VC磷酸酯在虾料生产和储存过程中的含量变化研究

利用高效液相色谱法对VC磷酸酯在虾料生产和储存过程中的稳定性,包括VC磷酸酯在混合、超微粉碎、调质、制粒、后熟化和打包等工艺环节和储存15、30、40、50、60、70、80、90 d的含量变化进行了研究。结果表明:不同工艺环节对VC磷酸酯的破坏程度不同,其大小依次为调质后熟化制粒超微混合打包,其中调质过程造成的损失率高达6.86%~8.95%,经过虾料生产过程VC磷酸酯保存率为64.41%~75.93%。VC磷酸酯在虾料储存过程中含量逐渐下降,在3个月的储存期内,保存率在88.36%~91.33%之间,平均每月损失率为2.89%~3.88%。不同厂家生产的VC磷酸酯稳定性存在差异。     

Effects of Processing and Storage on the Folate Content of Spinach and Broccoli

Free and total folate activities (FFA and TFA) in spinach and broccoli were determined at various processing stages. In most cases FFA was significantly lower than TFA (P < 0.05). Steam-blanching resulted in greater TFA retention than water-blanching. Spinach lost 50% of the TFA during canning and another 10% after storage for 3 months. Storage at - 32.2°C of water blanched spinach resulted in 27% TFA loss after 3 months and 17% TFA loss for water-blanched broccoli after 8 months. For spinach and broccoli, 40% and 68%, respectively, of the TFA was in the blanch water but only 1% and 4% TFA, respectively, were in the steam-blanch condensate. When canned, 14% of the TFA in spinach immediately after processing was in the liquid in the can. This amount increased to 18% after 3 months storage.     

Processing and Frozen Storage Effects on the Iron Content of Cod and Mackerel

Processing and subsequent frozen storage affected the iron content of cod (Gadus morhua) and mackerel (Scomber scombrus) muscle tissue. Frame mince was obtained from the bone rack, without the head or viscera remaining, after filleting. Frame mince had significantly higher iron levels than intact fillets with or without skin or fillets that were subsequently minced. Skin-on fillets had more iron than skin-off fillets. Cod frame mince had about 50% heme iron, while mackerel frame mince ranged from 20-64%. Nonheme iron increased during frozen storage due to heme breakdown. Storage above ?14°C was more deleterious to the heme molecule than lower temperatures (?20°C or ?40°C).     

甘薯嫩叶中Vc在加工过程的变化

采用2,4- 二硝基苯肼比色法测定甘薯嫩叶中VC 含量,分析不同贮藏条件及干制、腌制、速冻、烹饪等不同加工方式对VC 含量的影响。结果表明：甘薯嫩茎叶中VC 含量高达26.48mg/100g;甘薯嫩叶采后营养价值随存放时间而递减,低温冷藏和冷冻均能降低其营养损失速度,在6℃下贮藏9d VC 含量为15.96mg/100g;干制及腌制对VC 有较大的损害。甘薯嫩叶的烹饪以适当的高温及尽可能短的时间为佳,在160℃、50s 下VC 残留含量为16.85mg/100g。烹饪过程中适当添加调味料如食醋和蔗糖,可以减少VC 的损失。     

呼和浩特市母乳中维生素含量的研究

于2013年~2014年收集呼和浩特市产后6个月内产妇的母乳样品共53份,测定其维生素含量。结果表明:泌乳期内,母乳中的B族维生素、V_E和V_K无明显变化,组间差异不显著(P0.05);V_C随着泌乳期的延长而升高,V_A随泌乳期的延长呈下降趋势,组间差异显著(P0.05);V_D在所有样品均无法检出。呼和浩特市婴儿的水溶性维生素和脂溶性维生素摄入量均低于中国居民膳食营养素适宜摄入量。泌乳期与V_A含量呈显著负相关(P0.05),与V_C含量呈显著正相关(P0.05);产妇若服用V_(B2)制剂,其母乳中的V_(B2)含量会显著升高(P0.05)。     

Effects of Milk Solids Content on Consumption of Milk

Strong interest continues for higher solids-not-fat standards for whole, lowfat, and skim milk than those currently established by the Food and Drug Administration for milk in interstate commerce. This paper traces the implications of establishing new national fluid milk standards identical to the current high standards in California. The greatest change in product composition implied by the adoption of the California standards would be in lowfat milk, where the solids-not-fat standard would rise from 8.25 to 10.0%. Whole and skim milks’ composition would be less dramatically affected.Fortification costs are estimated at 3¢/.5 gal (1.89 L) for whole milk, about 5¢ for lowfat milks, and about 1.5¢ for skim milk. Retail prices are projected to rise 3 to 5% across the fluid product line. Assuming no change in consumer preferences, fluid milk sales are estimated to drop 1.2 to 5.1% nationwide upon adoption of the California solids standards (the percentage drop dependent upon the responsiveness of consumers to price changes for fluid milk). Total sales of solids-not-fat would increase 21 to 184 million lb (19.52 to 83.46 million kg) annually under higher solids standards, which is not enough to affect significantly the current supply-demand imbalance in the dairy industry.     

高效液相色谱法测定牛奶中的维生素C含量

建立了高效液相色谱法测定牛奶中的维生素C的含量的方法。样品用0.1 mol/L盐酸常温下超声提取,采用高效液相色谱法,维生素C,并与标准系列比较,以保留时间定性,峰面积定量。结果表明,以0.05 mol/L磷酸二氢钾:甲醇(96:4)为流动相,经C18色谱柱分离,回收率为93%~100%,相对标准偏差为0.6%~1.1%。本方法灵敏度高,选择性好,操作简便快捷,具有很好的实用价值。     

Effect of Processing Temperature and Storage Time on Nonfat Dry Milk Proteins

Changes in physicochemical properties of pooled nonfat milk preheated to 63°C (I), 74°C (II), and 85°C (III), before spray-drying were examined. Insoluble material from III contained more protein (particularly at reduced pH) and more coagulated protein-lactose aggregates than either I or II. Soluble material from III was practically depleted of whey proteins which were utilized to form complexes stabilized through disulfide bonds. Milk protein micelles from III were heavier (ca 1 × 10¹¹ g/mole) than either I or II. An unsweetened milk-orange juice blend, which was pasteurized at 63°C for 30 min and stored at 4°C, developed a precipitate which contained more protein and pectin, but less sucrose than the supernatant.     

导致乳粉贮藏加工劣变的主要化学反应和物化因素的研究进展

我国乳制品安全日益受到大众的关注,其中乳粉是焦点之一。目前乳粉贮藏加工中引起质量劣变的因素主要为三类化学反应——脂质氧化,美拉德反应和乳糖结晶,它们之间存在相互作用,但机理尚未明确。文中针对乳粉贮藏加工中的重要化学变化和它们的影响因素、测定方法和相互作用的研究进展进行了综述,并对乳粉贮藏中化学反应的研究方向提出了展望,为进一步从机理上研究乳粉劣变并确保乳粉质量安全提供依据。     

草莓汁加工贮藏过程中维生素C变化规律的研究

初步考察了影响草莓汁加工贮藏过程中维生素C变化的因素。采用正交试验法 ,以加工贮藏过程中维生素C的保存率为考察指标 ,对维生素C的变化进行了初步研究。结果表明 ,试验设计的 4个因素中空气含量对维生素C的变化有显著影响。最佳加工贮藏初步工艺为 :采用热榨加工 ,在 15～ 18℃冷室 ,无氧贮藏方式。这为草莓汁的进一步加工贮藏提供了理论依据     

蛋白含量对搅拌型发酵乳微流变和贮藏特性的影响

蛋白质含量会影响发酵乳特性,进而决定发酵乳品质。采用多频扩散波谱法分析蛋白含量分别为2.4%,2.8%和3.2%时对发酵乳发酵过程中微流变特性影响,分析贮藏期间不同蛋白含量发酵乳的质构特性和稳定性,同时做感官评价。发酵过程微流变分析结果显示,蛋白含量增加形成的乳凝胶具有较高的固-液平衡值和较低的弹性因子,对流动因子虽没有影响,但到达凝胶点的时间较短,缩短了发酵时间。推测蛋白含量的增加加速了酪蛋白颗粒的聚集。发酵终点时蛋白含量2.8%组发酵乳黏度因子最高。贮藏期间,蛋白含量2.8%发酵乳的黏度、稠度、内聚性等均显著高于另外两组(P<0.05),质构状态最佳;蛋白含量2.4%发酵乳的持水力显著低于蛋白含量2.8%组和蛋白含量3.2%组(P<0.05);pH值和滴定酸度随蛋白含量的增加而变大,3组发酵乳pH值和滴定酸度值均匀变化(P>0.05),蛋白含量3.2%组的pH值始终高于另外两组,即蛋白含量越高,滴定酸度越高。感官评价结果显示,蛋白含量2.8%和3.2%的发酵乳各项指标评分接近,总体优于蛋白含量2.4%的。本研究为不同蛋白含量发酵乳的开发提供了试验数据,对多元化发酵乳产品研发具有一定的指导意义。     

气相色谱串联质谱法测定加工工艺对毛豆硒蛋氨酸含量的影响

采用气相色谱串联质谱(GC-MS/MS)方法,研究硒氨基酸衍生物的一级质谱以及二级碰撞离子裂解规律,建立硒蛋氨酸的GC-MS/MS 测定方法,并以此为基础研究在加工和贮藏过程中毛豆中硒蛋氨酸的含量变化。结果显示：在4℃条件下冷藏4 周,以硒蛋氨酸计的硒的损失约为13%;在常温保存过程中,脱水毛豆的硒蛋氨酸降解率最小,而毛豆汁的硒蛋氨酸降解率却显著升高,说明产品的形态对于硒蛋氨酸的影响是非常重要的;毛豆烫漂过程中硒蛋氨酸的损失较小,烫漂210s 硒蛋氨酸的保存率仍然在85% 以上,毛豆脱水工艺中冷冻干燥处理对硒蛋氨酸的保存率最高,其次是真空干燥和热风干燥,硒蛋氨酸的保存率均可达80% 以上,而喷雾干燥因接触空气面积较大,造成有机硒的损失较大,会造成硒蛋氨酸的损失率达到30%～40%。     

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...     

针叶樱桃汁加工贮藏过程中维生素C含量的变化

针叶樱桃中富含维生素C,而维生素C非常不稳定,极易被氧化。研究了不同加工工艺和包装材料对针叶樱桃果汁中维生素C稳定性的影响。结果表明,加工工艺以超高温杀菌后降温再无菌包装处理对针叶樱桃果汁中维生素C的损失最小,保存率达94.56%;包装材料以利乐包材包装的针叶樱桃果汁中维生素C的保存率最高,达76.42%。就贮藏温度而言,并不是温度越低越好,以环境温度15~20℃下维生素C的保存率最高。     

Ultrasonication, Lyophilization, Freezing and Storage Effects on Fat Loss during Mechanical Infusion of Expressed Human Milk

Ultrasonic homogenization was extended to situations where expressed human milk needs to be stored before being administered. We investigated whether the effect of ultrasonication would persist during storage in the frozen or lyophilized form. Recovery of fat was higher in ultrasonicated and frozen milk (stored for both 1 and 4 mo), than in milk stored following ultrasonication and lyophilization. The low fat recovery from stored lyophilized milk was increased by ultrasonicating the milk after storage and reconstitution (instead of prior to storage). Protein recovery was virtually complete with both methods.     

不同贮藏方式对土豆中VC含量的影响

以探讨不同贮藏方式对土豆中VC含量的影响为目的;采用2,6-二氯靛酚滴定法测定不同贮藏方式下的土豆中VC的含量变化;结果是三种贮藏方式下的土豆中VC的含量随着贮藏时间增加而降低,常温贮藏比低温贮藏的土豆VC含量和保存率较高,连续干燥比间歇干燥时维生素保存率高。     

Changes in the Vitamin B-6 Content in Potatoes During Storage

The nature of the repeatedly reported increase of vitamin B-6 in Russet Burbank potatoes stored for 30 days and 9 months was investigated. Potatoes contained pyridoxine, pyridoxamine, pyridoxal phosphate, and a pyridoxine glucoside. While pyridoxamine and pyridoxal phosphate concentrations remained unchanged, there was a sharp increase in pyridoxine glucoside during storage indicating a possible synthesis of vitamin B-6 during storage. In general, good agreement existed between the data generated by microbial analysis and those obtained by the HPLC method.     

牛乳（活性肽）及加工工艺对面包品质的影响

为了增加乳制品的消费量,研究了牛乳和牛乳活性肽添加量及加工工艺对面包品质影响。面包中添加6.0%(m/m)的牛乳或0.014%(m/m)的牛乳活性肽能提高面包的营养价值和弹性,降低面包的硬度,增加面包的比容和感官品质。牛乳面包和牛乳活性肽面包的弹性、硬度和比容分别为0.784、0.931;901.46 g、1466.25 g和6.3 mL/g、6.9 mL/g。虽然面包的品质优于馒头,但用面包的配方加工馒头的工艺也是可行的;面包的丙烯酰胺含量高达92.6±8.4μg/kg,极显著高于蒸烤结合的馒头,而同样配方加工的馒头的丙烯酰胺含量未检出(p0.01),因此在丙烯酰胺含量方面馒头较面包安全。消费者选用那种面包或馒头要根据自身需要,将美味和安全结合起来考量。