Abstract: Changes in moisture content, water activity (aw ), color and 2-thiobarbituric acid (TBA) value of milk powder packaged with different packaging materials i.e., aluminum foil bags (polyethylene terephthalate/ polyamide/aluminum foil/ polyethylene (PET/PA/AL/PE)), cup-shaped capsule 1 (polypropylene/ethylenevinyl alcohol copolymer/polypropylene (PP/ EVOH/PP) and cup-shaped capsule 2 (PP) were examined during 12 weeks of accelerated storage in under constant temperature (37 or 42 ℃) and humidity (75%) conditions. The results showed that moisture content and aw in milk powder packaged with aluminum foil bags remained relatively stable during accelerated storage under the same conditions and color difference (ΔE) and TBA value increased with storage time. For milk powder packaged with cup-shaped capsules, all parameters (moisture content, aw, L*, a*, b*, ΔE and TBA values) continuously increased, and cup-shaped capsule 1 resulted in smaller increased in these parameters than did cup-shaped capsule 2. In conclusion, aluminum foil packaging was the best method for preserving milk powder, followed by cup-shaped capsule 1, and cup-shaped capsule 2 was the least effective method.

Key words: milk powder; packaging; stability; 2-thiobarbituric acid value (TBA); color evaluation

摘要： 研究不同包装材料(铝箔袋:聚酯(polyethylene terephthalate,PET)/聚酰胺(polyamide,PA)/铝箔(aluminum foil,AL)/聚乙烯(polyethylene,PE);杯装胶囊1:聚丙烯(polypropylene,PP)/乙烯-乙烯醇共聚物(ethylenevinyl alcohol copolymer,EVOH) /PP;杯装胶囊2:PP包装的乳粉,在恒温恒湿培养箱内37℃或42℃、相对湿度75％的条件下加速贮存12周,乳粉水分含量、水分活度(water activity,aw)、色泽及硫代巴比妥酸(thiobarbituric acid,TBA)值的变化.结果表明:相同条件下,铝箔袋包装的乳粉水分含量、aw在加速贮存实验过程中处于相对稳定,色差△E和TBA值随着加速时间的延长而增高;胶囊包装的乳粉在加速贮存实验期所有指标(水分含量、aw、亮度值￡*、红度值a*、黄度值b*、△E及TBA值)都持续性增高,且胶囊1乳粉各指标的变化幅度小于胶囊2.结论:铝箔袋包装对乳粉的保护性最好,胶囊1次之,胶囊2最差,开发胶囊乳粉优选胶囊1材质.

关键词: 乳粉；包装；稳定性；硫代巴比妥酸值；色泽评价