酸处理调控鲜切马铃薯质构特性机制的研究

Controlling texture, flavour, and nutritional qualities of potato staple foods though food processing has attracted much attention in recent years with the development of national strategy for potato staple food. Unlike the lucubrated study on browning inhibition, the study on structural characteristics improvement of fresh-cut potato is scant, and the development of fresh-cut potato processing industry is further restricted, too. Research about the effect of acid pre-treatment on the cell components (starch and pectinase) and cell wall characteristics (structure and chemical composition) of potato is considered in this study to elucidate the mechanism involved in textural characteristics improvement of fresh-cut potato after cooking. The main research contents are as follows: ① the correlation study between potato cell (cell components and cell wall structure) and textural characteristics of fresh-cut potato; ② the mechanism study on improvement of textural characteristics of fresh-cut potato by acid pre-treatment. This study can reveal the scientific principle of acid pre-treatment on improving the textural characteristics of fresh-cut potato, provide a new sight in establishing quality evaluation system for fresh-cut potato, and is valuable in the development of technique for improving structural characteristics of fresh-cut potato after cooking.

随着国家马铃薯主食化战略的实施，加工环节在调控马铃薯食品质构、风味及营养方面的研究近年来得到极大重视。其中，鲜切马铃薯作为一种原薯加工主食产品，与其褐变抑制得到深入研究不同，其热加工品质调控技术研究极为薄弱，进一步限制了鲜切马铃薯加工产业的发展。本项目在研究酸处理对马铃薯细胞成分（淀粉、果胶甲酯酶）及细胞壁特性（结构及化学组成）影响的基础之上，重点以阐明酸处理调控鲜切马铃薯质构特性的机制为目标，主要开展如下研究：①鲜切马铃薯（粉质及脆质）的细胞壁结构、细胞组成和质构特性间相互关系研究；②酸处理改善马铃薯质构特性的机制研究。该研究将揭示酸处理提升鲜切马铃薯质构特性的科学原理；能为建立鲜切马铃薯热加工品质的评价体系提供新的视角；同时对提升鲜切马铃薯的热加工品质具有重要的参考价值。

(1)马铃薯的硬度在热加工之后会显著降低，这大大限制了马铃薯的产品开发。而如何提升马铃薯的热加工质构特性目前仍然缺少研究。本文中，通过乳酸和氯化钙联合处理鲜切马铃薯，使其热加工后的硬度从288g提高到了2342g。通过对细胞壁的观察、不同果胶成分分子量分布、中性糖含量及酶活（果胶酶和果胶甲酯酶）的分析解析了这一现象的机制。最终，明确果胶胶凝化和果胶酶活性的变化是提升马铃薯热加工质构特性的靶点。.(2)鲜切马铃薯片是火锅的宠儿。但是，马铃薯鲜切片在蒸煮过程中渗漏大量的淀粉使得锅底容易增稠而降低传热。醋酸和乳酸作为前处理试剂作用鲜切马铃薯片，使得其蒸煮后的淀粉渗透速率显著下降。此外，处理后马铃薯片的营养及短期（7日）贮藏特性得到了验证。发现1.0-1.5% (v/v)酸处理的马铃薯片显著降低了蒸煮损失和淀粉消化率。同时，维生素C和质构特性也减缓了损失。这使得马铃薯片的氧化率降低，且累计总酚含量得到提升。.(3)以马铃薯为主要原料，添加辣椒、花椒等调味辅料，通过响应曲面优化试验，以感官评分值为评价指标优化即食风味马铃薯片加工工艺。结果表明，泡椒风味马铃薯片的最佳制作工艺参数为：马铃薯切片厚度2.5 mm、真空处理时间40 min、蒸煮时间165 s，感官评分达到92.0；麻辣风味马铃薯片的最佳制作工艺参数为：马铃薯切片厚度1.7 mm、真空处理时间40 min、蒸煮时间120 s，感官评分达到93.0。在此优化条件下制得的两种即食风味马铃薯片感官指标、微生物指标合格，口感香脆，品质优良。改善了传统马铃薯薯片的加工工艺，为企业的工业化生产提供一定的理论依据。包装袋透光率对泡椒鲜切马铃薯片储藏品质有显著影响，氧气透过量和水蒸气透过量较低的不透明耐高温PET/铝箔/PE袋能有效抑制泡椒鲜切马铃薯片的褐变，减缓L*值的降低，保持硬度、弹性和咀嚼性水平，抑制微生物的生长，泡椒鲜切马铃薯片储藏42 d后，其品质完好，口感佳，与其他两种包装袋相比，显著延长了产品货架期。