Survival analysis and cut-off point to estimate the shelf life of refrigerated fish burgers

Abstract The consumption of fish in Brazil is below the world average. In order to change this scenario, considering the high nutritional value of this meat, one of the strategies is to turn fish into a convenient product, such as burgers. Since fish burgers are not yet established in the market, it requires investigation of the shelf life. To that end, survival analysis and cut-off point (COP) methodologies access the perception of consumers and trained panels. Thus, the objective of this study was to estimate the shelf life of grass carp burgers, by means of the survival analysis and cut-off point. A trained sensory panel and consumers evaluated the burgers during a refrigerated storage of 30 days. Simultaneously, the pH and the reactive substances of thiobarbituric acid (TBARS) were evaluated. The TBARS results corroborated rancidity observed both with exponential growth and with correlation coefficients above 0.98. The survival analysis determined the end of the shelf life of the fish burgers after 21 days, with the COP technique indicating 17 days. Both methodologies were efficient in estimating the shelf life of the product analyzed, considering the lower result from COP adequate, since it establishes the value were the acceptability begins to decrease.

摘要
巴西的鱼类消费量低于全球平均水平。鉴于鱼肉具备极高的营养价值，为改善这一现状，可行策略之一是将鱼类加工为即食产品，例如鱼堡。由于目前鱼堡尚未在市场上普及，因此亟需对其货架期开展研究。为此，本研究采用生存分析（survival analysis）与分界点法（cut-off point, COP），分别获取消费者与经过培训的感官评价小组的评价数据。

本研究旨在通过上述两种方法，估算草鱼堡的货架期。研究过程中，经过培训的感官评价小组与消费者对冷藏储存30天内的鱼堡进行了评价；同时，本研究还测定了样品的pH值以及硫代巴比妥酸反应物质（thiobarbituric acid reactive substances, TBARS）含量。TBARS检测结果与感官评定的酸败程度变化趋势一致：其含量呈指数增长，且相关系数均高于0.98。

生存分析结果显示，鱼堡的货架期截止至冷藏储存第21天；而COP法估算的货架期则为17天。两种方法均能有效估算受试产品的货架期，其中COP法所得结果更为严谨合理——因其以消费者可接受性首次出现下降的临界点作为货架期判定依据。