不同包装材料对酸奶品质变化的影响

本实验选择了同一奶源,相同加工工艺以及同一批次的四种包装材料的屋顶盒包装酸奶,研究它们在4℃冷藏避光、4℃冷藏光照、25℃室温避光和25℃室温光照四个贮藏条件下,滴定酸度、粗蛋白含量、乳酸菌总数以及VC含量在贮藏期内的变化。实验结果表明,蓝色屋顶盒包装整体稳定性最好,其次是黄色包装,而红色包装在乳酸菌增殖和VC的保护效果上不如蓝色包装和黄色包装,白色包装效果最差。     

UHT灭菌乳在贮藏期内的品质变化

选择了市售塑料袋装UHT灭菌乳(保质期为30 d),研究了其在4℃冷藏避光、4℃冷藏光照、25℃室温避光、25℃室温光照、37℃避光,37℃光照6种贮藏条件下,贮藏期内主要理化指标和微生物指标的变化.结果表明,在整个贮藏期内.UHT灭菌乳的酸度持续增加,10～15 d酸度增长幅度最大,37℃条件下,最大酸度可达到22.14°T;在6种贮藏条件下蛋白质量分数均相对稳定;在贮藏的前10 d,试验样品细菌总数均小于1 mL-1,之后持续增长;光照与否,各取样点维生素C质量浓度差异显著.     

影响悬浮型奇亚籽饮料稳定性的因素

通过单因素试验及正交试验研究复配稳定剂、温度、p H对奇亚籽饮料悬浮稳定性的影响。结果表明,悬浮型奇亚籽饮料在温度70℃条件下,奇亚籽悬浮率达79.0%;当温度为100℃时,奇亚籽悬浮率仅为58.7%,说明高温对奇亚籽饮料的悬浮稳定性有破坏作用,且加热时间不宜过长;当pH为4～6时,奇亚籽饮料稳定性良好且稳定,而在强酸强碱条件下稳定性易被破坏;通过正交试验优化得出影响悬浮型奇亚籽饮料稳定性因素的顺序:pH温度复配稳定剂,且最优条件温度为温度65℃、pH 5、复配稳定剂0.04%,在此条件下奇亚籽饮料稳定性最佳。     

荔枝原汁保藏工艺探讨

本文通过检测经加热杀菌和钝化酶处理的荔枝原汁在冷藏、冻藏、室温贮藏及添加柠檬酸、异VC、山梨酸钾、NaHSO3等条件下,VC、总糖、总酸和褐变度变化情况,并进行感官评价,探讨荔枝原汁保藏工艺。结果表明,荔枝原汁在冻藏（－20℃）半年后,其营养成分和色香味基本保持稳定,品质最好;冷藏（0～4℃）过程中,其VC和总糖有一定损失,总酸和褐变度略有上升,贮藏半年后色香味有所下降,品质较冻藏差;室温（30℃左右）贮藏的荔枝原汁虽然添加不同保藏剂处理,但贮藏1个月后相继产气败坏。试验结果对荔枝原汁生产和贸易有一定参考价值。     

不同贮藏方式对鲜切大白菜食用品质的影响

为探究不同贮藏方式对于鲜切大白菜食用品质的影响,研究采用不同包装及贮藏温度对鲜切大白菜进行处理,通过测定其感官品质、抗坏血酸、可溶性蛋白质、可溶性固形物及亚硝酸盐含量的变化,探究不同贮藏方式对鲜切大白菜食用品质的影响。结果表明：两种冷藏（4±1℃）条件下（即冷藏与冷藏PE）鲜切白菜的感官品质均显著优于两种室温（18±2℃）条件（即室温与室温PE）（P≤0．05）,且两种冷藏条件下可明显延缓抗坏血酸、可溶性蛋白质、可溶性固形物含量的下降,抑制亚硝酸盐含量的升高。其中,以冷藏PE贮藏方式对保持鲜切白菜的食用品质效果最佳。     

不同贮藏温度对肉制品中亚硝酸盐含量的影响

本文研究不同贮藏条件对腊肉、香肠、火腿肠、西式火腿和熏烤肉中亚硝酸盐含量的影响。比较了5种肉制品在冷冻(-18℃)、冷藏(4℃)、常温(25℃)条件下贮藏时,其亚硝酸盐的含量随着贮藏时间的变化趋势。结果表明:随着贮藏时间的延长,肉制品中的亚硝酸盐含量呈下降趋势,且室温条件下亚硝酸盐的含量比冷藏低,冷藏条件下的亚硝酸盐含量比冷冻低。     

荔枝果汁饮料生产工艺研究

通过检测荔枝原汁在不同温度贮藏过程中VC和褐变度的变化,并结合感官评价,探讨荔枝原汁保藏工艺。同时通过正交试验优选荔枝果汁饮料工艺配方。结果表明,荔枝原汁在冻藏条件下品质最好;冷藏(0～4℃)品质较冻藏差;室温(30℃左右)不适宜荔枝原汁的贮藏。荔枝果汁饮料较佳的配方为荔枝原汁≥25%,糖浓度11%～13%,酸度0.2%左右。     

红曲米粉在软欧包的着色研究

为探究红曲米粉在软欧包着色及应用，设置五个条件(常温曝光、常温避光、冷藏曝光、冷藏避光、冷冻避光)贮藏，采用单因素和正交试验法，考察添加红曲米粉对成品口感、色差、质构、风味物质、抑菌影响。研究发现：添加0.5%红曲米粉，在pH8,95%乙醇浓度，冷冻避光贮藏，软欧包感官、色泽、质构、风味、抑菌最佳。不同条件贮藏33 d，软欧包L^*、b^*值增大，a^*值减小；第一循环硬度增大；弹性减小；风味独特；常温曝光、常温避光贮藏，第4 d已霉变；冷藏曝光、冷藏避光、冷冻避光贮藏至第33 d，菌落总数和霉菌均未超标，抑菌效果良好。红曲米粉在软欧包中具有强着色、抑菌作用，应用前景大，为新型天然色素在烘焙产品应用开发新路径。     

超高温瞬时灭菌对刺梨汁营养物质与贮藏稳定性的影响

以鲜榨刺梨汁为原料,研究对比了超高温瞬时灭菌(UHT)后与未灭菌的刺梨汁在4℃和常温避光条件下4组样品贮藏的品质变化,对刺梨汁Vc、SOD、单宁、pH值、总酸、可溶性固形物与微生物指标进行8周的动态监测。结果表明,UHT灭菌的刺梨汁在4℃冷藏与常温避光贮藏8周后,Vc保留率分别为90.91±0.7%与87.58±0.9%;SOD酶活性保存率分别为89.9±1.81%与85.82±3.49%;未经过UHT处理的刺梨汁在4℃冷藏与常温避光贮藏8周后,Vc保留率分别为78.89±0.43%与41.19±3.1%;SOD酶活性保存率分别为51±3.78%与41.8±7.33%;四组样品pH值均呈下降趋势,总酸含量均呈先上升后稳定的趋势;此外,在不同贮藏温度下UHT处理与未灭菌对单宁含量与可溶性固形物含量几乎没有影响(P>0.05);UHT处理组菌落总数与大肠杆菌均未检出,未灭菌刺梨汁菌落总数在第4周开始出现增长。结果表明UHT处理能有效保留刺梨汁中营养与生物活性物质,延长产品货架期;低温有利于刺梨产品的保藏。     

贮藏方式对武夷岩茶梅占生化成分及感官品质的影响

以武夷岩茶梅占为试验材料,研究室温(3℃～30℃左右)贮藏和冷藏方式对武夷岩茶生化成分与感官品质变化规律的影响,为贮藏武夷岩茶提供理论与实践依据。结果表明:贮藏期间茶多酚含量、儿茶素含量、简单儿茶素含量、酯型儿茶素含量、咖啡碱含量呈下降趋势;茶红素含量、茶褐素含量、茶叶感官品质得分呈上升的趋势。室温贮藏(3℃～30℃左右)处理的茶叶感官品质得到提升主要体现在香气逐渐变为浓长、火气逐渐褪去;滋味逐渐由醇厚微涩转变为醇厚甘爽。冷藏处理的茶叶感官品质得分低于室温贮藏(3℃～30℃左右)处理,主要体现在香气带火气、滋味微涩。综上,室温贮藏(3℃～30℃左右)武夷岩茶优于冷藏。     

Physical and sensory properties of lemon-flavored acidic beverages formulated with nonfat dry milk during storage

Sensory and physical properties of 2 lemon-flavored beverages with 5% and 7.5% wt/wt nonfat dry milk (NFDM) at pH 2.5 were studied during storage. The 2 beverages had similar volatile compounds, but the 5% NFDM had higher aroma and lemon flavor, with a preferred appearance by consumers due to the lower turbidity and viscosity. After 28 d of storage at 4°C, lemon flavor decreased in the 5% NFDM beverage but was still more intense than the 7.5% one. During 70 d of storage, no microorganisms were detected, and the beverages were more stable when stored at 4°C than at room temperature according to changes of physical properties measured for appearance, turbidity, color, particle size, zeta potential, rheological properties, and transmission electron microscopy morphology. Findings of the present study suggest that NFDM may be used at 5% wt/wt to produce stable acidic dairy beverages with low turbidity when stored at 4°C.     

Effects of Calcium Addition on Stability and Sensory Properties of Soy Beverage

Pasteurized or thermally processed soy beverages (6% soy solids) were fortified to a comparable level of cow's milk with 25 mM (or 30 mM) calcium using mixtures of calcium citrate and tricalcium phosphate. These fortified pasteurized products had acceptable sensory properties. Addition of these calcium salts did not adversely affect protein stability of the beverage. Calcium citrate addition caused a decrease in beverage pH and viscosity. Thermally processed (still retort and agitort) canned beverages containing calcium salts were stable for 6 months when stored at 1°C or at room temperature.     

不同杀菌温度及贮藏条件对卤蛋菌落总数和脂肪酸组分的影响

本实验以真空包装卤蛋为研究对象,进行95、105 ℃和121 ℃不同温度杀菌,并分别于4 ℃和25 ℃下进行贮藏（121 ℃杀菌仅在25 ℃下贮藏）,测定并分析各样品在贮藏期间内菌落总数和脂肪酸组成的变化。结果表明：各杀菌温度都可在杀菌完成时有效杀灭活体细菌,各组样品菌落总数均小于10 CFU/g;相较于95 ℃杀菌样品,105 ℃和121 ℃杀菌样品的多不饱和脂肪酸总含量分别下降了1.56%和6.83%;随着贮藏时间延长,受杀菌温度、贮存温度、微生物种类、微生物增殖及氧化水解反应等因素的影响,各组样品脂肪酸组成发生差异性变化。95 ℃杀菌、25 ℃贮存的样品仅可保存15 d,且脂肪酸劣变速率最快;105 ℃杀菌、25 ℃贮存的样品可保存75 d,脂肪酸劣变速率较慢;95 ℃杀菌、4 ℃贮存的样品可保存90 d,但脂肪酸劣变速率较快;121 ℃杀菌、25 ℃贮存的样品贮藏90 d时仍未检测到微生物增殖,贮藏期间内脂肪酸总量保留较好,但初始多不饱和脂肪酸水平较低;105 ℃杀菌结合4 ℃贮存的样品在贮藏90 d时同样未检测到微生物增殖,且贮藏期内总脂肪酸保存率最高,可作为生产高营养水平和长保质期卤蛋较好的应用技术。     

贮藏温度及时间对不同类型商品乳酸度的影响

为研究不同贮藏温度及时间对不同类型商品乳酸度的影响情况。选取超高温(UHT)灭菌乳、巴氏灭菌乳、乳饮料、酸牛奶各10盒,将每种类型的商品乳分成2组,开封后进行贮藏。一组放入0~4℃的冰箱冷藏,另一组放在常温下贮藏。分别在0, 1, 2, 3, 4, 5和6 d测定各组商品乳的酸度。结果表明,酸牛奶、UHT灭菌乳和巴氏灭菌乳放在常温下贮藏时酸度分别在第1,第3和第3天出现显著性差异(p<0.05),在低温下贮藏时酸度均未出现显著性差异(p>0.05)。乳饮料在常温和低温下贮藏1 d后酸度均出现显著性差异(p<0.05)。4种类型的商品乳放在低温下贮藏时更能保持酸度的稳定。     

胡萝卜复合汁乳酸发酵饮料贮存稳定性的研究

将发酵后的胡萝卜复合汁乳酸饮料分别存放在室温和冷藏2种条件下，定期测定饮料的糖度、酸度、风味及所含活菌数的变化情况。通过6次检测得知：随贮存时间延长，饮料糖度逐渐降低，室温贮存降低幅度大于冷藏；酸度逐渐升高，室温贮存升高幅度较大；双乙酰含量前期升高，后期基本稳定；活菌数渐减，但冷藏条件下饮料活菌数远高于室温贮存。     

不同茶饮料贮藏过程中品质的变化

本文从色泽、浊度及活性成分含量三个方面分析不同茶饮料的品质变化特征，分别对高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料在不同贮藏条件下的可溶性固形物含量、透光率、浊度、色差、茶多酚含量、表没食子儿茶素没食子酸酯（Epigallocatechin gallate，EGCG）含量等指标进行测定，探究不同茶饮料在不同贮藏条件（温度、时间）下品质变化的情况。结果表明:不同茶饮料在贮藏过程中，透光率无显著变化；高酸绿茶饮料在4 ℃及25 ℃条件下贮藏，随贮藏时间的延长，浊度显著增加，贮藏至第180 d，分别增加了52.04%、34.12%，红茶饮料浊度无显著变化；不同茶饮料在贮藏过程中，随贮藏时间的延长，L*值降低，a*值及b*值增加，25 ℃条件下贮藏至180 d，高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料的L*值分别降低了31.86%、39.98%、30.22%及37.73%；茶饮料中的茶多酚及EGCG含量随着贮藏时间的延长而降低，EGCG降解程度较茶多酚高，在55 ℃条件下贮藏15 d，高酸绿茶饮料、低酸绿茶饮料、高酸红茶饮料及低酸红茶饮料的茶多酚含量分别降低9.08%、10.28%、13.39%及18.63%，EGCG含量分别下降了35.32%、42.18%、47.22%及49.03%。     

火腿理化特性及贮存性的研究

本文研究了火腿在不添加防腐剂的情况下贮存特性,成品火腿具有低pH(平5均值5.94)及高含水量(平均水分活度0.943)的特点,在0～4℃条件下,经过35天贮藏,细菌总数达3.2×104CFU/g;而在25℃条件下,经过21天贮藏,细菌总数达1.9×104CFU/g,室温条件下,火腿的保质期大大缩短。贮藏期间,产品的pH值没有发生明显变化。     

Storage stability of sterilized liquid extracts from pomegranate peel

Pomegranate marc, a byproduct of commercial juice production, has shown promise as a starting material for the recovery of health promoting phenolic compounds. The stability of aqueous extracts prepared from pomegranate marc was evaluated in preparation to directly using these extracts as nutraceuticals or food additives. The liquid extracts were produced under extraction conditions of 25 °C, water to peel ratio of 50 : 1 (w/w) for 2 min, and then sterilized at 121 °C for 10 s. Storage conditions tested included 3 different pH values (3.5, 5.0, and 7.0) and 2 packaging methods (no light and exposure to light). The extracts were evaluated for industrial (pH, total soluble solid content, and clarity), color, spectral, and antioxidant characteristics over a period of 180 d. The results showed that both pH value and packaging method significantly influenced the industrial and color characteristics of the extracts. The high pH had a negative effect on spectral and antioxidant characteristics. Therefore, the recommended storage conditions are low pH and with dark packaging to maintain the high storage stability. After 180 d of storage, extracts stored at low pH (3.5) in dark packaging still retained 67% and 58% of their total soluble phenolic concentration and antioxidant activity, compared with 61% and 43% for high pH (7.0) samples, and were composed of high concentrations of punicalagins A and B, gallic, and ellagic acids. PRACTICAL APPLICATION: The present research developed an effective recovery of phenolic compounds from pomegranate marc to be used as nutraceuticals or food additives. The aqueous extract product has good quality characteristics with high industrial and color stability, and total phenolic content and antioxidant activity, when stored at pH 3.5 in dark packaging for up to 180 d. The evaluation results of storage stability reported here are important for commercialization.     

不同气体配比气调包装对鸡蛋保鲜效果的影响

为延长鸡蛋保鲜期,研究在室温(25℃)条件下,不同配比CO2、O2、N2三元混合气体的气调包装对鸡蛋保鲜效果影响。结果表明:鸡蛋采用体积分数50%CO2、7%～11%O2、39%～43%N2的气调包装,在室温贮藏,质量损失率、蛋白pH值保持相对较低水平,哈夫单位、蛋白凝胶强度保持相对较高水平,贮藏30d鸡蛋仍保持AA级,而不包装的对照组降到了B级。     

Formation of ethyl carbamate in umeshu (plum liqueur)

Samples of umeshu, a Japanese plum liqueur made from unripe plums, shochu and crystal sugar, were stored under fluorescent light, in the dark and in the refrigerator. The amount of ethyl carbamate formed in umeshu exposed to light or room temperature was larger than that in the dark or at low temperature. The amount of ethyl carbamate formed in umeshu to which cyanide had been added was larger than that in the absence of added cyanide. Thus, the amount of ethyl carbamate formed in the umeshu was increased by not only light and higher temperature, but also cyanide. Samples of model alcoholic beverages were stored under various conditions using red, yellow and blue cellophanes. The amount of ethyl carbamate formed in the model alcoholic beverage with blue cellophane was larger than in the cases of red and yellow cellophanes. It was found that the amount of ethyl carbamate formed in the model alcoholic beverage was increased by light in the wavelength range of 375-475 nm.