渗透压脱水前处理对芒果冻藏中品质变化的影响

Effects of Osmo-dehydration on Quality Attributes of Mangoes during Frozen Storage

摘要:

本文研究了渗透脱水前处理对芒果冷冻时间和品质的影响，渗透脱水条件是：分别采用不同浓度（30%、40%、50%（m/m））的混合溶液（蔗糖、葡萄糖、果糖质量比为3.6:1:3）作为渗透液、温度30 ℃，时间2 h；冻藏条件为-18 ℃，为期6个月。实验结果表明，与直接冷冻相比，渗透脱水联合冷冻能够缩短6.3~13.8%的芒果冷冻时间。并且，在经过6个月的冻藏后，渗透脱水联合冷冻使得芒果的总色差降低了12.5~36.8%，硬度提高了35.8~65.5%，汁液流失率减少了11.3~44.5%，维生素C含量提高了21.2~134.8%。结果显示，较高浓度的渗透脱水前处理能够较好地保持冻藏芒果的品质，而40%的渗透液浓度是芒果冷冻保藏的最优条件。同时，芒果阴面（较硬）比阳面（较软）更适合于冷冻保藏。随着冻藏时间延长，渗透脱水前处理的冻藏芒果比直接冷冻的芒果品质下降缓慢。本文表明渗透脱水联合冷冻能够提高芒果的冷冻速率和品质。

Abstract:

The effects of osmotic dehydration pretreatment on the freezing time and the quality attributes of frozen mangoes were investigated. Mangoes were dehydrated in mixed osmotic solutions (sucrose: glucose: fructose, 3.6:1:3) at three concentrations (30%, 40%, and 50%, m/m) for 2 h at 30 ℃, and then stored at -18 ℃for six months. The results revealed that the freezing time of the osmo-dehydrofrozen samples was 6.3~13.8% lower than that of the conventional frozen samples. Moreover, osmotic dehydration pretreatment improved the quality attributes of frozen mango in terms of color (total color difference reducing by 12.5~36.8%), hardness (increasing by 35.8~65.5%), drip loss (reducing by 11.3~44.5%) and vitamin C content (increasing by 21.2~134.8%) compared to the untreated ones after six months of frozen storage. Pretreatment with higher solution concentration showed smaller alterations in the quality attributes of samples. Through comprehensive analysis, dehydration in osmotic solution of 40% concentration was considered as the optimum pretreatment condition for frozen storage. In addition, the quality was better maintained in shaded side (firmer) of mangoes than the sun-exposed side (softer). With progression of storage time, mangoes pretreated by osmotic dehydration showed less reduction than the untreated ones. The current study indicates osmotic dehydration enhances both freezing rate and quality attributes of frozen mango.