Precision of laboratory methods based on protein solubility in quality control of heat treated feedstuffs

Abstract

Some of feedstuffs used as raw materials in feed industry contain anti-nutritional factors that negatively influence their quality. One of them is soybean, which is, prior to oil extraction, referred to as full-fat soybean (FFSB). Anti-nutritional factors in raw FFSB can be destroyed by moderate heating, but both over- and under heat processing limits the availability of soybean amino acids. Among laboratory procedures that are available for assessing the degree of FFSB heat treatment, two methods, i.e. Protein dispersibility index (PDI) and protein solubility in potassium hydroxide (PSKOH), are based on protein solubility, which was claimed to be the most reliable indicator of the degree of FFSB heat treatment. This paper presents the results of an inter-laboratory study conducted to establish precision of the PDI and PSKOH methods by determining their reproducibility limits. Five samples of FFSB were heat-treated at temperatures between 110 and 164 °C and analyzed by six laboratories for PDI and PSKOH. Established reproducibility limit for PDI method of 8.87 index units found in this study appeared to be too wide, indicating a low precision of this method. PSKOH method produced very good reproducibility limit of 8.56% and could be recommended as a preferred method for FFSB quality control in feed laboratories

The protein dispersibility index in the quality control of heat-treated full-fat soybeans: an inter-laboratory study

“…Despite reports (Batal et al, 2000;Dudley-Cash, 2001;Debruyne, 2004;Caprita et al, 2010a;b) on the dominance of the PDI over other methods for monitoring the degree of FFSB heat treatment, the PDI method did not prove that in this study. It is to be noted that the above-mentioned authors obtained their results in single laboratory studies, contrary to the present study, which might be the explanation for the differences in results.…”

“…It has been clearly illustrated that the results of the analysis of the same sample of FFSBs obtained by currently available analytical techniques, vary widely between laboratories, causing uncertainty and confusion among soya processors, feed manufacturers and end-users (Davies, 1998;Palic & Grove, 2004;Palić, 2011). It is, therefore, of the utmost importance that the available laboratory procedures be standardized for determining the degree of soybean processing.…”

Comparative Influence of Dehulling on the Composition, Antioxidative and Functional Properties of Sorrel (<i>Hibiscus sabdariffa</i> L.) Seed

“…The effect of pH on protein solubility of the seed flours was determined by the method of Palić et al [42].…”

Modification of the method for determining protein solubility of heat treated full-fat soybeans using extraction in potassium hydroxide: Inter-laboratory study

“…It has been demonstrated (10,11) that the results of analysis of the same sample of FFSB on the degree of heat treatment obtained by currently available analytical techniques vary widely between laboratories, causing uncertainty among soya processors, feed manufacturers and end-users.…”