sodium diacetate, sodium lactate, and the control, respectively. Sodium diacetate treatment produced the highest number of unmatched proteins (124 versus 53 in lactate), the greatest increase in expression (20 versus 5 in lactate), and the highest number of novel proteins (90 versus 45 in lactate). The number of repressed proteins was highest in the combination treatment (41 versus -30 in the single salt treatment). Six proteins that increased or decreased by > or = 10-fold were further investigated; oxidoreductase and lipoprotein were upregulated, and DNA-binding protein, alpha amylase, and two SecA proteins were downregulated or completely suppressed by the salt treatment. Identification of all protein spots is essential for comparison with proteins induced or suppressed under other stress conditions.     

Structure and composition of model cheeses influence sodium NMR mobility,kinetics of sodium release and sodium partition coefficients

The mobility and release of sodium ions were assessed in model cheeses with three different lipid/protein ratios, with or without added NaCl. The rheological properties of the cheeses were analysed using uniaxial compression tests. Microstructure was characterised by confocal laser scanning microscopy. ²³Na nuclear magnetic resonance (NMR) spectroscopy was used to study the molecular mobility of sodium ions in model cheeses through measurements of the relaxation and creation times. Greater mobility was observed in cheeses containing a lower protein content and with added NaCl. The kinetics of sodium release from the cheese to an aqueous phase was correlated with the mobility of sodium ions. The highest rates of sodium release were observed with a lower protein content and with added NaCl. The water/cheese partition coefficients of sodium increased when NaCl was added or the protein content was higher. The study highlighted the effect of model cheese characteristics on molecular and macroscopic behaviours of sodium.     

Quality and hygiene of beef burgers in relation to the addition of sodium ascorbate,sodium citrate and sodium acetate

We evaluated the effects of two additive mixtures (sodium ascorbate 1 g kg^?1, sodium citrate 1 g kg^?1 and sodium acetate 1.75 or 2.5 g kg^?1) on the microbiological and physical–chemical characteristics of non‐prepacked beef burgers stored in air at 4 °C or 12 °C for 96 h. Total microbial count reached 7 Log CFU g^?1 48 h later in treated samples at 4 °C. The mixture containing the higher acetate concentration led to a smaller increase in Gram‐negatives, in particular Pseudomonas (2 Log of difference towards control samples at 96 h); at 12 °C, a 1.7 Log difference in Enterobacteriaceae was also shown. Total viable basic nitrogen was significantly lower in the treated samples at 12 °C. The addition resulted in pH stabilisation and lower cooking loss and positively influenced the a* index of burgers at 4 °C. Clearly, the use of these mixtures should not be a substitute of good hygienic practices and optimal storage conditions.