糖液与钙盐组合渗透脱水处理对冻融蓝莓品质的影响

为探究钙盐作为冷冻保护剂与高浓度糖液浸渍组合在常温下进行渗透脱水处理对冷冻蓝莓融化后质地品质的影响。对比以丙酸钙、乳酸钙、氯化钙为代表的3种钙盐冷冻保护剂及质量浓度为0.5、1.5、3.0、5.0 g/mL丙酸钙处理对冻融蓝莓品质的影响。通过观测蓝莓冻融后外观,测定硬度值、弹性、咀嚼性、胶着性、内聚性和回复性品质指标及可溶性果胶、共价结合型果胶和离子结合型果胶的含量。结果表明：添加钙盐结合糖液渗透脱水处理组均可减少蓝莓冻融后皱缩和质地瘫软现象,丙酸钙结合糖液渗透脱水处理组的汁液流失率比对照组降低约25.42%,显著低于（P＜0.05）其他处理组,丙酸钙处理组为较优的钙盐添加种类。对丙酸钙添加浓度进行优化筛选,发现当丙酸钙添加浓度为1.5 g/mL时可显著降低（ P ＜0.05）蓝莓果实的汁液流失和细胞膜透性,冻融后硬度为1.54 N、弹性0.75 mm,可溶性果胶、共价结合型果胶和离子结合型果胶含量分别达到1.03、0.83 和0.68 mg/g,减少蓝莓果实的质地瘫软现象并保持最佳冻融品质。丙酸钙浓度为1.5 g/mL结合渗透脱水技术使冻融蓝莓具有更好的品质,有利于食用和加工。研究结果不仅为解决蓝莓加工行业出现的由于长期冷冻所造成果实质地瘫软问题提供数据基础,还为研发提升果蔬原料冷冻贮藏品质的助冻剂及改性技术提供一定的理论依据。

Effects of osmotic dehydration treatments with sugar solution and calcium on the quality of freeze-thawed blueberry

Calcium salts are commonly used as specific texture-improving additives for preserved fruits and vegetables, pickles, and candied fruits. Osmotic dehydration modified freezing parameters of agro-products, through its high osmotic effect and solute-solvent exchange, effectively preserves the quality of blueberries in terms of color and active substances while facilitating the penetration of additives into fruit and vegetable cells. This study aims to investigate the impact of combining calcium salts as cryoprotectants with high-concentration sugar solution immersion during osmotic dehydration at room temperature on the textural quality of thawed blueberries. Comparison of the effects of three calcium salt cryoprotectants represented by calcium propionate, calcium lactate, and calcium chloride and treatments with concentrations of 0.5, 1.5, 3.0, and 5.0 g/mL calcium propionate on the quality of freeze-thawed blueberries. The effects on freeze-thaw quality were assessed by examining the appearance of blueberries after freeze-thaw, measuring quality indicators such as hardness, elasticity, chewiness, adhesiveness, cohesiveness, and resilience, as well as determining the content of soluble pectin, covalently bound pectin, and ionically bound pectin. The results indicated that the osmotic dehydration treatment with calcium salt and sugar solution effectively reduced wrinkling and texture softening of blueberries after freeze-thaw. The juice loss rate of the calcium propionate and sugar solution-treated group was approximately 25.42% lower than that of the control group, significantly lower than (P < 0.05) the other treatment groups, confirming calcium propionate as the optimal calcium salt additive. Optimization screening of the calcium propionate concentration revealed that at 1.5 g/mL, it significantly reduced juice loss and cell membrane permeability of blueberry fruits after freeze-thaw(P< 0.05) , resulting in a hardness of 1.54 N, elasticity of 0.75 mm, soluble pectin, covalently bound pectin, and ionically bound pectin contents of 1.03 mg/g, 0.83 mg/g and 0.68 mg/g, respectively. This effectively mitigated the softening of blueberry fruits and maintained optimal freeze-thaw quality. The combination of 1.5 g/mL calcium propionate concentration with osmotic dehydration technology enhances the quality of freeze-thawed blueberries, making them suitable for consumption and processing. The results of this experiment showed that 1.5 g/mL calcium propionate combined with 65 g/mL sugar solution could effectively protect the texture parameters of blueberries after freeze-thaw, including hardness, elasticity, chewability, adhesiveness, cohesiveness and resilience, maintain the stability of long chain covalently bound pectin, and inhibit the formation of short chain soluble pectin and loose ion-bound pectin. And minimize the juice loss rate and cell membrane permeability. These results indicate that the osmotic dehydration of 1.5 g/mL calcium propionate combined sugar solution can maximize the effective combination of calcium ions and blueberry pectin, form a "calcium bridge" to inhibit the decomposition of long chain pectin, maintain the integrity of cell wall, reduce the damage of ice crystals to blueberries, and make blueberry fruits have better texture and quality. This study provides technical support and theory to solve the problem of texture softening caused by intolerant freezing of blueberry raw materials, and is conducive to promoting the application of new collaborative freezing technology in frozen storage of processed raw materials. The research findings not only provide a data foundation for addressing the issue of fruit softening caused by long-term freezing in the blueberry processing industry, but also provide a theoretical basis for developing cryoprotectants and modification techniques to enhance the frozen storage quality of fruits and vegetables.