婴儿配方奶粉中维生素A的稳定性研究

发布时间：2018-08-04 15:14

【摘要】：本文对两种婴儿配方奶粉及主要原料中的维生素A分布情况进行了分析,并且研究了婴儿配方奶粉中维生素A酯类稳定性及其在加工和储藏过程中的稳定性,建立了储藏过程中婴儿配方奶粉中维生素A降解动力学模型。并且借助数学模型讨论了如何合理强化维生素A的问题。所有样品中维生素A的测定均采用国标中的高效液相色谱法。前处理采用皂化处理,在30℃下使用甲醇等度洗脱。该法精密度、回收率和灵敏度较高,适用于婴儿配方奶粉中的维生素A的测定。而维生素A酯类单体的稳定性的研究则采用分光光度法,因维生素A醋酸酯和棕榈酸酯在波长326和324nm下,吸光度与浓度线性关系好。首先,研究了同一类型生产线上的两种不同配方的婴儿配方奶粉及其主要原料中维生素A的宏观分布情况。结果表明,两种配方产品中维生素A的含量存在显著性差异。配方1中维生素A含量为1593.2±32.9IU/100g,配方2为2231.8±58.9IU/100g,配方2产品中维生素A含量明显高于配方1,配方差异是造成含量差异的原因。不同产地的全脂奶粉、生乳、乳清粉中维生素A的含量间均存在显著性差异,维生素A含量范围分别为303.55~610.0IU/100g、570.6~910.0IU/100g、17.4-21.6IU/100g。不同原料对产品中维生素A含量的影响不同,其中全脂奶粉或生乳对产品中维生素A含量有显著性影响,是产品强化维生素A时要考虑的因素；而乳清粉对产品中维生素A含量没有显著性影响,添加时可以不予考虑。其次,研究了维生素A醋酸酯(RA)和维生素A棕榈酸酯(RP)在不同储藏环境下的稳定性及热降解动力学。结果表明,有H2O2和盐酸存在时RA不稳定；且RA、RP均对高温和光敏感；Fe3+和Cu2+引起两种酯类的损失较大,而A13+引起RA的损失较大；在碱、抗氧化剂、防腐剂存在时都较稳定；维生素A酯类在正己烷中比在乙醇中稳定。多数情况下,RP的稳定性高于RA。维生素A酯类的热降解符合一级反应,RA和RP热降解反应的活化能分别为80.59和100.41kJ/mol。再次,通过对浓缩杀菌、喷雾干燥和流化床过程中维生素A的损失进行测定,研究了不同婴儿配方奶粉中维生素A在加工工艺过程的稳定性。结果表明,所有样品在浓缩杀菌、喷雾干燥和流化床过程中维生素A含量均有所减低,但两种配方奶粉中维生素A稳定性存在差异。杀菌浓缩过程中维生素A损失最大,两种配方奶粉的损失率分别为9.58±0.77%和11.6±0.66%。而喷雾及流化床干燥过程中损失较小,损失率分别为4.21±0.85%和4.50±1.15%。整个过程损失率分别为13.34±0.84%和15.59±0.89%,而造成维生素A损失的最主要步骤是杀菌浓缩。但从总体上看,加工过程中损失率变异程度低,损失率稳定,产品中维生素A含量可控且均符合国家标准。最后,对不同储藏条件下两种婴儿配方奶粉中维生素A的稳定性进行了研究。结果表明,温度和时间对维生素A的稳定性影响显著。随着温度的增加,储藏时间的延长,产品中维生素A的损失率都明显增加,但相对来说配方1中维生素A稳定性较高,其脂肪含量较高可能是造成差异的原因。20℃下储藏12个月,维生素A的损失率分别为13.59%和18.87%；而40℃时,损失率分别上升至31.46%和36.62%。产品中维生素A降解符合一级反应,配方1中维生素A降解的活化能为38.39kJ/mol,明显高于配方2(28.73kJ/mol),因此配方1中维生素A更加稳定。另外,通过活化能建立的模型推测出两种配方产品在20℃下理论货架期均超过18个月,而在40℃下理论货架期分别为8月和15个月左右。本文在综合一系列稳定性研究结果的基础上建立起简单有效的数学模型,成功解决了VA添加量的问题。并且对如何提高VA稳定性,减少其损失进行了讨论。
[Abstract]:In this paper, the distribution of vitamin A in two infant formula milk powder and main raw materials was analyzed. The stability of vitamin A esters in infant formula and its stability during processing and storage were studied. A kinetic model of biodegradation of vitamin A in infant formula was established and the mathematical model was used. The problem of how to rationally strengthen vitamin A was discussed. The determination of vitamin A in all samples was determined by high performance liquid chromatography in the national standard. The pretreatment was treated by saponification and eluted with methanol at 30 C. The precision, recovery and sensitivity of the method were high, and the determination of vitamin A in Yu Ying formula milk powder was applicable. The stability of the prime A ester monomer was studied by spectrophotometric method. The linear relationship between the absorbance and the concentration of vitamin A acetate and palmitate at 326 and 324nm was linear.
First, the macro distribution of vitamin A in two different formula milk powder and its main raw materials on the same type of production line was studied. The results showed that there were significant differences in vitamin A content in the two formula products. The content of vitamin A in Formula 1 was 1593.2 + 32.9IU/100g, formula 2 was 2231.8 + 58.9IU/100g, and formula 2 was produced. Vitamin A content in the product was significantly higher than that of Formula 1. The difference in formula was the cause of the difference in content. There were significant differences in vitamin A content among whole milk powder, raw milk and whey powder from different habitats. The content range of vitamin A was 303.55~610.0IU/100g, 570.6~910.0IU/ 100g, and 17.4-21.6IU/100g. of different raw materials on the vitamin in the product. The effect of A content is different, among which full fat milk powder or raw milk has a significant effect on vitamin A content in the product, which is the factor to be considered when the product strengthens vitamin A, and whey powder has no significant influence on vitamin A content in the product, and the addition can not be considered when adding.
Secondly, the stability and thermal degradation kinetics of vitamin A acetate (RA) and vitamin A palmitate (RP) in different storage environments were studied. The results showed that RA was unstable in the presence of H2O2 and hydrochloric acid; and RA, RP were sensitive to high temperature and light; Fe3+ and Cu2+ caused two kinds of esters to cause greater loss, while A13+ caused the greater loss of RA; in alkali, Antioxidants and preservatives are all stable at the time of existence; vitamin A esters are more stable in n-hexane than in ethanol. In most cases, the stability of RP is higher than that of RA. vitamin A esters. The activation energy of RA and RP thermal degradation reaction is 80.59 and 100.41kJ/mol., respectively.
Thirdly, by measuring the loss of vitamin A in the process of concentrated germicidal, spray drying and fluidized bed, the stability of vitamin A in different infant formula milk powder was studied. The results showed that all the samples were reduced in the process of concentrated germicidal, spray drying and fluidized bed, but the content of vitamin A decreased, but two kinds of formula milk were made. There was a difference in the stability of vitamin A in the powder. The loss of vitamin A was the largest in the process of bactericidal concentration. The loss rates of the two formula milk powder were 9.58 + 0.77% and 11.6 + 0.66%., respectively, while the loss was smaller in the spray and fluidized bed drying process. The loss rates were 4.21 + 0.85% and 4.50 + 1.15%., respectively, 13.34 + 0.84% and 15.59 + 15.59, respectively. The most important step for the loss of vitamin A is bactericidal concentration. However, in general, the loss rate is low, the loss rate is stable, and the content of vitamin A in the product is controlled and all in line with the national standard.
Finally, the stability of vitamin A in two infant formula milk formula under different storage conditions was studied. The results showed that the temperature and time had significant influence on the stability of vitamin A. With the increase of temperature, the storage time was prolonged, the loss rate of vitamin A in the product increased obviously, but the stability of vitamin A in Formula 1 was relatively stable. Higher fat content may be the cause of difference at.20 C for 12 months, and the loss rates of vitamin A are 13.59% and 18.87%, respectively. At 40, the loss rate of vitamin A degradation in 31.46% and 36.62%. products conforms to the first order reaction, and the activation energy of vitamin A degradation in Formula 1 is 38.39kJ/mol, obviously higher than that of formula 2. (28.73kJ/mol), therefore, vitamin A in Formula 1 is more stable. Furthermore, through the model established by activation energy, the theoretical shelf life of two formulations is more than 18 months at 20, while the theoretical shelf life at 40 degrees is about 15 months and August, respectively.
In this paper, a simple and effective mathematical model is set up on the basis of a series of results of a series of stability studies. The problem of VA addition is solved successfully. And how to improve the stability of VA and reduce its loss are discussed.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R151

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