鲜榨苹果汁的理化特性和感官品质相关性

以9种苹果鲜榨汁为材料,通过理化指标测定和感官评价,研究鲜榨苹果汁理化特性和感官品质之间的相关性。结果表明:1)部分理化指标之间具有显著的相关性;2)理化指标与感官特性之间存在显著的相关性:苹果香与pH值、可滴定酸含量有显著的相关性;清香与色值、总糖含量呈正相关;涩味与可滴定酸含量、多酚含量、缓冲容量成正相关,与pH值、糖酸比、固酸比呈现显著的负相关;酸味与pH值、总糖含量、可滴定酸含量、缓冲容量、糖酸比、固酸比有相关性;甜味与可溶性固形物含量(SSC)、可滴定酸含量、缓冲容量、固酸比有相关性;3)通过回归分析建立的苹果汁滋味评价模型,回归方程显著,说明鲜榨苹果汁理化特性和感官品质具有很好的相关性,可以实现理化指标对感官品质的预测分析。     

超高压激活鲜榨梨汁多酚氧化酶的酶学特性

为探究超高压加速梨汁褐变的机制,以鲜榨翠冠梨汁为原料,采用超高压（500 MPa、5 min）处理,以未处理的梨汁为对照,测定超高压处理对梨汁货架期色泽的影响,检测处理前后梨汁中溶解氧质量浓度和总酚浓度,并研究多酚氧化酶（polyphenol oxidase,PPO）的最适pH值、最适反应温度、热稳定性、米氏常数（Km）。结果表明,超高压组梨汁货架期6 h褐变（色差值（ΔE）＝1.61）,而未处理组货架期24 h仍未见明显褐变（ΔE＝0.56）。鲜榨梨汁PPO存在PPO1（pH 5.0）和PPO2（pH 7.0）两种形式,超高压加速褐变与PPO1和PPO2被激活有关：PPO1活力从6.5 U/mL上升到14.1 U/mL,上升了1.17 倍;PPO2活力从2.6 U/mL上升到25.5 U/mL,上升了8.8 倍。激活效应的内在原因是PPO存在潜在酶活性形式,其本身活力较弱甚至无活力,超高压是激活PPO潜在酶活性的外在原因之一,十二烷基硫酸钠处理、热处理等也可激活PPO潜在酶活性。超高压降低PPO的Km值,提高了其与底物之间的亲和力,从而提高酶促反应速率;PPO1与底物的亲和力1/Km从2.353 L/mol上升到46.909 L/mol,上升了18.9 倍;PPO2与底物的亲和力从2.852 L/mol上升到62.857 L/mol,上升了21.0 倍。超高压同时会降低最大酶促反应速率（Vmax）,Vmax对酶促反应速率的影响如超过Km的影响,将会表现出钝化效应。综上,超高压通过激活PPO潜在酶活力、提高PPO与底物的亲和力和酶促反应速率,加速鲜榨梨汁褐变。     

新梨7 号-南果梨混合梨汁的配比优化

该研究以新梨7 号梨汁为主要原料,添加不同体积比的南果梨汁制作混合梨汁。对混合梨汁的基本理化指标、总酚、总黄酮含量及抗氧化性进行测定,采用顶空-气相色谱-离子迁移谱（headspace-gas chromatography-ion migration spectroscopy,HS-GC-IMS）分析挥发性成分,并结合模糊数学感官评定方法,确定适宜的原料配比。结果表明,新梨7 号梨汁与南果梨汁体积比为7∶3 时,感官评价最优,综合评价总分为6.28,总酚含量、总黄酮含量较高,DPPH 自由基清除率、ABTS+自由基清除率较强,且挥发性物质的种类及含量较多。因此,确定新梨7 号梨汁与南果梨汁以体积比7∶3 进行混合梨汁加工。     

酸性电生功能水对鲜榨梨汁品质的影响

以皇冠梨为试材,利用酸性电生功能水对梨块浸泡,考察了酸性电生功能水对鲜榨梨汁品质的影响。结果表明,酸性电生功能水可将鲜榨梨汁中细菌总数降低1.5个对数值左右,并且可将梨汁中多酚氧化酶活性降低50%以上,其护色效果与添加0.1%VC的自来水相当,且梨汁风味接近对照。酸性电生功能水抑制多酚氧化酶的效果与酸性水中有效氯浓度、pH以及梨块与酸性水的比例有关。研究发现当酸性电生功能水理化指标为有效氯浓度100mg/L,pH5.0,料液比1:4时钝酶效果较为理想。     

酸性电生功能水对鲜榨梨汁品质的影响

以皇冠梨为试材,利用酸性电生功能水对梨块浸泡,考察了酸性电生功能水对鲜榨梨汁品质的影响。结果表明,酸性电生功能水可将鲜榨梨汁中细菌总数降低1.5个对数值左右,并且可将梨汁中多酚氧化酶活性降低50%以上,其护色效果与添加0.1%VC的自来水相当,且梨汁风味接近对照。酸性电生功能水抑制多酚氧化酶的效果与酸性水中有效氯浓度、pH以及梨块与酸性水的比例有关。研究发现当酸性电生功能水理化指标为有效氯浓度100mg/L,pH5.0,料液比1:4时钝酶效果较为理想。      

冷却肉低剂量辐照后的理化和感官特性变化

研究真空包装冷却猪肉经保鲜液处理和未经过保鲜液处理,再分别经1kGy、2kGy和3kGy低剂量辐照后的理化和感官特性变化,进而确定最佳的辐照处理方式以延长冷却猪肉的货架期。结果表明:经过2kGy辐照的处理组,在贮藏的过程中,鲜红色泽保持相对的稳定。冷却猪肉经过保鲜液处理 2kGy剂量辐照 冷藏(4±1℃),可以有效的延长冷却猪肉的货架期。     

杂交稻米的理化特性与食味评价的研究

本研究对籼型杂交稻米进行了包括理化特性的测定、食味感官评价及用食味计进行了成分测定和食味评价，探讨了日本常用的食味评价方法对中国产稻米的适应性，同时考察李稻米理化特性与食味的关连，并尝试建立了中国产稻米的食味推测式。     

挂面的理化特性和感官质量研究

采集全国28家企业的60份普通挂面样品,测定其理化特性、烹调特性、感官质量,分析挂面产品质量现状,比较不同小麦产区间挂面质量的差异,研究质量要素间的关系。结果表明,挂面理化特性变异较大,感官质量整体较好,色泽和食味的差异是挂面感官差异的主要方面。与南方冬麦区相比,北方冬麦区的挂面含水率较低,色泽偏黄,煮后面条的黏性、食味及总分较高。在一定范围内(色泽b*值≤18.06、烹调吸水率≤197.2%、煮面10 min后鲜重≤27.4 g),熟面条的色泽、硬度和黏性评分分别随着挂面b*、吸水率和煮面10 min后鲜重的提高而改善,但超过该范围会对面条评分产生负向作用。挂面灰分含量和烹调吸水率对色泽评分有显著影响,可以用来预测面条色泽。色泽L*均匀性、煮面10 min后鲜重和灰分含量分别与面条硬度、弹性和光滑性评分呈负相关关系,影响显著。理化和烹调特性中的色泽a*值对面条感官总分影响最显著。     

生物活性低聚半乳糖牛乳的理化及感官特性分析

对生物活性低聚半乳糖牛乳进行了理化以及感官特性分析.采用高效阴离子交换色谱-脉冲安培检测器对活性乳中的低聚半乳糖进行定性、定量分析.结果表明,活性乳中生成低聚半乳糖质量分数为0.881 g/100 g,转化率为17.0%.经过乳成分检测,活性乳中含乳脂肪0.10%,蛋白质3.26%,非脂乳固体8.68%,乳糖4.42%(均为质量分数),质量分数皆符合灭茵乳国家标准.经色差仪检测,该活性乳与原料牛乳的明度、红绿色差有显著性差异(p<0.05),在黄蓝颜色及总色差上有极显著差异(p<0.01).活性乳呈微黄色、外观均一,感官评定结果显示,活性乳有较强的奶香味,甜度较高,与原料乳的滋味、气味及组织状态没有显著性差异,而色泽及甜度则差异极显著(P<0.01).     

不同品种籼米生产的鲜湿米粉理化特性与感官品质

采用湖南省各地区广泛种植的50种籼米原料来生产鲜湿米粉,对鲜湿米粉的理化特性及其感官品质进行研究.通过二者相关性和回归分析,为生产鲜湿米粉的品质评价和专用稻种的选择提供理论依据.研究结果发现,理化性质中的透射比、熟断条率、碘蓝值、吐浆值与鲜湿米粉的组织形态、口感、色泽等重要感官品质呈极显著或显著相关,当碘蓝值中等(0.1～0.3)、透射比高(＞0.85)、熟断条率低(＜10%)以及吐浆值低(＜5%)时,鲜湿米粉的感官评分相对最高.碘蓝值、透射比、熟断条率和吐浆值这些理化特性指标能够较好地反映出鲜湿米粉的感官特性,可以用来评价鲜湿米粉的品质.同时,稻米品种对鲜湿米粉的品质有极显著影响,其中T优167、早熟213和中嘉早17品种的籼米制作的鲜湿米粉的品质最好.     

菊粉梨汁的研制及其功能评价

以梨为原料、菊粉为配料研制了一种高膳食纤维梨汁饮品—菊粉梨汁。通过单因素实验、Box-Behnken（BB）实验和正交实验,结合感官评定的方法优化了菊粉梨汁的最佳配方。采用DPPH法和重量法分别评价、测定了菊粉梨汁的清除自由基能力和膳食纤维的含量。结果表明,果胶酶添加量为0.05%时可获得较高出汁率。菊粉梨汁的最佳配方为梨汁40%,蔗糖添加量为7.0%,柠檬酸为0.15%,菊粉为2.99%,复合稳定剂为CMC-Na 0.15%,黄原胶0.10%,海藻酸钠0.15%。该菊粉梨汁对自由基清除的IC50为2.64%,膳食纤维含量为4.98%,其抗氧化性和膳食纤维含量均高于不添加菊粉的对照组,说明通过菊粉添加可有效提高果汁饮品中膳食纤维含量和抗氧化性。      

Detection of fruit juice adulteration in apple and pear juice

A method has been developed to detect the adulteration of pear juice with apples and apple juice with pears. In different varieties of apples and pears and in several commercial juices the flavonoids were examined by HPLC with respect to their quality and quantity. The chalcones phloretin glucoside and phloretin xyloglucoside are typical compounds found in apples (detection limit 7 ng). They are suitable indicators for detecting adulteration of pear juice with apples. Isohamnetin glucoside cannot be detected in apples (detection limit 10 ng), but can be used to detect pears in apple juice. The extract or juice was purified with the aid of a polyamide column. The evaporated eluate of methanol was analysed by HPLC (gradient: acetonitrile/1% acetic acid). An RP-18 column and a UV-detector were used. Additionally, the UV spectra of the compounds indicating an adulteration were recorded by a diode array detector.     

Chemical compositional characterization of eight pear cultivars grown in China

The sugar, organic acid, amino acid and fatty acid compounds of eight commercial pear cultivars were identified and quantified using high-performance liquid chromatography (HPLC) equipped with RI and UV detectors and gas-chromatography (GC) equipped with FID detector. The mineral composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The results showed great quantitative differences in the composition of the pear cultivars. Fructose was the dominant sugar in the eight pear varieties, followed by glucose and sucrose, while malic acid was the principal organic acid. The C16:0, C18:0, C18:1, C18:2 and C18:3 fatty acids were clearly the most abundant fatty acids, and the C18 family comprised more than 70% of the total fatty acids content. Asparagine and serine were the principal amino acids. Potassium is the most abundant mineral, followed by magnesium and calcium. The results provide important information on how to make the best use of pear cultivars investigated for different uses, which is of significance for both technological research and processing practice.     

新鲜荔枝汁营养成分分析

对新鲜荔枝汁主要营养成分进行分析,发现荔枝汁含糖量161.4g/L,其中98%为还原糖,所含的有机酸主要是柠檬酸、酒石酸、苹果酸、乙酸等,氨基酸含量136.44mg/100mL,共含有17种氨基酸,其中7种为人体必需氨基酸,营养价值高。     

Maturity and ripening effects on chemical and sensory properties of apple juice

The effects of harvest maturity and ripening on the chemical composition and sensory characteristics of ‘McIntosh’ and ‘Spartan’ apple juice were evaluated. Juice was extracted from fruit harvested at seven weekly intervals beginning 3–4 weeks before commercial harvest and from fruit held in air storage (1°C) for 1 to 3 months. Internal ethylene concentration and starch index were used as maturity indices. Principal component analysis of juice data (pH. titratable acidity, organic acids, soluble solids, sugars, phenols, turbidity, and Hunterlab colour) showed a distinctive maturity effect on the characteristics of juice extracted from fruit immediately after harvest or after storage. Triangle testing showed aroma and flavour differences in both ‘McIntosh’ and ‘Spartan’ to be first discernable when ethylene was first detected (internal ethylene concentration ≥ 0.1 μl litre^?1) and starch hydrolysis evident (starch index 3.0–5.0 for ‘McIntosh’, 1.5–3.0 for ‘Spartan’), or after 2–3 months of air storage. Sensory profiling of fruity aroma, total aroma, fruit flavour by mouth, sweetness, and sourness in the juices showed increased fruitiness and sweetness and decreased sourness with advancing maturity.     

Evaluation of physical and chemical characteristics of newly evolved wheat cultivars

Evaluation of quality characteristics of wheat provides significant feedback to breeders for selection/evolution of the most suitable varieties. Seven advanced wheat cultivars and two commercial varieties were studied for 11 physicochemical characteristics. These cultivars showed significant differences for all parameters except ash content, which showed no significant variation. Test weight ranged between 75.6 kg hl^?1 (NRL‐2005) and 80.5 kg hl^?1 (NRL‐2017). Kernel weight and volume were highest (4.0 g and 3.2 ml) for NRL‐9822 and lowest (3.3 g and 2.6 ml) for NRL‐2005. Biological yield was highest (14 040 kg ha^?1) for NRL‐9822 and lowest (12 380 kg ha^?1) for Takbeer variety. Grain yield varied between 4717 kg ha^?1 (NRL‐01‐7) and 4042 kg ha^?1 (NRL‐9736), non‐grain biomass between 9708 and 8083 kg ha^?1, protein yield between 614.3 and 480.8 kg ha^?1 and harvest index between 34.8 and 30.8%. Moisture content ranged from 7.46 to 9.07%. Gluten and protein contents were highest (39.69 and 13.81%) in NRL‐9736 and lowest (29.78 and 12.70%) in NRL‐9822. Test weight was positively correlated with kernel weight and volume and negatively associated with moisture, protein and gluten contents. Protein and gluten contents had a negative association with kernel weight and volume. Gluten content had a highly positive correlation with protein content. Grain yield was positively correlated with biological yield. Protein yield had a positive relationship with biological and grain yields and a negative association with harvest index. Copyright © 2005 Society of Chemical Industry