Dept. of Agro-Industrial, Food and Environmental Technology, Faculty of Applied Science, Food and Agro-Industrial Research Center, King Mongkut's Univ. of Technology North Bangkok, 1518, Pracharat Road, Bangsue, Bangkok, 10800, Thailand.
Dept. of Food Technology, Thailand Institute of Scientific and Technological Research, Khlong Luang, Pathum Thani, 12120, Thailand.
J Food Sci. 2019 Jul;84(7):1784-1790. doi: 10.1111/1750-3841.14635. Epub 2019 Jun 19.
Freezing and thawing occur during storage, transportation, and retail display, leading to deterioration of frozen shrimp. The objective of this research was to investigate the change in quality of frozen white shrimp treated by lysine and NaHCO after multiple freeze-thaw cycles. Shrimp were soaked in lysine and lysine/NaHCO each at 1% (w/v) frozen in an air-blast freezer at -30 °C, and kept in a chest freezer (-18 ± 2 °C) for a week before they were thawed using tap water before the analysis (freeze-thaw cycle 1). The samples were subjected to five freeze-thaw cycles, which were repeated every week. Qualities of the samples were determined for thawing loss, cutting force, and total volatile basic nitrogen (TVB-N), as well as oxidation stability by using Rancimat. The use of lysine/NaHCO could significantly reduce thawing loss at all freeze-thaw cycles compared to the control and lysine treatment (P < 0.05). Similar results were found with TVB-N and the oxidation stability of the samples. A difference in cutting forces of the shrimp between lysine and lysine/NaHCO treatment was found when the frequency of freeze-thawing was increased to three cycles; it was lower than that in the control at all cycles. Histological study showed that the treatment with lysine/NaHCO led to the swelling of muscle fibers and fewer fragments at five freeze-thaw cycles. The results showed that lysine/NaHCO could effectively retard the quality loss from repeated freeze-thawing during frozen storage. PRACTICAL APPLICATION: Repeated freezing and thawing usually occur during storage, transportation, retail display or in restaurants, and in consumers' kitchens. The temperature at the manufacturing site and during transportation in a tropical country like Thailand is relatively high, and frozen food producers come across quality deterioration resulting from multiple freeze-thaw cycles occurring during transportation and storage. Frozen shrimp producers require research to improve product quality by adding nonphosphate food additives or, if possible, by using natural food ingredients instead of polyphosphate or sodium bicarbonate.
在储存、运输和零售展示过程中会发生冷冻和解冻，导致冷冻虾变质。本研究的目的是研究经过多次冻融循环处理的冷冻白虾的质量变化。将虾浸泡在 1%（w/v）赖氨酸和赖氨酸/碳酸氢钠中，然后在 -30°C 的空气喷射冷冻机中冷冻，并在冰柜中（-18±2°C）保存一周，然后用自来水解冻，再进行分析（第 1 次冻融循环）。样品经过五次冻融循环，每周重复一次。测定样品的解冻损失率、切割力和总挥发性碱性氮（TVB-N）以及通过 Rancimat 测定氧化稳定性。与对照组和赖氨酸处理相比，使用赖氨酸/碳酸氢钠可显著降低所有冻融循环的解冻损失率（P<0.05）。TVB-N 和样品氧化稳定性也得到了类似的结果。随着冻融循环频率增加到三次，发现赖氨酸和赖氨酸/碳酸氢钠处理的虾的切割力之间存在差异；在所有循环中，均低于对照组。组织学研究表明，在五次冻融循环中，赖氨酸/碳酸氢钠处理导致肌肉纤维肿胀和碎片减少。结果表明，赖氨酸/碳酸氢钠可有效延缓冷冻储存过程中反复冻融导致的质量损失。实际应用：在储存、运输、零售展示或在餐厅和消费者厨房中，通常会发生反复冷冻和解冻。在像泰国这样的热带国家，制造现场和运输过程中的温度相对较高，冷冻食品生产商在运输和储存过程中遇到了因多次冻融循环而导致的质量恶化问题。冷冻虾生产商需要研究通过添加非磷酸盐食品添加剂来提高产品质量，或者如果可能的话，使用天然食品成分代替多磷酸盐或碳酸氢钠。
