基于超快速气相电子鼻研究不同类型UHT牛奶的挥发性风味特征

采用超快速气相电子鼻对超高温灭菌（ultra high temperature，UHT）全脂、低脂和脱脂牛奶共36 种样品的挥发性风味成分进行定性、定量分析，并结合主成分分析和多层感知器神经网络，对UHT牛奶的香气特征进行分类预测。结果表明，UHT牛奶中含有29 种共同的挥发性风味成分，主要为丙酮、正丁醇和δ-癸内酯等，其中丙酮含量最高，癸醛含量最低。异丁醇、乙偶姻、1-戊醇、E-3-己烯醛和癸醛只在UHT全脂牛奶中存在；3-甲基庚烷、2,6-二甲基吡嗪、E-2-壬烯-1-醇是UHT低脂牛奶的特有成分；α-蒎烯、5-甲基糠醛、癸酸仅在UHT脱脂牛奶中被检出。UHT牛奶主要香气特征体现为蔬菜味、奶油味、草香味、水果味及麦芽味。其中蔬菜味、奶油味、麦芽味在UHT全脂牛奶中分布最广泛；水果味在UHT低脂牛奶中分布最广泛；青草味在UHT脱脂牛奶中分布最广泛。主成分分析显示不同品牌UHT牛奶之间存在显著差异；多层感知器神经网络对UHT牛奶种类的预测准确率高达98.6%。     

Effect of green tea catechins on physical stability and sensory quality of lactose-reduced UHT milk during storage for one year

Ultra-high temperature (UHT) processed lactose-reduced milk containing added green tea extract (GTE) at two concentrations (0.1% and 0.25%) was stored at 22 ± 2 °C for one year. The effect of GTE addition on physical stability, protein binding, and sensory quality was evaluated. Sedimentation in skim milk and creaming of full fat milk were inhibited by addition of GTE. The formation of Maillard-related flavour compounds was inhibited during storage as determined by dynamic headspace GC–MS. Using Western blot analysis, milk proteins were found to be highly conjugated to polyphenols. Addition of GTE before UHT treatment resulted in increased bitterness and astringency in UHT milk and this remained during storage. Even though GTE addition improved the physical stability and inhibited Maillard reactions in the milk, the taste and flavour contribution from GTE was dominating throughout storage, and alternative sources of polyphenols should be explored for increasing shelf-life stability of long-life milk.     

基于Arrhenius模型预测无乳糖超高温乳的货架期

采用电子眼、电子鼻、电子舌等感官评价技术,结合货架期加速实验(ASLT)的阿伦尼乌斯公式(Arrhenius)模型,建立无乳糖超高温灭菌乳(UHT乳)的货架期预测模型。将无乳糖UHT乳分别贮存于37、27、4℃下,以色泽、气味、滋味为主要指标,在不同的贮存温度下,综合分析无乳糖UHT乳品质与贮存时间之间的变化,并应用Arrhenius公式建立货架期模型。结果表明:37、27℃下贮存的无乳糖UHT乳色泽的发生显著性变化(P<0.05)的时间为24、33 d;苦味发生显著性变化(P<0.05)的时间为24、27 d;而贮存60 d气味无显著性变化(P>0.05)。4℃下贮存60 d的无乳糖UHT乳色泽、气味、滋味均无显著性差异(P>0.05)。以苦味为指标,利用Arrhenius公式拟合的货架期模型为:t=0.109×e^-5.1882。选取37、27℃验证模型准确性,与实际货架期之间的误差分别为9.5%、12.5%,误差较小。用此公式计算4℃下无乳糖UHT乳货架期为71 d。因此,以感官指标为依据建立货架期预测模型可预测无乳糖UHT乳的货架期。     

Rheological properties,ginsenosides contents,sensory evaluations of Korean red ginseng extracts

Red ginseng extracts have gained popularity due to their positive impact on health. The objective of this study was to identify the rheological properties, ginsenosides contents and sensory characteristics of six different commercial red ginseng extracts in Korea. Ginseng extracts demonstrated different shear‐thinning flow behaviour (n = 0.59–0.78) with a consistency index (K = 46.77–105.78 Pa sⁿ), which meant they had different viscosity. The amount of ginsenosides and total solid contents were highly correlated (r = 0.954). Six significant attributes (ginseng, angelica, bitterness, ginger flavour and astringency) were identified and can be used as sensory parameters for the determination of the product quality. Hedonic levels of the product were assessed by a group of ninety‐five consumers in their 20 s (n = 32) and over 30 (n = 63). Cluster analysis revealed that consumer acceptance was divided into two major clusters for those that preferred strong (n = 43) and weak (n = 42) ginseng characteristics in the extract.     

Short communication: Variation in the composition and properties of Swedish raw milk for ultra-high-temperature processing

The composition and properties of raw milk are of great importance for the quality and shelf life of the final dairy product, especially in products with a long shelf life [e.g., ultra-high-temperature (UHT)-treated milk]. The objective of this study was to investigate the compositional variation in raw milk samples before processing at the dairy plant. Moreover, we wanted to investigate the effect of the UHT process on this variation (i.e., if the same variation could be observed in the corresponding UHT milk). The quality traits analyzed included detailed milk composition, counts of total and psychrotrophic bacteria, proteolytic activity, and color, as well as predictive measures of stability (i.e., ethanol stability and heat coagulating time). Samples of raw milk and the corresponding produced UHT milk were collected and analyzed on a monthly basis during 1 yr. Principal component analysis was used to identify months showing similarities and differences with respect to total variation. In contrast to previous studies, we observed only small variations between months and no clear effect of season for the raw milk. For the UHT milk, July and the winter months (December, January, and February) tended to separate from the other months. Quality traits showing significant variation were only to some extent identical in raw milk and UHT-processed milk. A better understanding of the natural variation in raw milk quality will provide opportunities to improve the shelf life of UHT-treated milk products.     

Sensory Quality of Functional Beverages: Bitterness Perception and Bitter Masking of Olive Leaf Extract Fortified Fruit Smoothies

Abstract: Olive leaf extract (OLE) contains high amounts of oleuropein and hydroxytyrosol. The antioxidant capacity of these polyphenols makes OLE a promising ingredient for functional food. OLE causes very strong bitterness perception and can therefore only be formulated in low concentrations. In this research, bitter detection and recognition thresholds of OLE-fortified fruit smoothies were determined by a trained sensory panel (n = 11). Masking of the OLE's bitter taste was investigated with addition of sodium cyclamate, sodium chloride, and sucrose by means of a standardized ranking method and a scale test. Detection (5.78 mg/100 g) and recognition thresholds (8.05 mg/100 g) of OLE polyphenols confirmed the low formulation limits when bitterness was not masked by other substances. At higher polyphenol levels of 20 mg/100 g, sodium cyclamate and sucrose were able to reduce bitter taste perception by 39.9% and 24.9%, respectively, whereas sodium chloride could not effectively mask bitterness. Practical Application: Development of functional food poses new challenges for the food industry. A major problem in this field is the high bitterness of natural polyphenol-containing extracts with potential health benefits. This research was conducted to understand the sensory impact of olive leaf extract (OLE), a novel food ingredient with very bitter taste. In product development, the data of this research can be considered for formulation limits and the general sensory quality of OLE-fortified food and beverages.     

Sensory characteristics of human milk: Association between mothers' diet and milk for bitter taste

It is unknown how consumption of bitter foods and beverages in the maternal diet influences sensory properties of fresh human milk. The aims of this study were (1) to determine the sensory characteristics of fresh human fore and hind milk, (2) to establish relationships between sensory properties and composition of fresh human milk, and (3) to assess the relationship between bitterness of the maternal diet and human milk. Twenty-two lactating mothers generated sensory terms to describe perception of their milk and received training on sensory attribute intensity rating. Mothers kept a 24-h food diary followed by a sensory self-assessment of their fore and hind milks. The odor of human fresh milk was described as neutral, creamy, and sweet, taste as sweet and bitter, and mouthfeel as thin, watery, smooth, and fatty. Sweetness was equivalent to 1.53 g of sucrose/100 mL and was not significantly different between fore and hind milk. Fore milk was significantly less creamy, less fatty, thinner, more watery, and lower in vanilla flavor intensity than hind milk. Carbohydrate content of human milk was positively correlated with sweetness and glutamic acid content with umami. The bitterness of the diet consumed 24 h before lactation was moderately positively correlated with bitterness of fore milk, but not hind milk. We conclude that the consumption of bitter foods may influence the bitterness of human fore milk, which may be another way for?breastfed children to learn to accept bitter vegetables and, hence, develop healthier food preferences.     

GCMS、GCOMS结合感官评价分析牦牛奶粉风味组分

本实验以乙醚为萃取溶剂,采用同时蒸馏萃取法（SDE）提取牦牛奶粉中挥发性组分,结合气相色谱-质谱联用技术（GC-MS）和气相色谱-嗅闻-质谱（GC-O-MS）,对牦牛奶粉中风味物质定性定量分析。通过8名感官评价人员对牦牛奶粉进行感官评价,奶粉样品色泽良好,其中奶香味、奶油味和甜味比较浓郁,有微弱咸味和煮熟味,无苦味、酸味及涩味。GC-MS和GC-O-MS共同检测出21种挥发性物质,包括酮类8种,醛类3种,烯烃类3种,醇类2种,杂环类2种,酚类2种,醚类1种。其中醇和酮类物质含量较高,分别为46.85μg/m L和38.63μg/m L。实验表明,GC-MS、GC-O-MS结合感官评价分析牦牛奶粉中的风味组分的方法是较为准确和高效的。      

UHT纯牛奶消费喜好和关键感官特性的关联分析

以14种市场上不同类型超高温（Ultra-high temperature,UHT）纯牛奶为研究对象,采用9点喜好标度、适合项勾选法（Check-All-That-Apply,CATA）和恰好标度,同时结合偏最小二乘回归分析（PLS）分析不同类型UHT奶消费喜好和关键感官特性接受性差异。研究表明：不同类型UHT奶的整体喜好值范围为4.07~6.25,脱脂奶和部分全脂奶的喜好值最低（<5）,全脂和低脂奶的整体喜好差异不显著（p>0.05）。不同类型UHT奶的乳香、甜味、余味、浓稠和爽滑5个关键感官特性接受性上存在显著差异（p<0.05）,通过PLS回归模型筛选出导致消费喜好差异的7个关键感官特性接受性指标,分别为余味、乳香、甜味、浓稠、爽滑（-）、甜味（-）和乳香（-）。甜味和乳香偏弱以及爽滑度不够是分别导致低脂奶和部分全脂奶样品整体喜好偏低的关键感官特性。相关研究旨在为后期UHT纯牛奶消费喜好和产品感官品质研究提供基础理论和数据参考。     

香菇鲜味低钠盐的配方研究及其智能感官分析

目的 优化香菇鲜味低钠盐产品配方,并对其进行智能感官分析。方法 以感官评分为评价指标,通过单因素试验和正交试验对香菇鲜味低钠盐的产品配方进行研究,并应用电子鼻与电子舌对最佳配方的气味和滋味特点与普通精制盐、普通低钠盐进行对比分析。结果 香菇鲜味低钠盐最佳配方为:香菇提取物添加量为0.8‰、白砂糖添加量为1.0‰、L-苹果酸添加量为0.5‰、5’-呈味核苷酸二钠添加量为0.4‰;感官评分值可达96.2分;含有较为丰富的含硫有机化合物及芳香族化合物。电子舌测定的苦味、涩味、苦味回味和涩味回味均在无味点以下且均低于普通低钠盐,鲜味和丰富性显著高于其他两款食盐,咸味高于普通低钠盐,与精制盐无显著差异。结论 优化后的产品保留了食盐的咸味且鲜味突出,风味及口感俱佳,明显优于普通精制盐和低钠盐。     

可可粉末香精的感官分析及其在食品中的应用

研究了可可粉末香精作为可可粉的代替物在食品中的应用,通过感官分析从整体喜好度、香气、巧克力风味、苦味、口感五个方面对样品进行评价,并通过SPSS软件对所得数据进行方差分析.实验得出可可粉末香精能替代可可粉,同时在感官分析中没有明显差异.试验得出可可粉末香精在不同食品中可可粉的代替量,在水中溶解0.02％可可粉末香精可替代0.25％可可粉：在奶粉和牛奶中0.04％的可可粉末香精可替代0.25％的可可粉;在冰淇淋中0.05％的可可粉末香精可替代0.5％的可可粉;在饼干夹心中0.15％的可可粉末香精可代替2.5％的可可粉末.通过实验可以看出可可粉末香精在不影响产品感官品质的同时能大大降低可可粉的用量,降低产品的成本.     

高压脉冲电场对牛奶中风味物质的影响

本实验采用SPME-GC-MS 联用的方法,对鲜牛乳、UHT 灭菌牛奶和高压脉冲电场(PEF)处理(35kV/cm,400μS,200Hz)牛乳的风味成分进行分析。从鲜牛乳、UHT 灭菌乳和PEF 处理乳分别鉴定出19、17、18 种主要挥发性化合物。通过对不同处理方式牛乳挥发性风味成分的比较研究,PEF 处理较UHT 处理对牛乳中风味物质影响较小,且产生较少的与蒸煮味相关的含硫化合物。     

人参饮料加工工艺研究

以人参为原料制作人参饮料。以人参皂甙含量为指标,确定了人参的最佳浸提工艺,并通过正交试验得到人参饮料配方。试验结果表明,人参最佳浸提条件为:浸提温度90℃、浸提时间60min、料液比1∶10;人参饮料的最佳配方为:人参浸提汁10%、白砂糖8%、食盐0.05%。以此工艺条件和配方制得的人参饮料滋味柔和,具有人参饮料特有的风味和色泽。     

菊粉、大豆拉丝蛋白及茶叶提取物在发酵香肠中的应用

以菊粉部分代替肥肉,以大豆拉丝蛋白部分代替瘦肉,在肉馅中添加茶叶提取物,通过质构仪结合感官评定,对产品主料配方进行研究,确定产品的主料配方为:猪瘦肉56%、猪肥肉10%、菊粉10%、大豆拉丝蛋白9%、茶叶提取物15%。用少量的菊粉及大豆拉丝蛋白分别部分替代肥肉及瘦肉,添加少量茶叶提取物生产发酵香肠可行,在此条件下,产品色泽均匀,茶香味与发酵芳香风味协调,口感润滑,质地紧密。     

Effects of Docosahexaenoic Acid Content in Triacylglycerol on Human Taste Perception

ABSTRACT: To elucidate the contribution of docosahexaenoic acid (DHA) in triacylglycerol to tuna oil specific taste effects, suppression of bitterness and enhancement of umami, we conducted sensory analysis employing an oil-in-water emulsion prepared with taste substances and the oils differed in the DHA content. The tuna oil specific taste effects were linearly dependent on DHA content. The increase of DHA in oil also linearly enhanced umami and flavor (continuity and richness) of synthetic tuna extract. These results indicate that DHA, a major fatty acid of tuna oil, greatly contributes to tuna oil specific effects on basic tastes and flavor.     

多菌种发酵人参酒及皂苷转化的分析

采用甜酒曲、红曲以及蓝靛果酵母,以正交试验法确定发酵工艺,借助氢谱(1H-NMR)、紫外(UV)及高效液相色谱(HPLC)等手段分析人参皂苷变化。结果表明：蓝靛果酵母与甜酒曲对酒质影响显著,3类菌的最佳配比为每100g糯米加入甜酒曲0.3g进行糖化、然后于每100mL糖化液中加入红曲13g、人参根粉25g、蓝靛果酵母液7mL;发酵前后,HPLC图中峰增加6个、消失3个,UV在280～320nm区域增加了11个吸收峰、1H-NMR在9段化学位移内存在相对积分发生明显变化,表明发酵人参酒的皂苷发生了转化。