煎炸猪油掺杂比例对猪油低场核磁共振弛豫特性及脂肪酸组成的影响

研究不同比例煎炸猪油掺入食用猪油样品的低场核磁共振（low field-nuclear magnetic resonance,LF-NMR）弛豫特性及脂肪酸组成,并分析了二者间的相关性。结果表明：随着煎炸猪油掺杂比例的增加,猪油样品的T21峰起始时间显著减小（P＜0.05）、峰面积比例S21和S22/S23线性增加（R2＞0.968 1）,S22的增长规律符合二项式关系（R2=0.988 6）,峰面积比例S23、单组分弛豫时间T2W、不饱和脂肪酸C18∶1＋C18∶2的含量及不饱和脂肪酸含量/饱和脂肪酸含量（相对不饱和度）均线性降低（R2＞0.956 2）,而T22峰起始时间呈阶梯下降趋势,T23峰起始时间与掺杂比例间的规律性不明显。此外,样品的棕榈油酸C16∶1、棕榈酸C16∶0、亚油酸C18∶2、硬脂酸C18∶0、C18∶1+C18∶2含量及相对不饱和度与LF-NMR弛豫特性S21、T21、S22、T23、T2W存在良好的相关性（R2为0.942～0.995）。研究表明可通过样品的LF-NMR弛豫特性有效反映脂肪酸组成和含量的变化,并对煎炸猪油掺杂比例进行预测。     

冷藏基围虾水分迁移和品质变化的相关性

以基围虾为对象,测定其在4、0 ℃贮藏过程中菌落总数、pH值、总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、K值、水分含量等理化指标的变化,利用低场核磁共振技术分析基围虾肌肉中水分迁移规律,进而研究品质变化与水分迁移的相关性。结果表明：在贮藏过程中,菌落总数、TVB-N含量均随贮藏时间的延长而呈增大趋势,pH值先降低后升高,水分含量呈降低趋势;横向弛豫时间T2测定结果表明,随着贮藏时间的延长,结合水（T21）含量无明显变化,不易流动水（T22）含量逐渐降低,自由水（T23）含量逐渐升高;通过分析横向驰豫时间T2与各理化指标之间的相关性表明,T22、T23与多个理化指标具有相关性。因此,运用低场核磁共振技术检测基围虾贮藏期间的品质变化具有可行性。     

加热温度对热诱导乳化凝胶形成过程中~1H分布状态及迁移规律的影响

应用低场核磁共振技术(Low-Field NMR)研究肉糜体系中1H分布状态及迁移规律,并结合肉糜水分含量、离心失水率、颜色、p H变化分析加热温度对肉糜体系保水性及乳化凝胶品质的影响。结果表明,随着加热温度的上升,肉糜的水分含量逐渐降低,离心损失增加。同时,不易流动水的弛豫时间T22缩短,其所占的峰面积比也降低,而自由水的弛豫时间T23所占的峰面积比逐渐增加。相关性分析结果显示,弛豫时间T22的峰面积比与水分含量(r=0.755)呈极显著正相关(P0.01),与弛豫时间T23的峰面积比(r=-0.990)、离心损失率(r=-0.798)、肉糜的亮度(L*)值(r=-0.597)和p H(r=-0.573)均呈极显著负相关(P0.01)。这说明热诱导乳化凝胶形成过程中,蛋白质对结合水的束缚逐渐增强,部分结合水转化成自由水,乳化凝胶的保水性降低,同时伴有肉糜亮度和p H值升高。     

无花果热风干燥过程中水分变化及其品质研究

为探究不同温度热风干燥过程中水分含量变化情况及对无花果品质的影响,该研究采用不同温度热风干燥（50、60、70、80℃）对无花果进行干燥处理后,运用低场核磁共振（low-field nuclear magnetic resonance,LF-NMR）技术检测各温度干燥过程中无花果的水分迁移规律,采用色差计测定不同干燥温度的无花果色泽变化,并对其总酚含量及抗氧化活性进行考察。结果表明,随干燥温度的升高,无花果的干燥速率显著提高,达到平衡的时间明显缩短。低场核磁共振信号显示,随干燥时间的延长,核磁共振横向弛豫T2峰向左移动,说明随着干燥时间的延长无花果中水分自由度降低。T2峰横向弛豫时间、峰面积（A）与水分比相关性分析结果显示,干燥过程中无花果的水分比（moisture ratio,MR）与T21、T23的横向弛豫时间以及A23、A总呈显著相关。低场核磁共振成像（low-field magnetic resonance imaging,LF-MRI）图谱显示,新鲜无花果内部水分分布较为均匀,随干燥时间的延长,水分由内向外周扩散。不同温度烘干样品的品质分析显示低温烘干（50℃或60℃）能更好地保持无花果的色泽,而高温烘干（80℃）样品中多酚类成分含量最高,其抗氧化活性最好。以上研究表明低场核磁共振技术可用于热风干燥过程中无花果水分含量、分布及其状态变化的无损检测。     

基于低场核磁研究稻谷吸附/解吸过程水分分布变化

基于低场核磁技术,对粳稻谷、糙米、去胚糙米、精米进行数据采集,确定了低场核磁不同反演峰的真实含义,并且研究了粳稻谷的吸附和解吸过程中水分迁移变化规律,对吸附解吸过程不同结合程度水分的低场核磁反演峰进行了分析,得到了粳稻谷在吸附和解吸过程水分迁移变化规律。研究表明,稻谷、糙米、去胚糙米和精米的T21、T22峰峰面积差距不大,精米的T23峰峰面积几乎可以忽略。在解吸过程中,粳稻谷T21峰的峰面积和峰顶点时间与稻谷解吸质量变化有很高的拟合度,T22峰的面积与稻谷质量变化成正相关,T23峰面积变化微弱;在吸附过程中,T21峰与稻谷吸附质量变化有较高的拟合度,T22峰没有明显的时间规律性,T23峰峰面积变化不大;解吸过程中Page方程为y=e-0.1611x0.601 0(r~2=0.993 5)。     

生鲜猪持水性的核磁共振研究

用低场核磁共振仪检测了宰后猪肉样品水分分布的变化情况.研究发现:肉中有三个明显的水分群,分别时应的横向弛豫时间是T21、T22、T23,其中T23积分面积与滴水损失之间的相关系数为-0.860.实验数据表明,LF-NMR的横向弛豫时间是研究持水性和水分分布的一种非常有效的方法.     

掺杂猪油比例对花生油脂肪酸组成及LF-NMR弛豫特性的影响

研究掺杂不同比例猪油对花生油脂肪酸组成及低场核磁弛豫特性的影响,并分析了二者的相关性。结果表明：随猪油比例的增加,掺杂样品中饱和脂肪酸含量显著增加,掺杂参数（adulteration parameter,AP）减小;单组分弛豫时间（T2W）线性减小;掺杂比例大于30%时,T21显著下降后一直保持不变,T22变化不显著;S21、S22分别呈线性增加和减小趋势,且在掺杂比例大于50%后变化显著。掺杂猪油的样品在主成分分布图上呈从右上角到左下角的分布趋势,当掺杂比例大于20%,掺杂油样与花生油样品可明显区分。样品的低场核磁特性主成分综合得分（F值）与AP值间具有较好的相关性（R2=0.969）,研究表明可通过样品的低场核磁弛豫特性预测脂肪酸组成的变化情况,从而快速判别其品质。     

低场核磁共振技术检测煎炸油品质

应用低场核磁共振技术对无对象煎炸大豆油油样进行检测,通过对多组分T2弛豫图谱以及峰面积比例S21和单组份弛豫时间T2w分析,煎炸4h后图谱中10ms左右出现明显特征小峰,且S21和T2w与煎炸时间、酸价、黏度、吸光度和极性组分含量呈现良好的规律性,相关系数在0.941～0.997之间,说明可以利用低场核磁共振检测的S21和T2W有效反映煎炸油的品质变化。但与过氧化值之间无明显规律性。结果可为后期煎炸油的低场核磁共振技术快速检测提供基础。     

猪油煎炸过程中理化性质与低场核磁共振弛豫特性的相关性分析

以猪油为研究对象,以薯条为煎炸原料,研究不同物料比条件下,猪油理化性质与低场核磁共振（lowfield nuclear magnetic resonance,LF-NMR）弛豫特性的变化规律,并分析各理化指标与LF-NMR弛豫特性之间的相关性。结果表明：随着煎炸时间的延长,猪油的总极性化合物（total polar compounds,TPC）含量呈指数增长（R2＞0.992）,共轭二烯（K232）和共轭三烯（K270）呈线性增长（R2＞0.952）,过氧化值（peroxide value,PV）呈先增后减趋势,峰面积比例S21的升高规律符合二项式关系（R2＞0.974）,单组分弛豫时间T2W的降低规律符合二项式关系（R2＞0.901）,而峰面积比例S22、S23、峰起始时间T21、T22和T23则规律性不明显。随着物料比的增加,油样的TPC含量和K270显著增大,T2W显著减小。回归分析表明,TPC、K232、K270、PV与S21、T2W能够建立良好的相关模型（R2＞0.948）,模型验证合理可靠,说明可以通过猪油的LF-NMR弛豫特性快速、有效预测相关理化指标的变化。     

不同冷藏条件下金枪鱼的水分迁移与脂肪酸变化的相关性

为了研究金枪鱼在冷藏期间的水分迁移与脂肪酸变化的相关性,采用低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)技术分析金枪鱼肉组织中水分变化规律。横向弛豫时间T2分析结果表明:随着贮藏时间的延长,表征不易流动水的T21逐渐降低,表征自由水的T22逐渐升高。理化指标测定结果显示:随着贮藏时间延长,pH值先下降后上升,硫代巴比妥酸值呈上升趋势,而aw、水分含量不断下降,金枪鱼肉品质下降。相关性分析结果表明:表征强结合水的T2b与C18:0、二十碳五烯酸含量呈显著负相关(P0.05),T21与二十二碳六烯酸含量呈极显著正相关(P0.01),T22与C18:0、C18:1n9c含量分别呈极显著(P0.01)和显著(P0.05)正相关。因此,可考虑运用LF-NMR技术检测金枪鱼在冷藏期间检测脂肪酸含量的变化,从而表征其品质劣变的程度。     

带鱼冷藏过程中品质变化与水分迁移的相关性

为了研究带鱼在冷藏期间的品质变化与水分迁移的关系,利用低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)技术分析组织中水分变化规律。横向弛豫时间T_2的结果表明:随着贮藏时间的延长,不易流动水(T_(22))逐渐降低,自由水(T_(23))逐渐升高,肌原纤维内的水向外移动而大量流失,肌肉的持水能力下降、肉质逐渐劣化。这与传统理化指标的研究结果一致,且相关性分析表明,T_(22)、T_(23)与水分含量、蒸煮损失率等指标极显著相关(P0.01),与感官评分、持水力、硫代巴比妥酸值显著相关(P0.05)。因此,可考虑运用LF-NMR技术检测带鱼在冷藏期间的品质变化。     

Stabilised cocosoy beverage: physicochemical and sensory properties

Beverages formulated from extracts of blanched coconut meat and germinated soybean were compared for their proximate composition to achieve the recommendations for vegetable milks. The stability of cocosoy beverage treated with varying levels (0.2–1.0%, v/v) of a 20% gum acacia solution was determined visually and objectively after 5 days of quiescent refrigerated storage. Cocosoy beverage (50:50, v/v coconut milk to soy milk) had 3.51% protein, 3.53% fat and 5.17% carbohydrate. Similarly, it contained 13.0, 5.2, 14.7, 18.7, 0.5 and 0.3 g kg⁻¹ K, Na, Ca, Mg, Fe and P, respectively. Compared with whole coconut milk and reconstituted whole milk powder, cocosoy beverage had significantly higher total solid contents and viscosity but lower pH and buffer index. A total solids top to bottom (T/B) ratio and protein (T/B ratio) of 0.97 and 1.0, respectively, corresponding to a separation index of 1.0, was obtained in cocosoy beverage stabilised with 1.0% gum acacia. Cocosoy beverage stabilised with 1.0% (v/v) gum acacia was rated significantly higher for all the tested sensory attributes. Cocosoy beverage, similar to whole coconut milk, had high contents of glucose and sucrose, a moderate content of fructose, low content of raffinose and no trace of stachyose. Copyright © 2006 Society of Chemical Industry     

速溶杂粮固体饮料研制

以小米、黑米、黑小麦、黑燕麦、黑花生、黑豆和黑芝麻为主要原料,开发一种速溶杂粮固体饮料。通过单因素和正交试验确定速溶杂粮固体饮料最佳配方,并对其理化性质进行分析。结果表明,杂粮饮料最佳配方为小米、黑米、黑小麦、黑燕麦、黑花生、黑豆和黑芝麻按照7︰5︰2︰2︰2︰1︰1比例组成复配杂粮粉,植脂末添加量5.00%,二氧化硅添加量0.93%,糖添加量16.67%;制得的杂粮固体饮料的水分、蛋白质和脂肪含量分别为3.45%,20.75%和7.0%,溶解性28.9%,润湿性284 s,休止角42°。产品速溶性好,口感细腻,甜度适中。     

脂肪添加种类和比例对鱼豆腐品质特性的影响

为研究脂肪添加种类和比例对鱼豆腐品质特性的影响,分别制备添加10%、20%、30%的乳化猪背膘 （emulsified pig backfat,EPB）或乳化鸡皮（emulsified chicken skin,ECS）的6 组鱼豆腐,并测定其营养成分、色 泽、蒸煮损失、质构特性、脂肪酸组成及横向弛豫时间（T2）。结果表明：随着脂肪添加比例的增加,鱼豆腐中的 蛋白质和水分含量明显降低,脂肪含量、脂肪酸总量、亮度值（L*）和白度值（W）有升高趋势;添加30%脂肪鱼 豆腐的蒸煮损失率最大,弹性和T22峰值最低;与添加ECS的鱼豆腐相比,添加EPB鱼豆腐的脂肪含量、L*、W、T22 较高,而蛋白质含量、水分含量、蒸煮损失率及不饱和脂肪酸含量较低。从营养特性、脂肪酸组成、蒸煮损失率、 色泽和凝胶特性等各项指标综合分析,在鱼豆腐的实际生产中,添加20%的脂肪比较合适,将EPB和ECS混合添加 的效果更好,不仅能有效改善鱼豆腐的脂肪酸及营养组成,得到的鱼豆腐成品口感和色泽俱佳,且成品具有较好的 质构特性。     

Whey protein hydrolysate: Functional properties,nutritional quality and utilization in beverage formulation

The objective of the study was to analyze the functional and nutritional properties of enzymatically hydrolyzed whey protein concentrate (WPC) and to formulate a beverage mix. WPC hydrolysates were produced using fungal protease and papain, at time intervals of 20, 40 and 60 min and were analyzed for proximate composition and functional properties. A beverage was formulated with hydrolyzed WPC, skim milk powder, cocoa, liquid glucose, sugar and vegetable fat and analyzed for physicochemical properties, sensory attributes and keeping quality. Results revealed that the protein content of WPC was 75.6% and decreased slightly on enzyme treatment (69.6%). The water absorption capacity of WPC was 10 ml/100 g and increased in enzyme treated samples from 16 to 34 ml/100 g with increase in the time of hydrolysis. Emulsion capacity (45 ml of oil/g of control WPC) showed a decreasing trend with increasing time of hydrolysis. Enzyme treatment slightly increased the foam capacity in three samples but lowered foam stability in all. The gel filtration pattern of enzyme treated samples showed an increase in low molecular weight fractions. The amino acid profile showed higher content of methionine in samples treated with enzymes, compared to the control. The in vitro protein digestibility of untreated WPC was 25% and increased in all treated samples to varying degrees (69–70%). Formulated beverage had 52% protein, 10% fat and 6.6% ash. There were no significant differences in the sensory attributes of formulated and commercial beverage. The formulated beverage could be stored well in a PET container for 30 days.     

明胶-蔗糖/NaCl体系的LF-NMR弛豫特性及主成分分析

论文主要研究了不同浓度的蔗糖及Na Cl对明胶凝胶体系低场核磁共振(LF-NMR)弛豫特性的影响,并应用主成分分析(PCA)对弛豫特性及其与明胶凝冻强度的相关性进行了分析。结果表明,随蔗糖浓度的增加,明胶-蔗糖凝胶体系的结合水弛豫时间(T21)延长,自由水弛豫时间(T22)和单组份弛豫时间(T2w)缩短,结合水比例(S21%)增大,而自由水比例(S22%)相对减少;而随Na Cl浓度的增加,明胶-Na Cl凝胶体系的T21、T22和T2w均相对延长,S21%和S22%则分别增大和减少。两种凝胶体系之间及其与相应的溶剂之间在PCA得分图上均有明显的区分,且明胶-蔗糖/Na Cl凝胶体系的凝冻强度与其LF-NMR主成分综合得分间存在良好的相关性。研究表明,LF-NMR技术可以有效反映明胶-蔗糖/Na Cl凝胶体系中水分状态及其相应比例的变化,且可反映其凝冻强度的变化,这可为明胶应用于食品生产加工提供一定的指导作用。     

我国市售饮料中游离糖含量研究

目的 了解我国市售饮料中游离糖及其单体的含量,为游离糖摄入及其风险评估提供基础数据,为制定完善相关政策提供科学依据.方法 根据我国饮料行业产销量并结合地理分布,2015年采集9类饮料样品共计708份;根据美国分析化学家协会(AOAC)2000.17方法,以高效离子色谱-脉冲安培检测法测定其中的单糖和二糖(葡萄糖、果糖、...     

Effect of pasteurization and fat,protein, casein to serum protein ratio,and milk temperature on milk beverage color and viscosity

Our goal was to determine the effect of pasteurization-homogenization, fat and protein concentration, proportion of milk protein that is casein and serum protein, and temperature on sensory and instrumental measures of viscosity and color of milk-based beverages. A second goal was to use instrumental measures of whiteness and yellowness to predict sensory measures of whiteness and yellowness. A complete balanced 3 factor (fat, true protein, and casein as a percentage of true protein) design was applied with 3 levels of fat (0.2, 1.0 and 2.0%), 4 levels of true protein (3.00, 3.67, 4.34, and 5.00%) within each fat level, and 5 levels of casein as a percentage of true protein (CN%TP; 5, 25, 50, 75, and 80%) within each protein level for beverage formulation. Instrumental color and viscosity, and visual sensory color analyses were done on each beverage formulation. For unpasteurized beverages across 3 fat levels (0.2, 1, and 2%), changes in CN%TP had the largest effect on L values, sensory whiteness, opacity, color intensity, and yellowness, whereas changes in fat concentration had a stronger influence on a and b* values. Increasing CN%TP from 5 to 80% increased L values, sensory whiteness, and opacity, and decreased sensory color intensity and yellowness. The a and b* values increased with increasing fat concentration. For unpasteurized milk protein beverages within each fat level, variation in CN%TP dominated the changes in L values, sensory whiteness, and opacity, and decreased a and b* values, sensory color intensity, and yellowness. The effect of heat (pasteurization and homogenization) and its interaction terms had the second largest effect on color of milk protein beverages with respect to instrumental color data and sensory appearance attributes. Heat increased L values, sensory whiteness, and opacity, and decreased a and b* values, sensory color intensity, and yellowness. Increases in temperature decreased instrumental viscosity and changes in protein concentration and CN%TP had a greater effect on instrument viscosity data within each temperature (4, 20, and 50°C) than fat. Sensory perception of yellowness was not highly correlated with b* values. Multiple linear regressions of L, a, and b* values produced more robust predictions for both sensory whiteness and yellowness than simple linear regression with L and b* values alone, and may be a useful instrumental approach for quality control of sensory whiteness and yellowness of milk protein beverages.     

Assessment of a mobile phone for use as a spectroscopic analytical tool for foods and beverages

A mobile phone was used to perform optical analyses of foods and beverages. The phone’s screen served as illumination source and front view camera recorded images. Reflected intensities were used to discriminate between the different samples analysed by principal component analysis. Samples studied illustrated the technique’s potential analytical capabilities with respect to adulteration and authenticity. Three coloured additives (red, green and blue) in the concentration range 2–10 mg L^?1 in a lemon lime beverage were discriminated. Adulteration by up to 25% water of milk with 3% fat content was detected with an estimated detection limit of about 3% water. Changes occurring on a green onion surface over a 48‐h ageing period at room temperature were monitored. Five different cuts from lamb carcasses weighing 9 and 14 kg were classified by the method. Considerable additional work with regard to sampling, data treatment and quantifying results is necessary before the goal of using the technique as a point‐of‐purchase analytical tool can be realised.