盐腌肉制品复合腌制剂配方筛选的研究

本试验首先对鲜肉中的微生物进行了初步分离;然后征对分离出的细菌采用抑菌圈试验法研究了复合腌制剂不同配比对肠杆菌科菌和热死环丝菌的抑制效果;最后进行腌肉试验,证实了当乳酸钠2%,柠檬酸2%,抗坏血酸0.2%,乙酸1.2%,氯化钠3.5%时,能够较好的抑制细菌的生长,为生产低盐腌肉制品提供了理论依据。     

正交试验法优化板栗蓉分级护色工艺

为抑制板栗在制蓉过程的褐变,对其加工过程采用二级护色工艺。通过测定样品的总色差(△E*),分别研究了柠檬酸、抗坏血酸、L-半胱氨酸和氯化钠对板栗色泽的影响,进行单因素和正交试验,确定最佳的护色液配方。结果表明,柠檬酸、抗坏血酸、L-半胱氨酸和氯化钠在板栗制蓉过程中均有抑制褐变的效果。一级护色的最佳配方为:柠檬酸0.05%,抗坏血酸0.75%,L-半胱氨酸0.17%,氯化钠2.00%;二级护色的最佳配方为:柠檬酸0.45%,抗坏血酸0.65%,L-半胱氨酸0.05%,氯化钠1.90%。     

不同生物保鲜剂对冷藏南美白对虾的保鲜效果

为提高冷藏南美白对虾的贮藏品质,分别采用0.05%溶菌酶、0.1%植酸、0.5%柠檬酸、0.15%抗坏血酸、0.5%L-半胱氨酸和1.5%壳聚糖保鲜对虾,通过感官评价、pH、细菌总数、挥发性盐基氮和多酚氧化酶相对酶活力的测定评价保鲜效果。研究结果表明,1.5%壳聚糖能有效减缓新鲜对虾感官品质的下降,并抑制微生物生长,0.5%柠檬酸对挥发性盐基氮抑制效果最好,并有较强的抑制多酚氧化酶作用,0.5%L-半胱氨酸能有效抑制多酚氧化酶和黑变,而0.05%溶菌酶、0.1%植酸和0.15%抗坏血酸对南美白对虾的品质改善不明显。     

不同抑制剂对澳洲青苹中多酚氧化酶活性的影响

以澳洲青苹为试验材料,邻苯二酚为底物,在波长420nm下,采用分光光度法测定澳洲青苹中多酚氧化酶的活力。本文分别研究了亚硫酸氢钠、抗坏血酸、柠檬酸对澳洲青苹多酚氧化酶(PPO)活性的影响,并通过正交试验筛选出最佳复合抑制剂组合。试验结果表明:添加量为50mg/kg的亚硫酸氢钠、125mg/kg的抗坏血酸浓度为、600mg/kg的柠檬酸均能有效抑制PPO活性,三种抑制剂中亚硫酸氢钠对澳洲青苹中PPO活性抑制效果最好,最高抑制率为78.58%。复合抑制剂对澳洲青苹中PPO抑制效果明显,最佳复合抑制剂组合为亚硫酸氢钠25mg/kg、抗坏血酸125mg/kg、柠檬酸600mg/kg,抑制率能达90.09%。     

紫薯酒褐变抑制研究

目的抑制紫薯酒的褐变,提高果酒的品质。方法以紫薯1号为原料,研究紫薯酒加工过程中褐变抑制剂对果酒褐变的抑制效果。在单因素试验的基础上,通过L_9(3~4)正交试验优化抗坏血酸、柠檬酸、蜂蜜和壳聚糖的最佳添加量。结果影响紫薯酒褐变度的因素依次为:柠檬酸添加量(B)壳聚糖添加量(D)抗坏血酸添加量(A)蜂蜜添加量(C),最佳褐变抑制剂条件为抗坏血酸添加量0.8%,柠檬酸添加量0.5%,蜂蜜添加量12%,壳聚糖添加量0.06%。结论发酵前添加一定剂量的褐变抑制剂有利于抑制紫薯酒的褐变现象。     

橄榄提取液对猪油自氧化的抑制能力的研究

实验采用Na2S2O3-I2滴定法测定橄榄提取液对猪油自氧化的抑制能力,同时研究了橄榄提取液与抗坏血酸和柠檬酸的协同抗氧化作用。结果表明：不同浓度的橄榄提取液对猪油自氧化均能表现出抑制作用,其中1%橄榄提取液的抑制能力最好;在相同条件下,橄榄提取液、抗坏血酸和柠檬酸三者中抗坏血酸对猪油自氧化的抑制能力最强,其次是橄榄提取液,抑制能力最弱的为柠檬酸;橄榄提取液分别与抗坏血酸和柠檬酸协同使用时均能提高橄榄提取液对猪油自氧化的抑制能力,但与柠檬酸的协同效果明显强于与抗坏血酸的协同效果。     

乙醇及有机酸对木醋杆菌合成细菌纤维素的影响

研究了乙醇、草酸、酒石酸、丙酮酸、苹果酸、乳酸、乙酸、柠檬酸、丁二酸对木醋杆菌产细菌纤维素的影响。结果发现:丙酮酸、乳酸、乙酸、乙醇、苹果酸、柠檬酸、丁二酸对木醋杆菌合成细菌纤维素有促进作用;草酸、酒石酸对木醋杆菌合成细菌纤维素有抑制作用;乙醇及各有机酸的最佳添加浓度分别为:丙酮酸0.15%,苹果酸0.1%,乳酸0.3%,乙酸0.4%,柠檬酸0.1%,丁二酸0.2%,乙醇4%;由正交实验得混酸的最适添加配比为:丙酮酸0.1%,苹果酸0.12%,乳酸0.2%,乙酸0.3%,柠檬酸0.12%,丁二酸0.2%,乙醇3%,BC产量达3.012g/L,是空白实验组的2.03倍。     

有机酸浸渍处理对苹果片冻干品质的影响

采用浓度为1%,2%,3%,4%的柠檬酸、乙酸、苹果酸和抗坏血酸浸渍苹果片,以冻干苹果片色泽、产出率、复水比、形变率、质地特性及微观结构为检测指标,分析不同酸浸渍对真空冷冻干燥苹果片品质的影响。结果表明:柠檬酸、抗坏血酸和苹果酸处理冻干苹果片的总色差值△E随酸浓度的增加而增加,乙酸处理冻干苹果片△E值相对较小,护色效果好;经柠檬酸、抗坏血酸、苹果酸处理冻干苹果片形变率随浓度的增加有增加的趋势,且显著高于乙酸处理组和未浸渍组(P0.05),而乙酸处理组的形变率较未浸渍组略有降低;酸浸渍处理冻干苹果片的复水比均显著高于未浸渍组(P0.05)。在浓度为1%的条件下,苹果酸和乙酸较其他酸处理冻干苹果片后的组织细胞较为完整,细胞壁较厚,表现出较高的硬度和较小的形变率。因此乙酸可以较好地保持冻干苹果片的综合品质。     

压差膨化苹果脆片的无硫护色研究

针对压差膨化前处理中苹果的酶促褐变进行了无硫护色研究,通过单因素试验、正交试验研究了不同护色剂及其组合对苹果片的护色效果的影响。试验结果表明柠檬酸、氯化钠、抗坏血酸对苹果片护色效果影响较显著,试验中最佳的复配护色剂组合为:柠檬酸0.4%、抗坏血酸0.04%、氯化钠1.0%;护色温度是25℃,时间20 min,使用该方法护色的苹果片能很好抑制膨化前的酶促褐变。     

杏汁的护色工艺研究

采用单因素试验和正交试验方法,优化和评价氯化钠、柠檬酸、抗坏血酸、亚硫酸氢钠对杏汁色泽的影响.试验结果表明:添加量应适当,过大反而会使杏汁感官品质降低;氯化钠、柠檬酸、抗坏血酸、亚硫酸氢钠对杏汁都有一定的护色效果;杏汁护色的最佳配方为:2%的氯化钠、0.15%的柠檬酸、0.03%的抗坏血酸、0.08%的亚硫酸氢钠.     

Survival of Escherichia coli O157:H7 in meat product brines containing antimicrobials

Brine solution injection of beef contaminated with Escherichia coli O157:H7 on its surface may lead to internalization of pathogen cells and/or cross-contamination of the brine, which when recirculated, may serve as a source of new product contamination. This study evaluated survival of E. coli O157:H7 in brines formulated without or with antimicrobials. The brines were formulated in sterile distilled water (simulating the composition of freshly prepared brines) or in a nonsterile 3% meat homogenate (simulating the composition of recirculating brines) at concentrations used to moisture-enhance meat to 110% of initial weight, as follows: sodium chloride (NaCl, 5.5%) + sodium tripolyphosphate (STP, 2.75%), NaCl + sodium pyrophosphate (2.75%), or NaCl + STP combined with potassium lactate (PL, 22%), sodium diacetate (SD, 1.65%), PL + SD, lactic acid (3.3%), acetic acid (3.3%), citric acid (3.3%), nisin (0.0165%) + ethylenediamine tetraacetic acid (EDTA, 200 mM), pediocin (11000 AU/mL) + EDTA, sodium metasilicate (2.2%), cetylpyridinium chloride (CPC, 5.5%), or hops beta acids (0.0055%). The brines were inoculated (3 to 4 log CFU/mL) with rifampicin-resistant E. coli O157:H7 (8-strain composite) and stored at 4 or 15 °C (24 to 48 h). Immediate (0 h) pathogen reductions (P < 0.05) of 1.8 to ≥ 2.4 log CFU/mL were observed in brines containing CPC or sodium metasilicate. Furthermore, brines formulated with lactic acid, acetic acid, citric acid, nisin + EDTA, pediocin + EDTA, CPC, sodium metasilicate, or hops beta acids had reductions (P < 0.05) in pathogen levels during storage; however, the extent of pathogen reduction (0.4 to > 2.4 log CFU/mL) depended on the antimicrobial, brine type, and storage temperature and time. These data should be useful in development or improvement of brine formulations for control of E. coli O157:H7 in moisture-enhanced meat products. PRACTICAL APPLICATION: Results of this study should be useful to the meat industry for developing or modifying brine formulations to reduce the risk of E. coli O157:H7 in moisture-enhanced meat products.     

Microbiological, Chemical, and Physical Changes in Fresh, Vacuum-Packaged Pork Treated with Organic Acids and Salts

The effects of selected organic acids and salts on microbial numbers, pH, exudate, and color were studied for vacuum-packaged, fresh pork chops. Pork chops were dipped for 2 min in (v/v) 1% acetic acid, 1% acetic/1% lactic acid, 1.5% acetic/1.5% sodium acetate, 3% acetic/3% sodium ascorbate, 3% acetic/2% NaCl or sterile, distilled water before being vacuum-packaged and stored at 2°– 4°C for 6 weeks. Treatments containing 3% acetic acid resulted in lower aerobic microbial numbers (P < 0.05) and effectively inhibited Enterobacteriaceae. Treatments containing 1% acetic acid, with or without 1% lactic acid, were ineffective. All acid treatments increased exudate and were detrimental to meat color (P < 0.05) although sodium ascorbate reduced color damage. Chops treated with 3% acetic acid/3% sodium ascorbate had the highest Hunter a and L color scores.     

复合保鲜剂对冷鲜肉货架期的影响

采用复合保鲜剂1%醋酸+3%柠檬酸+0.1%抗坏血酸和1%醋酸+1%乳酸+0.2%茶多酚对冷却肉进行处理,分别在0、3、6、9天测定样品的菌落总数、大肠菌群和挥发性盐基氮,并对样品的颜色和感官性状进行评价。结果表明:复合保鲜剂1%醋酸溶液+1%乳酸+0.2%茶多酚可使鲜肉在第6天时,菌落总数、大肠菌群、挥发性盐基氮在鲜肉要求范围之内,并且感官状态良好,该复合试剂能够达到延长冷鲜肉货架期的目的。     

EFFICACIES OF ACETIC, LACTIC AND TWO MIXED ACIDS IN REDUCING NUMBER OF BACTERIA ON SURFACE OF LEARN MEAT

This study on sanitizing beef surfaces was designed to evaluate effects of mixtures of acetic, lactic, citric and ascorbic acids with individual solutions of acetic and lactic acids. Acetic acid (3%), lactic acid (3%), MA1 (2% acetic, 1% lactic, 0.25% citric and 0.1% L-ascorbic acids) and MA2 (2% lactic, 1% acetic, 0.25% citric and 0.1% L-ascorbic acids) solutions were applied to beef core samples of muscle inoculated with bacteria. Experimental variables were type, concentration and temperature of acid solutions and type of microorganisms. Overall, an increase in either acid concentration or treatment temperature decreased numbers of residual viable bacteria. Lactic acid solution was the most effective against S. typhimurium with a reduction of 2 log₁₀ at 70°C. For enterobacteria, acetic, lactic and MA2 solutions at 70°C resulted in a 1.5 log₁₀ reduction. MA2 was the most effective acid solution at both 45 and 70°C, whereas, lactic acid and the MA2 mixture did not differ in effectiveness at 20°C.     

Microbiological and physicochemical changes of naturally black olives fermented at different temperatures and NaCl levels in the brines

The effect of different temperatures (25°C, 18°C and ambient temperature) and NaCl levels in brines (4%, 6% and 8%) on the microbiological and physicochemical characteristics of naturally black olives of Conservolea variety was studied for up to 190 days. Fermentation was carried out according to the traditional anaerobic method. The initial microflora consisted of Gram-negative bacteria, lactic acid bacteria and yeasts. Inhibition of Gram-negative bacteria was evident in all fermentations. The prevailing micro-organisms were lactic acid bacteria and yeasts, the association of which was dependent on the conditions of fermentation. At 25°C and 18°C in brines containing 4% and 6% NaCl, the growth of lactic acid bacteria was favoured resulting in a lactic acid fermentation, as indicated by the high free acidity levels and low pH values in the brines. On the contrary, 8% NaCl concentration affected the growth of lactic acid bacteria and enhanced the activity of fermentative yeasts, producing a final product with lower free acidity and higher pH value. At ambient temperature, the counts of lactic acid bacteria followed the fluctuation of temperature regardless of salt concentration, while yeasts did not seem to be affected. The lactic acid bacteria identified belonged to the species Lactobacillus mesenteroides, Lactobacillus brevis, Lactobacillus plantarum and Lactobacillus pentosus. The best conditions for fermentation were at 25°C and 6% NaCl, developing free acidity of 142 mM (1·28% w/v) lactic acid and pH value of 3·8. After 5 months of brining, olives fermented at 25°C were judged by panelists as being debittered and ready to eat. No off-odour development was detected in any case due to anomalous fermentation. The HPLC analysis revealed that citric, malic, tartaric, succinic, lactic and acetic were among the end products of fermentation.     

Effect of Partial Substitution of NaCl with KCl on Halloumi Cheese during Storage: Chemical Composition,Lactic Bacterial Count,and Organic Acids Production

Abstract: The effect of partial substitution of NaCl with KCl on chemical composition, lactic bacterial count, and organic acids profile of Halloumi cheese was investigated. Halloumi cheeses were made and kept in 4 different brine solutions at 18% including NaCl only (HA), 3NaCl : 1KCl (HB), 1NaCl : 1KCl (HC), and 1NaCl : 3KCl (HD) and then stored at 4 °C for 56 d. No significant effect was observed between control and experimental cheeses in terms of moisture, fat, protein, lactic bacterial count, and pH values at the same storage period. There was a significant difference in ash, sodium, and potassium contents among experimental cheeses at the same storage period. Ash, sodium, and potassium contents increased significantly during storage at same salt treatment. There was no significant difference in lactic and citric acid contents among experimental cheeses and that of the control. In contrary, there was a significant difference in acetic acid among experimental cheeses. A strong positive correlation was observed between ash, Na, and K contents. An inverse correlation between organic acids and both Na and K contents was also observed.     

Microbial evolution during storage of seasoned olives prepared with organic acids with potassium sorbate, sodium benzoate, and ozone used as preservatives

The effect of potassium sorbate, sodium benzoate, and ozone in combination with citric, lactic, and acetic acids on the microbial population of seasoned table olives of the olive 'Alore?a' cultivar was studied in both fresh (FF) and stored fruits (SF). The inactivation/growth curves were modeled and the biological parameters estimated, with yeast used as the target microorganism. Regardless of the acid added, potassium sorbate showed a general inactivation effect on yeasts in the products prepared from both FF and SE Sodium benzoate had a rapid inactivation effect with FF, but with SF, it was effective only in the presence of acetic acid. A strain of Issatchenkia occidentalis was found that was resistant to the combination of this preservative with citric or lactic acids. In FF, ozone showed an initial marked inhibition against yeasts, but later, yeasts were again able to grow. In SF, ozone was a strong inactivating agent when it replaced any of the traditional preservatives. Lactic acid bacteria were always absent in products prepared from FF, and apparently were not affected by the different preservative agents in those prepared from SF. The behavior of yeasts and lactic acid bacteria populations in commercial products were similar to those found in experimental treatments.     

Reducing Microbial Populations on Beef Tissues: Concentration and Temperature of an Acid Mixture

A mixture of 2% acetic, 1% lactic, 0.25% citric and 0.1% ascorbic acid was applied to beef core samples of muscle inoculated with bacteria. Experimental variables were concentration and temperature of mixed acids and type of microorganism. Overall, an increase in either mixed acids concentration (0 to 3%) or temperature (20 to 70°C) resulted in reductions in counts of about one logi₀ for aerobic bacteria and S. ryphimurium, less than one log₁₀ for Enterobacteriaceae, and about one-half log₁₀ for E. coli. Initial meat surface pH dropped to 4.3 after treatment with 3% mixed acids solution but rose to 5.2 after 24 hr. Overall, this mixture of acids performed about the same as acetic acid or lactic acid under the same conditions.     

Preservative effect of combinations of acetic acid with lactic or propionic acid on buffalo meat stored at refrigeration temperature

A silverside of buffalo was cut in 15 equal-sized steaks and divided into five groups, each group containing three steaks. The steaks from groups 1,2,3 and 4 were treated with 1, 2, 3 and 4% acetic:lactic acid combinations, respectively, and the fifth group was kept as a control. Similar treatments were also given with acetic: propionic acid mixtures. The microbial analysis and changes in colour and odour were noted at 0, 24, 72 and 168 h. The bacteriostatic and bacteriocidal action of the acid mixtures increased with increasing concentration but the effect was reduced as the time advanced. Both acid mixtures had pronounced antibacterial effect on gram negative organisms than gram positive ones. The 3% acetic: lactic acid combination showed reduction in bacterial numbers without affecting the colour and odour of buffalo meat and is recommended for decontamination and preservation of meat for up to seven days at refrigeration temperature (7 ± 1°C).