温度波动对灵武长枣贮藏品质的影响

为研究温度波动对灵武长枣采后贮藏品质的影响,将灵武长枣进行自发气调包装,然后在(0±0.1)、(0±0.5)、(0±1)℃下贮藏。通过测定灵武长枣贮藏期间感官品质、丙二醛、V_C、可滴定酸、可溶性固形物和电导率等来比较不同贮藏温度的保鲜效果。试验结果表明:(0±0.1)℃下贮藏的灵武长枣保鲜效果最好,有效维持灵武长枣的感官品质,减缓了V_C的降解,同时有效抑制可滴定酸和可溶性固形物含量的降低以及丙二醛的增长。     

热协同超高压加工鲜榨苹果汁贮藏过程中色泽稳定性研究

通过HPLC等方法,分析用热协同超高压加工的鲜榨苹果汁中酚类和V_C等物质在贮藏中的变化,发现果汁在贮藏中发生的非酶褐变主要是由酚类的氧化聚合引起的,可通过低温贮藏加以控制。聚原花色素、表儿茶素、绿原酸和V_C的损失以及果汁的褐变随贮藏时间的延长和温度的升高而加剧。果汁颜色变化先快后慢,L~*值降低,a~*值升高,b~*值变化较小。氨基酸也参与了褐变反应,但Maillard反应不显著。缩合单宁的平均聚合度随贮藏时间的延长和温度的升高而变大。粒径分析表明贮藏过程中有新的颗粒产生。     

苹果沙棘复合果泥配方优化及品质分析

以苹果和沙棘原浆为原料,可溶性固形物、褐变度、感官评分为评价指标,通过单因素、Box-Behnken响应面设计优化苹果沙棘复合果泥配方。同时采用顶空固相微萃取-气相色谱-质谱联用技术分析苹果沙棘复合果泥的香气构成。试验优化果泥配方:苹果浆为基料,添加沙棘原浆7%、白砂糖12%、果胶0.3%(均为质量分数),该配方所制备果泥样品可溶性固形物为33%,pH值为3.35,亮度值(L^*)为50.45、红绿值(a^*)为3.93、黄蓝值(b^*)为24.83,感官评分87分,色泽金黄、口感细腻、酸甜适口。香气构成分析结果表明,苹果沙棘复合果泥样品中共定性定量57种组分,主要包括醇类、酯类、醛类、酮类、萜烯类。香气活性值(odor activity value,OAV)大于1的组分包括1-辛烯-3-醇、芳樟醇、正己醛、2-辛烯醛等22种香气化合物,可赋予产品青香、柠檬、苹果、紫丁香和茉莉香气。与苹果果泥相比,苹果沙棘复合果泥增加了12种主体香气(OAV>1),果香和花香更浓郁。     

槟榔不同温度贮藏特性研究

以海南槟榔为试材,研究11、13、15、20℃条件下的品质变化。结果表明:贮藏35 d内各温度处理均有一定效应,其中13℃的综合评价最佳,贮藏期末腐烂率、L*值、SSC(可溶性固性物含量)、V_C(维生素C)和槟榔碱含量分别为21.39%、34.58、18.3%、3.8 mg/g、0.35%。11℃下个别槟榔果实出现冷害症状,20℃果实贮藏品质最差。     

不同温度储藏下番茄酱色泽变化及其动力学研究

对马口铁罐装番茄酱在不同温度下储藏,其色泽随贮藏时间的变化及其动力学进行了研究。研究显示,随着储藏温度增加,番茄酱的褐变指数随着储藏时间上升较快,亮度L*值、红值a*和黄值b*下降较快,色差值△E上升较快,并对不同温度储藏下马口铁罐装番茄酱进行褐变动力学分析,其中色泽参数L*值、a*、b*符合一级反应,色差值△E符合零级反应。     

沙棘原浆苹果酸-乳酸发酵过程中理化指标及抗氧化能力的变化

以沙棘原浆为原料,利用酒酒球菌CICC 6066进行苹果酸-乳酸发酵(malolactic fermentation,MLF),研究发酵过程中(25℃,8d)沙棘原浆活菌数、pH值、有机酸、单糖、黄酮醇、酚酸及超氧化物歧化酶(superoxide dismutase,SOD)和抗氧化活性的变化.结果 表明,酒酒球菌发酵...     

沙棘原浆发酵功能饮料的研制及其品质特征和抗氧化活性评价

以沙棘原浆为原料,采用酒酒球菌进行苹果酸-乳酸发酵,并对发酵原浆进行调配,通过单因素试验和响应面试验、正交试验分别优化沙棘发酵功能饮料的发酵工艺及饮料配方,进一步对产品的理化指标、抗氧化活性及风味特征进行分析.结果 表明,沙棘原浆发酵最佳工艺参数为:接种量5.O％、发酵温度28℃、发酵时间6d、初始pH3.5,此条件下...     

沙棘酒贮藏期间非酶褐变研究

为研究沙棘酒在室温贮藏期间与非酶褐变有关的主要物质的变化及其与褐变之间的关系,通过测定其在贮藏过程中褐变度、总酚、5-羟甲基糠醛(5-HMF)、抗坏血酸(VC)、还原糖、总酸和溶解氧等指标变化,采用相关性分析和通径分析,探讨影响沙棘酒贮藏过程中非酶褐变的主要原因.结果表明:在25℃下,随贮藏时间延长,沙棘酒褐变度逐渐增...     

基于绿熟番茄果实L* 值的番茄红素含量预测模型建立

为了研究绿熟番茄果实贮藏期间颜色和番茄红素含量变化的关系,通过不同温度下的贮藏实验研究基于果实明度(L* 值)的番茄红素含量预测模型。将绿熟番茄果实贮藏在283.15、288.15、298.15K 条件下,测定了果实L* 值和番茄红素含量的变化。采用指数函数和Gomportz 函数分别对不同贮藏温度下番茄果实L* 值和番茄红素含量进行曲线拟合,建立了果实L* 值和番茄红素含量与贮藏时间和贮藏温度之间的动力学模型。实验表明,指数函数和Gomportz 函数分别对番茄果实L* 值和番茄红素含量的变化具有较高的拟合精度(R2 ＞ 0.95)。在Arrhenius 动力学方程基础上得到绿熟番茄果实贮藏期间L* 值和番茄红素含量变化的活化能(Ea)分别为48.09kJ/mol 和67.06kJ/mol,复相关系数分别为0.9644 和0.9815。建立的基于果实L* 值变化的番茄红素含量的预测模型所获得的番茄红素预测值与实测值之间的平均相对误差为8.74%,小于10%。这表明,在283.15～298.15K(10～25℃)的贮藏温度范围内,可根据番茄果实采后L* 值的变化对番茄红素的含量进行预测。     

黄皮原浆超高压和热杀菌的比较分析

以黄皮原浆为研究对象,分别用超高压(Highhydrostaticpressure,HHP)和热处理(heattreatment,HT)进行杀菌,比较处理前后及4℃贮藏期间黄皮原浆各理化指标的变化。贮藏期结束时超高压组和热处理组菌落总数分别为67.36、43.49CFU/m L,表明黄皮原浆超高压600 MPa/5 min的杀菌能力与热处理85℃/30 min相当;pH、可滴定酸(TA)、可溶性固形物含量(TSS)在两种处理前后及贮藏期间均无显著(p0.05)变化;两种处理后的总酚、抗坏血酸和抗氧化能力在贮藏期间均呈下降趋势,贮藏期间超高压组总酚、抗坏血酸分别下降了11.71%、9.45%,热处理组下降了19.61%、18.92%,说明超高压能更好的保留黄皮原浆中总酚和抗坏血酸含量,减少抗氧化能力的损失;热处理使黄皮原浆中果胶含量提高了23.15%,而超高压处理对果胶含量无显著影响,但能更好的保留原浆贮藏过程中果胶含量;黄皮原浆中有机酸主要为酒石酸、苹果酸、柠檬酸,且酒石酸含量最高,为13.95mg/g,热处理组对有机酸的影响小于超高压组。研究结果为超高压和热处理应用于黄皮原浆加工提供理论依据。     

OPTIMIZING THE DEHYDRATION CONDITIONS OF GREEN BELL PEPPERS (CAPSICUM ANNUUM L.): QUALITY CRITERIA

Green bett pepper (Capsicum annuumL.) dices were dehydrated at different dry bulb air temperatures (55, 60, 65, 70 and 75C) and relative humidities (15, 20, 25, 30, 35 and 40%). Color, L-ascorbic acid and sugar retention were adversely affected by temperature and RH during dehydration. Loss of color and reduction in L-ascorbic acid and sugar were more prominent at the higher temperatures (70 and 75C) used. Sugar retention was negatively affected by drying, in that levels decreased, but no distinguishable pattern existed between the drying conditions and sugar retention. Optimum quality (maximum retention of color and L-ascorbic acid) green peppers were attained at drying conditions of 55 and 60C (15–40% RH) as well as at 65 and 70C (15% RH).     

Der L-Ascorbinsäuregehalt und andere Qualitätsmerkmale in tiefgefrorenen und getrockneten Erdbeeren Fragaria x ananassa Duch.

L-ascorbic acid and other quality criteria in frozen and dehydrated strawberries Fragaria x ananassa Duch. L-ascorbid acid contents and other quality criteria were measured in six cultivars of frozen and dehydrated strawberries. The drying method used was based on the energy saving principle of low-temperature dehydration in a closed cycle with a heat pump connected. The quality of the six cultivars varied, especially concerning L-ascorbic acid contents. On average 69 mg L-ascorbic acid were found in 100 g frozen berries, with higher values for ‘Zefyr’ (94 mg) and ‘Bounty‘ (89 mg). The loss of L-ascorbic acid after dehydration was on average about 30%.     

Stability of Dehydrofrozen Green Peas Pretreated with Nonconventional Osmotic Agents

ABSTRACT: Green peas were submitted to osmotic pretreatments in carbohydrate-salt syrups to evaluate the effect of alternative agents on quality and assess the stabilization accomplished during subsequent storage in a wide temperature range-down to −24°C, including the −3 to −12°C detrimental zone. Green color and L-ascorbic acid loss were kinetically studied, and their temperature dependence was modeled by Arrhenius and Will-iams-Landel-Ferry equations. Dehydrofrozen samples exhibited significantly improved stability, with the rate of L-ascorbic acid loss, being reduced by as much as 3-fold for peas osmotically pretreated with oligofructose, trehalose, and maltitol systems. The cryostabilization results are discussed in relation to glass transition behavior of the modified osmodehydrofrozen food matrix.     

鱼香肉丝工业化生产胡萝卜护色工艺优化

为防止鱼香肉丝中胡萝卜褐变,尽量维持胡萝卜明亮的颜色,该研究以色差值和感官评分为考查指标,比较了乙二胺四乙酸二钠(EDTA-2Na)、L-抗坏血酸(V_C)、异抗坏血酸钠和柠檬酸对鱼香肉丝中胡萝卜的护色效果;研究了其质量分数、浸泡时间和温度对胡萝卜的护色效果。通过单因素与正交试验结合确立最适合胡萝卜的护色剂复配配方为：柠檬酸0.3%,乙二胺四乙酸二钠(EDTA-2Na)0.4%,L-抗坏血酸(V_C)0.3%,异抗坏血酸钠0.2%。其中,柠檬酸浓度对护色效果影响最大,异抗坏血酸钠影响最小;护色条件为25℃、30 min;在此护色条件下处理的胡萝卜的色差变化最小(ΔE值为4.19)。将胡萝卜与护色液以重量比1:4的比例在25℃环境下浸泡30 min,后通过漂烫、冷却、脱水,再制成鱼香肉丝,其中的胡萝卜颜色和品质保持较好。该研究结果可为鱼香肉丝的工业化生产提供理论基础。     

ε-聚赖氨酸和L-抗坏血酸处理对鲜切菠菜品质的影响

为探究ε-聚赖氨酸和L-抗坏血酸处理对鲜切菠菜保鲜效果的影响,根据货架期结果,在不同质量浓度梯度和组合的ε-聚赖氨酸和L-抗坏血酸处理组中（共16?组）筛选得到3?组保鲜液,分别为B组（0.05?g/L ε-聚赖氨酸溶液）、E组（10?g/L L-抗坏血酸溶液）、K组（0.05?g/L ε-聚赖氨酸＋10?g/L L-抗坏血酸溶液）。而后通过抑菌圈实验结合理化指标、抗氧化酶活性,研究不同保鲜液对鲜切菠菜品质的影响。结果表明：抑菌效果为K组＞B组＞E组;调控活性氧代谢效果为K组＞E组＞B组。0.05?g/L?ε-聚赖氨酸和10?g/L?L-抗坏血酸溶液联合应用于鲜切菠菜具有协同增效的作用,可延长货架期至12?d,0.05?g/L?ε-聚赖氨酸通过抑菌从而延长鲜切菠菜货架期至11?d;10?g/L L-抗坏血酸溶液主要通过改善鲜切菠菜活性氧代谢从而延长鲜切菠菜的货架期至10?d。     

Application of ultrasound-assisted thermal processing for preservation and quality retention of liquid foods

A continuously working pilot plant-scale prototype was used to evaluate the effects of continuous-flow ultrasound-temperature treatment for bacterial decontamination of model suspensions and various liquid food systems such as milk, fruit, and vegetable juices. Escherichia coli K12 DH 5 alpha and Lactobacillus acidophilus were used as test microorganisms. In addition, treated juices were investigated for damage caused by heat or ultrasound-induced degradation of sensory and nutritional properties after treatment and storage. Changes in color and destruction of heat-labile and slightly oxidizable L-ascorbic acid content were monitored as an index to measure processing effects. Results were assessed with respect to the total energy requirement and compared with those using a conventional, indirect heating method having similar processing conditions. For the bacteriological process evaluation, the temperature- and time-dependent process lethality was used as the basis; for the quality- and energy-related investigations, the degree of bacterial inactivation was used. At identical degrees of bacterial inactivation, the ultrasound-assisted thermal treatments required a lower processing temperature than treatment with conventional thermal processing. However, according to energy balances, the total energy consumption was not reduced compared to conventional heating. Indications for a positive influence on shelf life, with improvements in surface color stability (lightness) and L-ascorbic acid retention, were found among quality parameters of treated orange juice.     

螯合剂对L-抗坏血酸氧化作用影响的研究

研究了食品中常用螯合剂对L-抗坏血酸氧化作用的影响，研究结果表明：螯合剂螯合作用受pH值影响较大，受温度影响较小。面团的拉伸试验表明螯舍剂有效地延缓了L-抗坏血酸的氧化作用。面包烘焙试验进一步证实螯合剂可以使L-抗坏血酸氧化作用变慢，螯合剂与L-抗坏血酸的协同作用可以提高面包烘焙品质，其中柠檬酸作用最为明显。     

Ascorbic Acid Retention in Retort Pouched Green Beans

The L-ascorbic acid (AA) retention in and sensory quality of green beans processed under home-canning conditions in retort pouches and metal cans were compared. Green beans processed in cans retained slightly more AA than that processed in the pouches, possibly due to overprocessing of the pouched product. Metal cans offered better AA retention in the green beans than the retort pouches during 11 wk of storage at 21°C, due mainly to a higher rate of AA degradation occurring in the pouched product during the first week of storage. Sensory evaluation showed that the retort pouched beans were significantly better (p < 0.05) than the canned green beans in flavor, texture, and overall acceptance, but not in color.     

悬浮仙人掌果粒酸性乳饮料的研制

悬浮仙人掌果粒酸性乳饮料的最佳配方为:仙人掌粒5%,蔗糖85%,奶粉4%,柠檬酸0.32%,稳定剂(TKM21G-I)0.8%,经调配制成口感优良、风味独特、质量稳定、感觉清新的悬浮仙人掌果粒酸性乳饮料。仙人掌最佳护色工艺为:先将仙人掌粒用85～90℃,0.35g/L醋酸铜溶液热烫12min,再用1.0g/LL-抗坏血酸和0.3g/L柠檬酸对仙人掌粒协同护色,仙人掌最佳粒径为:3mm×3mm×3mm。     

Biochemical Studies on Some Chemical Characteristics of Sliced Egyptian Onions

Biochemical studies were carried out on two widely distributed Egyptian onion varieties (Behairy and Selected Giza 6). Several treatments (soaking in tap water, boiling water, cold water, warm ethanol, or sodium chloride solution) were proposed to overcome onion reddening during industrial processing. Some chemical characteristics (L-ascorbic acid, free amino acids, volatile sulfur compounds, carbonyl compounds, pungency and color) were determined in fresh, treated and stored sliced onions. Unsaturated fatty acids can be considered as a secondary source for carbonyl compounds and are involved in the formation of red pigments. Pronounced changes among hydrocarbons and little changes in sterols were due to application of various treatments and storage. In general, the most efficient treatments towards keeping onion quality were soaking the sliced onions in cold water or 5% (w/v) sodium chloride for 24 hr before onion dehydration.