威代尔冰酒葡萄原料迟采过程中理化指标的变化

以贺兰山东麓产区威代尔葡萄(Vidal)为研究对象,测定其在迟采过程中果实糖度、酸度、pH、百粒重、出汁率等理化指标的变化。结果表明:随着原料的过熟,果穗果粒出现了变化,有的果粒出现干化,有的果粒出现了贵腐,糖度逐渐上升,酸度、百粒重、出汁率等下降,后熟60d左右达到401g/L的糖度(以葡萄糖计)。在贺兰山东麓的气候条件下,原料在经过60d左右的迟采情况下,可达到生产冰葡萄酒的原料要求。     

酿酒葡萄品种威代尔在宁夏的引种栽培报告

1999年宁夏从美国引进抗寒酿酒葡萄品种威代尔(Vidal blanc),开展了种苗繁育、保护地栽培、露地栽培、区域试验和酿酒试验。经过12年试验栽培,调查研究了其生物学和栽培学性状,结果表明威代尔在宁夏自然条件下表现出抗寒、抗病、耐盐碱、耐瘠薄和早产、丰产等特性。     

威代尔葡萄特征性香气成分2-苯乙醇的合成机制探讨

以酿制冰葡萄酒的主要品种——威代尔葡萄为试材,研究威代尔葡萄果实中特征性香气成分——2-苯乙醇以及合成2-苯乙醇的前体物和中间产物在成熟、后熟过程中含量的变化,并结合产地气温变化,探讨2-苯乙醇的合成机制,为进一步研究葡萄中2-苯乙醇的合成途径提供基础.结果表明:在花后130d,即当地气温骤降后苯丙氨酸含量迅速增加,同时苯乙胺含量迅速降低,2-苯乙醛含量维持在低水平浓度,而2-苯乙醇含量显著提高.由此得出结论:威代尔葡萄后熟期间特征性香气成分2-苯乙醇的合成源自苯丙氨酸,其中间产物可能为苯乙胺和2-苯乙醛.2-苯乙醇的合成,含量的显著提高与产地气温的骤降有关联.     

葡萄果实成熟过程中含氮化合物的变化

本文通过对琼瑶浆、玫瑰香、赤霞珠、小白玫瑰4个葡萄品种在果实成熟过程中硝态氮、氨态氮、总氮含量的测定,探讨了葡萄果实成熟过程中不同氮化物的变化.结果表明:4个品种在果实成熟过程中果肉和种子中硝态氮、氨态氛、总氮含量呈逐渐升高的趋势,接近成熟时其含量趋于稳定;4个品种果实种子中的硝态氮、氨态氮、总氮含量均高于果肉中的含量.     

冷藏后南果梨常温后熟期香气成分变化

研究0℃冷藏70d后南果梨常温后熟阶段香气成分的变化。使用固相微萃取法提取香气成分,气相色谱-质谱法对提取成分进行分析,结果表明:对于常温下不采用冷藏后熟的果实而言,采后未熟果实中仅能检测到4种香气成分,果实自然成熟至最佳风味期时香气成分增加至16种,其中,酯类物质占75%,之后随着果实的后熟衰老,香气成分种类又逐渐减少。冷藏后,常温后熟过程中,果实的香气成分也在逐渐形成,其总体变化趋势与采后直接常温后熟过程相似,并且果实仍然可以正常后熟。但冷藏对乙酸乙酯、己酸乙酯和丁酸乙酯3种香气成分的影响较大。与采后直接常温后熟相比,在最佳风味期时,冷藏造成丁酸乙酯和己酸乙酯相对含量减少,乙酸乙酯相对含量增加。     

猕猴桃果实后熟过程中不同部位营养成分的变化

猕猴桃果实的成熟调控机理较为清晰,但后熟过程中不同部位营养成分变化尚不清楚。以‘贵长’猕猴桃果实为试材,当可溶性固形物含量达到6.5%时采收,采后置于(25±1)℃贮藏,每隔4 d取样分析其呼吸速率和食用品质,按无籽果肉、带籽果肉和果心3部位取样,分析其营养成分。结果表明,采收时不同部位营养成分存在显著差异。猕猴桃果实后熟过程中,可溶性固形物含量和固酸比持续升高,糖酸比先升高后降低。不同部位的营养成分均发生显著变化,除带籽果肉多酚含量持续上升,果心叶绿素含量持续下降外,不同部位其他营养成分含量均呈先升高后降低的趋势,但其峰值在不同时间到达。猕猴桃果实后熟过程中营养成分在不同部位进行代谢及转移,影响果实的品质。     

冰葡萄酒原料威代尔后熟过程中质量指标变化研究

本文以贺兰山东麓产区森淼兰月谷酒庄威代尔葡萄(Vidal)为研究对象,通过测定其后熟(延迟60 d)过程中果实理化指标(百粒重、百粒体积、出汁率、p H值、还原糖、总酸)的变化以及对其葡萄汁感官质量(颜色、香气)的品评,研究冰葡萄酒原料的理化及感官指标的变化规律,为适时采收提供依据。结果表明:随着原料的后熟,葡萄果粒颜色由绿变黄再变为红棕色,果实香气表现更加复杂;还原糖、p H值呈现上升趋势,百粒重、百粒体积、出汁率、总酸呈现下降趋势。因此,在贺兰山东麓产区的气候条件下,延迟60 d采收可以达到生产优质冰葡萄酒的要求。     

柿子后熟过程中生理代谢和品质变化及乙烯的催熟效果

牛心柿后熟过程中,果实呼吸强度和乙烯释放速率出现明显跃升现象,果实硬度、总酸度和维生素C含量下降,还原糖和总糖含量上升。果实的品质变化早于生理代谢变化。1000 10~(－6)乙烯处理明显促进果实后熟,可作为柿子产销中提高商品质量的一项技术措施。     

兔肉宰后成熟过程中理化性质的变化

本实验以兔后腿和背最长肌为材料,研究兔肉宰后成熟过程中理化品质的变化,为兔肉成熟工艺的制定提供理论依据。结果表明：依pH值和色泽指标变化判断,兔肉成熟时间以72 h为宜;依肌原纤维小片化指数（myofibrillar fragmentation index,MFI）和剪切力指标判断,兔肉成熟时间以96 h为宜;依挥发性盐基氮（TVB-N）的变化判断,兔肉成熟时间应≤72 h。从多种因素综合考虑,兔肉的最佳成熟时间为72 h。     

宰后成熟过程中猪肉保水性的变化

以三元猪背最长肌为研究对象,在第4、8、12、16、20、24、28、32和36 h分别检测蒸煮损失率、滴水损失率、贮藏损失率、剪切力值和pH值的变化情况,研究宰后成熟过程中猪肉保水性的变化规律。结果表明,蒸煮损失率呈先升高后降低的趋势,在第20 h蒸煮损失率达到最大值32.80%;贮藏损失率和滴水损失率呈先下降后上升再下降的趋势;剪切力值在4~12 h内显著性上升（p<0.05）,且在12 h达到最大62.29 N;pH值呈整体先下降后上升再下降最后趋于稳定的变化趋势;其中,成熟时间与剪切力值呈显著负相关（p<0.01）,pH值与蒸煮损失率呈极显著负相关（p<0.01）,滴水损失率与贮藏损失率呈较高的相关性（p<0.01）。综合指标,猪肉在宰后成熟36 h内保水性有先变弱后增强的趋势,在12~16 h内进入僵直高峰点,随后进入解僵成熟期。该研究结果可为后续深入研究宰后成熟过程中猪肉嫩度变化规律及机理提供基础指标和参考依据。     

冷冻豆腐熟化期间的质构变化

本文主要研究了豆腐在一般冷冻和快速冷冻情况下熟化期内的质构变化情况,并得出快速冷冻豆腐的弹性要比一般冷冻的好。     

Viscoelastic Property Changes in Cheddar Cheese During Ripening

The rheological properties of pasteurized and raw milk Cheddar cheese were studied using oscillatory dynamic measurements, and a specially designed rheometer fixture that prevented specimen slippage. Dynamic measurements within the linear viscoelastic range were made throughout ripening. Within-cheese changes, as related to ripening time, as well as between-cheese-type differences in G’ and G” were observed. Differences in rheological characteristics were attributed to proteolytic activities in Cheddar cheese during ripening. Specific peptide profiles associated with proteolysis during ripening may affect cheese rheological properties.     

Changes in Chemical Constituents of Kiwifruit During Post-Harvest Ripening

Kiwifruit (Actinidia chinensis Planch, Hayward cultivar) were ripened at 20°C under a stream of water-vapor saturated air containing 5 ppm ethylene gas. A remarkable rapid softening in the texture and rising of the soluble solids were observed in 24 hr. The total acidity, starch and amylose content decreased during ripening. Both fructose and glucose increased from 2.7% to 5.0% after 5 days of ripening. Sucrose content increased from 0.45% to 2.22% on the second day, then decreased to 1.19% after 5 days. No significant change in chlorophyll and total solids were observed throughout the experiment. There were stepwise decreases in the L and b_L values during ripening. The ascorbic acid content decreased from 210 to 190 mg per 100g fresh fruit after 5 days of ripening.     

Organic Acid Changes During Ripening of Processing Peaches

Organic acids and their changes during peach (Prunus persica L. Batsch) fruit ripening were quantified by HPLC for clingstone culti-vars,‘Babygold 5’and‘Babygold 7′, and a freestone cultivar,‘Cresthaven’. At full maturity,‘Babygold 5’and‘Babygold 7’had about 60% malic, 20% citric and 19% quinic acid; whereas‘Cresthaven’had similar amounts of all three organic acids (37, 3.5 and 28%, respectively). During fruit ripening,‘Babygold 5’and‘Babygold 7’increased in malic acid and decreased in citric and quinic acids, whereas,‘Cresthaven’showed little change in these organic acids.     

契达干酪成熟过程中游离钙、游离磷与其他指标的相关性研究

研究了契达干酪成熟过程中游离钙/总钙、游离磷/总磷的变化,并与干酪成熟的标志性指标——蛋白质水解和质地(包括剪切力和硬度)变化的相关性进行了初步研究。研究结果表明:在干酪成熟过程中,游离钙/总钙与WSN/TN在P<0.001水平下正相关,与剪切力和硬度在P<0.001水平下负相关;游离磷/总磷与WSN/TN在P<0.001水平下负相关,与剪切力和硬度分别在P<0.001和P<0.01水平下正相关。     

Changes in Volatile Compounds and Some Physicochemical Properties of European Cranberrybush (Viburnum opulus L.) During Ripening Through Traditional Fermentation

The changes in volatile compounds and some physicochemical properties of European Cranberrybush (Viburnum opulus L.) were investigated during traditional fermentation. Using the principal component analysis (PCA), relations between volatile compounds and fermentation were associated with dynamics of these compounds. In total, 58 volatile compounds were identified, 3‐methylbutanoic acid (25.4% to 66.4% of identified volatile compounds) being the major constituent in raw, 2‐, 3‐, and 4‐mo fermented European Cranberrybush fruits, while 2‐octanone was dominant in 1‐mo fermented sample with a 30% of the total identified volatiles. The amount of total volatile compounds was increased in the 1st month of fermentation and then decreased gradually in the following months. Acids were the dominant volatile compounds in raw and 3‐ to 4‐mo fermented European Cranberrybush. Ketones and alcohols had the highest percentage in total volatile compounds in the 2nd and 3rd months of fermentation, respectively.     

Nonenzymatic Browning and Chemical Changes During Grape Juice Storage

The effect of storage on juice concentrate from 2 red grape (Merlot and Criolla) and 1 white grape (Yellow Muscat) varieties on color and chemical composition, at temperatures ranging from 10 to 30 °C, was investigated. Color deterioration as A420 occurred at a faster rate in juice made with Merlot variety. The same was true when the pigment destruction as A520/420 was studied. Total reducing sugar, fructose‐to‐glucose ratio, and proline (the only significant amino acid present in grape juice) remained practically constant during storage. The hydroxymethyl‐furfural (HMF) buildup reaction proceeded faster in Criolla grape juice. Independent of variety, a detectable amount of HMF was produced only after 12 wk of storage at any temperature.     

Compositional Changes in Mango Fruit During Ripening at Different Storage Temperatures

Chemical changes in Haden, Irwin, Kent, and Keitt mangos stored at 16-28°C and 85-90% RH were followed to determine the optimum storage and ripening conditions. Weight loss was slightly higher at 25° and 28°C than at 16-22°C. Breakdown in acidity during ripening was slower at 16°C. Vitamin C showed two basic trends; a general decrease as in Haden, Irwin, and Keitt or a steady increase as in Kent. Total and β-carotenoids were significantly higher at 22-28°C than at 16-20°C. No significant differences were observed with respect to carbohydrate and soluble solids content. However, sucrose increased spectacularly at all temperatures contributing most to the increase in sweetness. The pattern of chemical changes were strikingly similar in all the varieties. Temperatures of 20-22°C and 85-90% RH are recommended for storage and ripening of mangos to obtain sufficiently acceptable quality attributes.