Quality Attributes in Shrimp Treated with Polyphosphate after Thawing and Cooking: A Study Using Physicochemical Analytical Methods and Low‐Field 1H NMR

Abstract

AbstractThe effects of polyphosphate on parameters of quality in shrimp (after thawing and cooking) were investigated using physicochemical analytical methods and low‐field nuclear magnetic resonance (LF 1H NMR) spectroscopy. The NMR data were treated by bi‐exponential fitting and compared with the physicochemical data. The physicochemical parameters demonstrated that treatments with different concentrations of sodium tripolyphosphate and different time exposures influenced parameters such as cook loss, moisture, pH, color and texture. These differences were reflected in the transverse relaxation (T2) data. Bi‐exponential fitting of the T2 resulted in the observation of two water populations in all samples, T21 and T22, with relaxation times in the ranges of 24–47 and 63–120 ms, respectively. Pronounced changes in the T21 and T22 relaxation data were observed during the different treatments, with polyphosphate revealing changes in water properties. Good linear correlations were observed between the T2 parameters and physicochemical data.Practical ApplicationsShrimp processing contains various steps, such as freezing and cooking, which can lead to the denaturation or aggregation of proteins. In this context, the use of polyphosphates prior to the freezing of shrimp can improve yields, water‐holding capacity and the sensory attributes of the final product. The fish industry seeks to use polyphosphates in order to optimize production and obtain better quality products. Therefore, studies to identify the ideal phosphate concentration and contact time required for quality production in the frozen shrimp industry are important. Traditional analytical methods for physicochemical measurements are, however, time‐consuming, sample destructive and expensive. Low‐field 1H nuclear magnetic resonance is a rapid, noninvasive method to investigate water mobility within materials and foods. The method showed strong correlations with various physicochemical properties, which are important quality factors during shrimp processing. Moreover, the techniques are fast, reliable and nonsample destructive.