Department of Food Science and Technology, Faculty of Agro-Industry, Kasetsart University, Bangkok, 10900, Thailand.
J Sci Food Agric. 2014 Jan 30;94(2):189-96. doi: 10.1002/jsfa.6226. Epub 2013 Jun 24.
During storage, frozen fruit may be thawed and refrozen many times before consumption, which may be extremely damaging to the texture of the frozen fruit and reverse the advantage of fast freezing. The effects of freezing and thawing on texture, microstructure and cell wall composition changes in papaya tissues were investigated.
The frozen-thawed papayas had an increase in drip loss and a decrease in firmness with increasing number of freeze-thaw cycles. Light microscopy showed irregular shapes and cell damage in parenchyma cells of frozen-thawed papayas, whereas transmission electron microscopy showed loss of cell wall materials in middle lamella. Moreover, destruction of cell wall was observed after being subjected to five freeze-thaw cycles. These changes related with a significant decrease in alcohol-insoluble solids, Na₂CO₃- and 24% KOH-soluble fractions and an increase in the water-, EDTA- and 4% KOH-soluble fractions. This was due to a decrease in the molecular mass of pectic and hemicellulosic polymers in frozen-thawed papayas using high-performance size-exclusion chromatography.
The freezing and thawing processes caused fine structural damage and cell wall composition changes which contributed to a loss of drip volume and firmness of papaya tissues.
在储存过程中，冷冻水果在食用前可能会解冻和再冷冻多次，这可能会对冷冻水果的质地造成极大的损害，并使快速冷冻的优势反转。本研究旨在探讨冷冻和解冻对木瓜组织的质地、微观结构和细胞壁组成变化的影响。
随着冷冻-解冻循环次数的增加，冷冻-解冻木瓜的汁液损失增加，硬度降低。光镜下可见冷冻-解冻木瓜的薄壁细胞形状不规则，细胞受损，透射电镜下可见中层片的细胞壁物质丢失。此外，在经历五次冷冻-解冻循环后，观察到细胞壁的破坏。这些变化与醇不溶性固体、Na₂CO₃-和 24%KOH 可溶性部分的显著减少以及水、EDTA-和 4%KOH 可溶性部分的增加有关。这是由于冷冻-解冻木瓜中果胶和半纤维素聚合物的分子量下降，使用高效尺寸排阻色谱法。
冷冻和解冻过程导致细微结构损伤和细胞壁组成变化，导致木瓜组织汁液损失和硬度降低。
