Sensory Quality of Nonfat Dry Milk after Long-Term Storage

Nonfat dry milk was stored under various conditions to determine the effects of temperature, packaging, atmospheric gases, and form of milk on the sensory quality of the stored product. Nonfat dry milk was significantly affected by storage temperature during long-term storage. Nonfat dry milk held at 32°C for 6 mo began to develop offflavors and by 24 mo was considered unacceptable when evaluated by a trained sensory panel. After 4-yr storage nonfat dry milk samples stored at 21°C were rated unacceptable by the panelists. Storage at 10°C resulted in minimal flavor changes in 52 mo. After 4-yr storage, nonfat dry milk samples stored in Polybags were statistically less acceptable than samples stored in cans. The form of milk (instant or regular) did not affect the length of time nonfat dry milk could be stored. Unacceptability of samples was due to an oxidized/stale flavor.     

Color of Nonfat Fluid Milk as Affected by Fermentation

Nonfat milks inoculated and fermented with exopolysaccharide and non-exopolysaccharide producing cultures were compared to nonfat, 2% milkfat and whole milk with instrumental and sensory color measurements. L-(whiteness) and a- values (red/greeness) for fermented nonfat milks were higher than nonfat milk. No differences in L-, a-, or b- values (yellow/blueness) were found between milks fermented with exopolysaccharide as compared to non-exopolysaccharide producing strains. A trained sensory panel scored edge and center whiteness of fermented milks whiterthan nonfat milk. Milks fermented with exopolysaccharide producing cultures were scored higher than non-exopolysaccharide producing cultures with respect to edge and center whiteness. Fermentation and exopolysaccharide production may increase visual perception of whiteness in milk.     

Vitamin A degradation and light-oxidized flavor defects in milk

To determine the effects of light exposure on vitamin A degradation and on light-oxidized flavor development, samples of whole, reduced fat, and nonfat milk were exposed to fluorescent light (either 1000 or 2000 lx) at time intervals of 2, 4, 8, or 16 h. Measurable vitamin A losses occurred at 2, 4, and 16 h at 2000 lx for nonfat, reduced fat and whole milk, respectively. Moderate light-oxidized flavors were detected after 4 h of light exposure (2000 lx) in the whole and reduced fat milk and after 8 h in nonfat milk. The different types of milk show a significant difference in relative flavor scores. By 16 h at 2000 lx, relative light-oxidized flavor development was lower in nonfat milk than in whole or reduced fat milk. The presence of milk fat appears to protect against vitamin A degradation in fluid products, but adversely affects the flavor quality of milk after exposure to light. In summary, these findings demonstrate that even a brief, moderate light exposure (2 h; 2000 lx) can reduce the nutritional value and flavor quality of fluid milk products.     

奶酒的类型与风味

按发酵和后处理方式,将奶酒分为发酵奶酒、蒸馏奶酒、勾兑奶酒、起泡奶酒和加气起泡奶酒5类。乳清发酵奶酒为浅黄绿色,酒液澄清透明,奶香舒愉,酒香清雅,干型和半干型酸味爽口,甜型和半甜型酸甜适口,后味爽净;蒸馏奶酒清亮透明,具有舒适清雅的奶香和酒香,绵柔醇和,微酸爽口,后味微苦;勾兑奶酒为浊白色,形态均一,具有奶香味,微甜醇和,柔和适口;起泡奶酒兼具酸奶、啤酒和碳酸饮料的风味,营养丰富,外观呈均匀的乳白色,泡沫较细,酸甜适口,爽而不腻,风味独特;加气起泡奶酒色泽浅黄带绿,奶香、酒香、清雅舒愉,酸甜爽口,泡沫较细,有杀口感。     

Soymilk Yogurt: Sensory Evaluation and Chemical Measurement

Soymilk yogurts with fortifiers, 25% fructose (SOYF), evaporated milk (SOYEM) or nonfat dry milk (SOYN), were compared for stachyose concentration; pH; sour, sweet, and beany flavor; and viscosity. Beaniness was reduced significantly compared to unfermented soymilk; SOYF had the lowest panel score. Sour flavor determined by a trained sensory panel on a 10-point intensity scale was 1.8, 7.8, and 8.0 for SOYF, SOYEM, and SOYN, respectively. Mean sensory viscosity scores for these yogurts were 4.8, 7.9, and 9.0, respectively. Sour flavor and viscosity for SOYF were significantly lower than for other yogurts. No relationships between analytical and sensory measurements of flavor were found; however, instrumental viscosity measurements were linearly related to sensory scores.     

基于地域喜好差异的液态乳关键属性优化方法

随着居民消费水平的升级,产品的精细化和个性化成为配方设计新趋势,如何根据不同地区消费者的感官 喜好差异性指导产品配方设计成为新型消费形式下的需求。本研究以不同配方的液态乳产品为对象,开展评价小组 和消费者对风味液态乳产品关键感官属性的感官评价,采用偏相关分析、Penalty分析等多元统计分析方法,多角度 进行风味特征关联性分析,并利用偏好图对分析型感官分析（感官属性强度测量）和情感型感官分析（消费者喜好度 测量）结果进行综合处理,针对不同地区消费人群的喜好差异确定液态乳样品的关键感官属性改进方案。通过配方模 型优化结果可知,上海地区消费者喜欢偏甜的样品,相对的,北京和成都地区消费者偏爱酸甜适中的样品,三个地区 消费者都喜欢乳香味较大、口感细腻的样品,北京地区消费者对稠厚感的要求没有成都和上海地区消费者高。     

Flavor Variability and Flavor Stability of U.S.-Produced Whole Milk Powder

ABSTRACT:  Flavor variability and stability of U.S.-produced whole milk powder (WMP) are important parameters for maximizing quality and global competitiveness of this commodity. This study characterized flavor and flavor stability of domestic WMP. Freshly produced (<1 mo) WMP was collected from 4 U.S. production facilities 5 times over a 1 y period. Each sample was analyzed initially and every 2 mo for sensory profile, volatiles, color, water activity, and moisture through 12 mo storage. Selected volatiles were quantified using solid phase microextraction (SPME) with gas chromatography/mass-spectrometry: dimethyl sulfide, 2-methylbutanal, 3-methylbutanal, hexanal, 2-heptanone, heptanal, 1-octen-3-ol, octanal, 3-octen-2-one, and nonanal. Multiple linear regression with backwards elimination was applied to generate equations to predict grassy and painty flavors based on selected volatiles. All WMP were between 2% and 3% moisture and 0.11 and 0.25 water activity initially. WMP varied in initial flavor profiles with varying levels of cooked, milk fat, and sweet aromatic flavors. During storage, grassy and painty flavors developed while sweet aromatic flavor intensities decreased ( P  < 0.05). Painty and grassy flavors were confirmed by increased levels ( P  < 0.05) of lipid oxidation products such as hexanal, heptanal, and octanal. Hexanal, 2-heptanone, 1-octen-3-ol, and nonanal concentrations were best predictors of grassy flavor ( R ²= 0.38,  P  < 0.0001) while hexanal, 2-methylbutanal, 3-methylbutanal, octanal, and 3-octen-2-one concentrations were best predictors of painty flavor ( R ²= 0.61,  P  < 0.0001). These results provide baseline information to determine specific factors that can be controlled to optimize U.S. WMP flavor and flavor stability.     

Evaluation of Milk Quality in Delivering Sterilized Milk with Soft Tank Transportation System

ABSTRACT:  A new transportation system is proposed recently to improve the defects of liquid transportation by tank trucks. This method is called "soft tank transportation system"; a driver installs a sac-like container (soft tank), which is made from a tarpaulin with high-pressure resistant-waterproof zippers, in a general cargo vehicle. To evaluate the quality of sterilized milk by using the soft tank transportation system, ground and marine transportation for a long distance which took about 36 h from the shipper's loading to the receiver's unloading in a high-temperature summer season (average outside temperature was 33.4 °C) were carried out. Although the difference of milk temperature before and after the delivery varied from −0.7 to +1.4 °C, there was no difference in milk quality (fat, nonfat solids, total dissolved solids, and pH) and no coliform bacteria were detected. It can be evaluated that sterilized milk was carried in keeping good conditions by soft tank transportation system.     

冻藏条件对人乳脂质及挥发性风味物质的影响

以新鲜人乳为对照(0d),设置-18、-60℃和-60℃快速冷冻(-60℃(Q))3种冻藏条件分别冻藏60 d与180 d,通过测定脂质含量、非酯化脂肪酸(non-esterified fatty acids,NEFA)含量、脂质过氧化物(lipid peroxide,LPO)含量、脂肪酸组成、乳脂肪球微观结构及挥发性...     

苹果酵素复合型羊乳的制备及抗氧化活性研究

苹果酵素具有良好的抗氧化活性,为了增加发酵羊乳的抗氧化活性,作者采用苹果酵素与复合发酵剂发酵羊乳,并研究其理化指标及抗氧化活性。依据发酵羊乳的理化指标和感官评价指标,确定苹果酵素添加质量分数、发酵剂类型和发酵剂添加质量分数:苹果酵素添加质量分数4%,B发酵剂添加质量分数为1%时,发酵羊乳蛋白质含量为3.85 g/hg,脂肪含量为3.72 g/hg,非脂乳固体含量为9.28 g/hg,对DPPH自由基清除能力为95.17%,且发酵羊乳凝固状态好,具有发酵羊乳特有的滋味、气味及苹果口味,酸度、甜度合适,为发酵羊乳制品的研究与开发提供理论基础。     

Physical and Sensory Properties of Milk Chocolate Formulated with Anhydrous Milk Fat Fractions

Maximum additions of milk fat that produced temperable milk chocolates were anhydrous milk fat (AMF), middle-melting fraction (MMF) or low-melting fraction (LMF) up to 40 wt % total fat, and high-melting fraction (HMF) up to 35%. The solid fat content (SFC), melting point, melting enthalpy, instrumental and sensory hardness of milk chocolates decreased with increasing milk fat addition. No differences in sensory attributes sweetness, milk powder, chocolate, butter flavor or thickness of melt were observed. Chocolate with 40% MMF or LMF had greater milk flavor than that with 12.2% HMF. Onset of melt correlated (r = 0.96) with melting enthalpy. No differences between types of milk fat (AMF, HMF, MMF, LMF) were observed for any textural attribute assessed.     

Sensory Attributes and Instrumental Analysis Relationships for Strained Processed Carrot Flavor

Regression models relating sensory attributes and composition of tin genotypes of processed strained carrots were developed. Fresh carrot-flavor, aroma, and aftertaste were associated with high total sugar to terpinolene ratios. Sweet taste and sweet aftertaste were associated with high levels of total sugar and high total sugar to terpinolene ratios. Cooked flavor and cooked aftertaste were associated with high terpinolene content. Selection of genotypes with high total sugar to terpinolene ratios should improve strained processed carrot sensory quality.     

Flavor and flavor chemistry differences among milks processed by high-temperature,short-time pasteurization or ultra-pasteurization

Typical high-temperature, short-time (HTST) pasteurization encompasses a lower heat treatment and shorter refrigerated shelf life compared with ultra-pasteurization (UP) achieved by direct steam injection (DSI-UP) or indirect heat (IND-UP). A greater understanding of the effect of different heat treatments on flavor and flavor chemistry of milk is required to characterize, understand, and identify the sources of flavors. The objective of this study was to determine the differences in the flavor and volatile compound profiles of milk subjected to HTST, DSI-UP, or IND-UP using sensory and instrumental techniques. Raw skim and raw standardized 2% fat milks (50 L each) were processed in triplicate and pasteurized at 78°C for 15 s (HTST) or 140°C for 2.3 s by DSI-UP or IND-UP. Milks were cooled and stored at 4°C, then analyzed at d 0, 3, 7, and 14. Sensory attributes were determined using a trained panel, and aroma active compounds were evaluated by solid-phase micro-extraction or stir bar sorptive extraction followed by gas chromatography-mass spectrometry, gas chromatography-olfactometry, and gas chromatography-triple quad mass spectrometry. The UP milks had distinct cooked and sulfur flavors compared with HTST milks. The HTST milks had less diversity in aroma active compounds compared with UP milks. Flavor intensity of all milks decreased by d 14 of storage. Aroma active compound profiles were affected by heat treatment and storage time in both skim and 2% milk. High-impact aroma active compounds were hydrogen sulfide, dimethyl trisulfide, and methional in DSI-UP and 2 and 3-methylbutanal, furfural, 2-heptanone, 2-acetyl-1-pyrroline, 2-aminoacetophenone, benzaldehyde, and dimethyl sulfide in IND-UP. These results provide a foundation knowledge of the effect of heat treatments on flavor development and differences in sensory quality of UP milks.     

牛奶脂肪对不同烘焙程度咖啡感官品质的影响

作者主要研究牛奶脂肪质量分数对不同烘焙程度牛奶咖啡风味的影响及全脂牛奶咖啡中脂肪质量分数的消费者差别阈值。首先,针对浅、中、深3个烘焙程度的咖啡,采用定量描述性分析法评价不同脂肪质量分数牛奶咖啡的风味;其次,采用三点选配法测量全脂牛奶咖啡中脂肪质量分数的差别阈值。结果表明,随着脂肪质量分数降低,咖啡的酸味、苦味、涩味、烟味、煳味、焦香味、生豆味和酸味（鼻前香气）逐渐增强,而甜味、醇厚感、焦糖味和奶香味减弱,这些影响在3种不同烘焙程度咖啡中的变化趋势一致,但随着烘焙程度加深,牛奶脂肪的变化对咖啡风味的影响程度也会上升。进一步通过分析阈值测试结果发现,脂肪质量分数在浅、中、深烘焙咖啡中的差别阈值分别为2.59%、2.45%和2.36%（质量分数）。女性消费者对脂肪的变化更敏感,脂肪质量分数在深焙咖啡中的差别阈值显著低于男性。研究结果可为低脂牛奶咖啡的开发提供理论依据。     

永川豆豉发酵过程中总糖和氨基酸变化与滋味的形成

通过采集传统发酵过程中的永川豆豉样本,对其总糖、还原糖、糖化酶活性、总氨基酸、游离氨基酸构成进行测定。结果表明,在成品豆豉游离氨基酸中,鲜味氨基酸占总游离氨基酸的23.98%,鲜味风味突出。豆豉中甜味氨基酸和还原糖共同构成了其回甜的滋味特点。豆豉中短链脂肪酸和乳酸使其呈现一定的酸味,酚类物质和苦味氨基酸呈现一定的苦味。这些最终决定了永川毛霉型豆豉的特有的咸鲜回甘风味特点。