对面包中微生物生长变化及其抑制方法的探讨

面包在贮存过程中容易霉变,因此延长面包的保质期是面包工业一直研究的热点。该文研究了面包在贮存过程中皮层和瓤部微生物的生长变化,并提出防腐剂添加方法,对比了三种添加方法对面包防腐效果的影响。实验结果表明,面包在贮存过程中,皮层微生物繁殖速度高于瓤部,在表皮最先出现霉斑。采用丙酸钙混合添加、包裹添加和涂抹添加三种方式,都可以抑制微生物的繁殖速度,延长面包的保质期,防霉变的效果顺序为表皮涂抹>表皮包裹>混合添加。丙酸钙在面包表皮浓度越高,防霉变效果越好,加强面包皮层防腐对面包保鲜更加重要。     

对面包防腐剂添加方法的探讨

以丙酸钙为防腐剂代表,研究了丙酸钙混合添加、包裹添加和涂抹添加三种方式对面包防霉变效果的影响。实验结果表明,在丙酸钙混合添加、包裹添加和涂抹添加三种方式中,对面包防霉变效果影响的大小顺序为表皮涂抹、表皮包裹、混合添加。丙酸钙在面包表皮浓度越高,防霉变效果越好。     

食品防腐剂复配形式在面包中的防腐应用研究

食品防腐剂可防止微生物引起的食品腐败变质,有效延长面包的保质期和销售货架期,而各种防腐剂都有各自的作用范围,两种及以上的防腐剂合理复配使用,往往具有协同作用,比单独使用更为有效。我国《食品添加剂使用卫生标准》GB2760-2007中规定:面包中允许使用的防腐剂有三种:丙酸盐类、脱氢乙酸及其钠盐、山梨酸及其钾盐。本文选用丙酸钙、脱氢醋酸钠和山梨酸钾三种防腐剂,研究了丙酸钙与脱氢醋酸钠两者复配形式、丙酸钙与脱氢醋酸钠和山梨酸钾三者复配形式对面包的防腐效果。防腐剂复配添加量按各自用量占食品添加剂使用卫生标准规定的其最大使用量的比例之和等于1来确定,在面包制作工艺的主面团配料环节加入。结果表明,丙酸钙与脱氢醋酸钠两者复配形式更有利于延长面包保质期,复配的比例6:4。     

馒头中微生物变化及其抑制方法研究

研究了馒头在贮存过程中不同部位微生物的生长变化,对比了3种防腐剂添加方法对馒头的防腐效果。结果表明:馒头在贮存过程中,皮层微生物繁殖速度高于瓤部。采用丙酸钙混合添加、包裹添加和涂抹添加3种方法,均可以抑制微生物的繁殖速度,延长馒头的保质期。对防霉变效果的顺序依次为表皮涂抹表皮包裹混合添加。丙酸钙在馒头表皮浓度越高,防霉变效果越好。     

面包防腐剂对酵母发酵力的影响研究

面包防腐剂丙酸钙、山梨酸钾、脱氢乙酸钠及其复合防腐剂对面包防腐效果明显,被广泛应用到面包工业中。采用浮水法研究单一和复合面包防腐剂对酵母发酵力的影响。研究结果发现,面包防腐剂对酵母的发酵力有不同程度的抑制作用,防腐剂添加量越大,抑制作用越大,部分复合防腐剂对酵母的发酵力抑制作用也比单一防腐剂大。由于防腐剂影响酵母发酵力和面团的发酵体积,对面包的烘焙品质有很大的副作用,在面包工业中,在保证防腐剂对面包防腐效果的同时,应适量添加防腐剂,以降低防腐剂对酵母发酵力的影响,提高面包烘焙品质。     

食品添加剂丙酸钙的生产工艺优化研究

丙酸钙在市场中属于一种新型的饲料防腐剂和食品防腐剂,对好气性芽孢杆菌、霉菌好革兰氏阴性菌都有着十分显著的杀灭效果,甚至还可以对黄曲霉素的产生进行有效抑制。丙酸钙不但可以让饲料和食品的保鲜期得以有效延长,同时还可以通过代谢被人、畜吸收,为机体提供日常所需的钙,被广泛应用在蛋糕和面包等食品和相关复配饲料的防腐中。     

乳化剂改进广式月饼回软回油性能的研究

对用于改善广式月饼回软回油性能的复合乳化剂进行了研究,通过正交试验确定了调制广式月饼饼皮所用复合乳化剂的配比及用量,添加该乳化剂的月饼能迅速回软、回油;并通过添加丙酸钙作为防腐剂有效抑制了细菌和霉菌的生长。     

栅栏技术在面包防腐中的应用

应用栅栏技术,对面包的水分活度(甘油和山梨糖醇)、复配防腐剂(脱氢乙酸钠与丙酸钙复配)和复合充气包装(二氧化碳与氮气复配)3个栅栏因子进行研究,以贮存时间和感官评分为指标,确定面包保存的最佳栅栏条件。通过正交实验,得到最佳栅栏条件:水分活度(甘油2%、山梨糖醇4%)、脱氢乙酸钠与丙酸钙复配比例2∶3、二氧化碳与氮气的充气比例1∶2。通过试验验证,在此条件下,面包贮存时间最长为61天。     

链霉菌HMJ-7和SC-4抗菌物质应用研究

通过打孔法确定了链霉菌HMJ-7和SC-4 2种菌株的发酵液对大肠杆菌、蜡样杆菌、藤黄微球菌等细菌和黑曲霉等霉菌都具有良好的抑制作用。通过向馒头、面包、香蕉、草莓、西瓜汁中添加不同浓度的抗菌物质稀释液,确定了HMJ-7和SC-4所产抗菌物质在馒头、面包、香蕉、草莓、西瓜汁的贮存过程中起到的良好的防腐效果。研究结果对抗菌物质在食品防腐中的进一步应用具有重大的意义。     

脱氢醋酸钠及其复配形式在食品中的防腐应用研究

脱氢醋酸钠是一种广谱性抑菌力极强的食品防腐剂,对霉菌、细菌、酵母的抑制能力尤强.本文系统地研究了脱氢醋酸钠及其复配形式在面制品、肉制品、豆制品中的防腐应用,结果表明单一防腐剂处理,脱氢醋酸钠的抑菌能力优于山梨酸钾、双乙酸钠、丙酸钙;复配形式以脱氢醋酸钠与月桂酸单甘油酯为主体,配以山梨酸钾或丙酸钙、双乙酸钠,其防腐效果较单一防腐剂效果好.     

Synergistic effect of chemical preservatives with ethanol on the microbial shelf life of bread by factorial design

The shelf life, particularly the mould-free shelf life (MFSL) of bread, was evaluated either by adding a conventional chemical preservative or by spraying the surface of bread, in which a chemical preservative was added. As bread making is a complex process and bread is a multicomponent system, the investigation was based on statistical design experiments. Using first-order factorial designs, reliable models were constructed, revealing the effects of some common ingredients of bread (such as salt, sugar, glycerol, potassium sorbate, calcium propionate) and their interactions on the MFSL (optimisation parameter) with and without ethanol surface spraying. The effectiveness of preservation was ranked as potassium sorbate + ethanol > calcium propionate + ethanol > potassium sorbate > calcium propionate. Ethanol addition led to MFSL prolongation of 43.5% and 38.5% compared with MFSL of potassium sorbate and calcium propionate, respectively, when all the factors were fixed to their basic levels.     

INCIDENCE OF MESOPfflLIC ANAEROBIC BACTERIA AND LACTIC ACID BACTERIA ON SLICED BREAD UNDER MODIFIED ATMOSPHERE PACKAGING DURING STORAGE

A total of 192 samples of sliced bread of different composition, water content and pH were selected to test the efficiency of modified atmospheres packing (MAP) on total mesophilic anaerobic bacteria and lactic acid bacteria (LAB) counts during MAB storage. The addition of calcium propionate and the storage temperature influenced significantly the counts. During most of the storage period at 15–20C, the concentration of O₂ was very low and that of CO₂ was constant or increased according to the atmosphere used. LAB counts increased in a significant way in the first week under CO₂ atmospheres. For the sliced bread, the highest counts were obtained under CO₂ atmospheres. In general, we consider that the presence/absence of calcium propionate added had a greater influence than the MAP conditions.     

复配型食品抗菌改良剂对馒头保质保鲜的影响

在馒头的配方中添加脱氢乙酸钠、丙酸钙、抗坏血酸3种食品抗菌改良剂,采用一次发酵工艺,对所生产馒头的保质时间、口感、外观以及风味进行评定,研究抗菌添加剂对馒头保质保鲜的影响及最优抑菌配方。结果表明:添加脱氢乙酸钠0.015%(质量分数)、丙酸钙0.1%(质量分数)、抗坏血酸0.18%(质量分数)时,馒头的品质及抑菌的效果为最好。     

西藏开菲尔发酵提取物对牛奶和馒头防腐作用的研究

将西藏开菲尔发酵物FXJX按照一定添加量分别加入到牛奶和馒头中,在不同时间测定它们的微生物指标和理化指标,并对感官情况进行评定。同时以乳酸,乳酸链球菌素和丙酸钙作为阳性对照组。结果表明:添加了FXJX后的牛奶和馒头,在储藏过程中微生物的数量比其它阳性对照组的要少,大肠杆菌数呈阴性;在牛奶中的酸度到第10 d才超出国家标准要求;还有对牛奶和馒头的感官起到更好的保护和延缓恶化的作用,这些都表明FXJX对这两种食品有很好的防腐效果。     

牡蛎壳丙酸钙的非煅烧法制备工艺及其抑菌活性研究

以牡蛎壳为钙源,不经过高温煅烧,经粉碎、水飞法处理后直接用于制备丙酸钙。为了获得最佳工艺条件,考察了反应温度、丙酸量、反应时间等因素对产率的影响。结果表明,在60℃、丙酸过量75%条件下转化反应进行2h,丙酸钙产率可达87.9%,且产品纯度大于99.5%。同时,研究还发现丙酸钙对大肠杆菌、志贺氏菌和荧光假单胞菌三种革兰氏阴性菌均有一定的抑制效果,并具有显著延缓面包片霉变的效果。     

Microbiological Characteristics of Part-Baked White Pan Bread During Storage

In this study, white pan breads part-baked 10, 15, and 20 min with and without added calcium propionate were stored at 20°C (room temperature) for 3, 5, and 7 days and at 4°C (refrigerator temperature) for 7, 14, and 21 days. After storage, the baking time of part-baked breads was completed to the baking time of control breads (25 min). Total aerobic mesophylic bacteria (TAMB), coliform bacteria, yeast and mold, and Bacillus spore counts of breads were determined before and after the second baking. While TAMB, yeast and mold counts were 8-log CFU/g in dough, it was measured as 6 and 2-log CFU/g before and after the rebaking process, respectively. Microorganism counts of the part-baked breads without Ca-propionate stored at room temperature increased in significant amounts. However, the second baking process after storage contributed to the re-freshness of breads and decreased the microorganism counts. The levels of water activity (a_w) for breads with and without ca-propionate stored at different temperatures and time profiles approximately ranged from 0.92 to 0.89 after the rebaking process and did not significantly affect the microorganism counts. However, addition of calcium propionate in the bread formulation significantly decreased TAMB, coliform bacteria, Bacillus spore, and yeast and mold counts, depending on decrease of pH levels. It was found that the microbiological quality of the rebaking bread with Ca-propionate after part-baking for 10 and 15 mins and storage at both room and refrigerator temperature was much higher than that of the other.     

响应面法优化馒头的抑菌配方

微生物(主要是腐败菌)的生长繁殖是引起馒头腐败变质的主要原因,控制馒头的水分活度、pH值和添加防腐剂有利于抑制细菌。利用响应曲面设计,以木糖醇、丙酸钙、柠檬酸为因素,细菌生长对数为响应值建立响应曲面模型,以确定最佳的馒头抑菌配方。优化结果表明:在木糖醇3.252%(质量分数),丙酸钙0.134%(质量分数),柠檬酸0.234%(质量分数)时,培养48h后,馒头中的细菌生长对数为2.591,抑制细菌的效果最佳,且该配方下的实验结果与模型拟合程度较好。     

Multiparametric investigation of mould‐free shelf life of bread via factorial design

The investigation of a complex process, such as the bread making process, can be greatly favored by the approach of statistical design of experiments. Using simple first order factorial designs, reliable models were constructed investigating the effects of salt, sugar, sorbic acid, calcium propionate, vegetable fibers, fat and emulsifier on the shelf life of bread (optimization parameter). These effects were in general linear. An exception was observed in the case of use of calcium propionate where an interaction between salt and sugar was determined. The effects of all significant factors on optimization parameter were reasonable. Sorbic acid and calcium propionate proved to be more effective preservatives than salt and sugar by an order of magnitude. Antifungal efficiency of sorbic acid was found to be about three times that of calcium propionate. Prolongation of shelf life reached 117% for sorbic acid and 63 % for calcium propionate, when salt and sugar were fixed to their basic levels. Vegetable fibers had a detrimental effect on shelf life greatly decreasing it by as much as 65 % of the control samples (without fibers). Addition of fat and emulsifier in the dough showed a slightly negative effect on the mould‐free shelf life of bread.     

Influence of modified atmosphere packaging on the shelf life of prebaked pizza dough with and without preservative added

The possible effect of different modified atmospheres on the shelf life of prebaked pizza dough, with and without added calcium propionate, was investigated. Three packaging atmospheres were tested: 20% CO2: 80% N2, 50% CO2: 50% N2, 100% CO2, and air (control). Samples were examined daily for visible mold growth and analysed after 2, 8, 17 and 31 days throughout storage (15-20 degrees C and 54-65% relative humidity, RH) for changes in gaseous composition, pH and microbial populations (mesophilic aerobic and anaerobic bacteria, lactic acid bacteria (LAB), and yeasts and molds). Microbiological results showed that molds had a greater sensitivity to CO2 than bacteria and yeasts. Products containing calcium propionate did not show mold growth throughout storage (31 days) when packaged in air or in CO2-enriched atmospheres (20, 50 and 100%). However, in pizza dough without preservative (calcium propionate), mold growth was evident after 7 days, except under 100% CO2 atmosphere (13 days) regardless of the packaging atmosphere. From these results we conclude that the addition of calcium propionate had more and decisive influence on the shelf life extension of prebaked pizza dough.