Effects of hot air drying process on lipid quality of whelks Neptunea arthritica cumingi Crosse and Neverita didyma

Abstract

Whelks Neptunea arthritica cumingi Crosse and Neverita didyma were processed by hot air drying and changes of thei lipids and the mechanism involved were evaluated by analyzing peroxide value, thiobarbituric acid-reactive substances, total oxidation value, fatty acid composition, activities of lipases and lipoxygenase (LOX), as well as contents of triacylglycerol (TAG), free fatty acid (FFA), phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The processing significantly decreased the contents of PC, PE and TAG but increased the content of FFA. The presence of acid lipase and phospholipase in whelk tissues and their activity preservation during processing suggest that the enzymes may help hydrolyze lipids. By contrast, the reduction of PC, PE and TAG was more pronounced than the increase in FFA in whelk tissues upon processing, indicating the oxidative degradation of FFA. LOX may play a role in lipid oxidation due to the stability of the starting components during processing.

Keywords: Hot air drying; Hydrolysis; Lipid quality; Oxidation; Whelk.

Fig. 1

Changes of POV (a), TBARS (b) and TOTOX (c) of whelks Neptunea arthritica cumingi Crosse and Neverita didyma upon different treatments. Sample 1 represents fresh whelk, sample 2 represents 5 min-boiled whelk, sample 3 represents 10 min-boiled whelk, sample 4 represents 50 °C-dried whelk after 5 min-boiled, sample 5 represents 70 °C-dried whelk after 5 min-boiled, sample 6 represents 50 °C-dried whelk after 10 min-boiled and sample 7 represents 70 °C-dried whelk after 10 min-boiled. Values of different groups with different lower case letters (a–d) and upper case letters (A–F) are significantly different at p < 0.05

Fig. 2

Changes of the contents of TAG (a) and FFA (b) in whelks Neptunea arthritica cumingi Crosse and Neverita didyma (on a dry basis) upon different treatments. Sample 1 represents fresh whelk, sample 2 represents 5 min-boiled whelk, sample 3 represents 10 min-boiled whelk, sample 4 represents 50 °C-dried whelk after 5 min-boiled, sample 5 represents 70 °C-dried whelk after 5 min-boiled, sample 6 represents 50 °C-dried whelk after 10 min-boiled and sample 7 represents 70 °C-dried whelk after 10 min-boiled. Values of different groups with different lower case letters (a–f) and upper case letters (A–F) are significantly different at p < 0.05

Fig. 3

Changes of the contents of PC (a) and PE (b) in whelks Neptunea arthritica cumingi Crosse and Neverita didyma (on a dry basis) upon different treatments. Sample 1 represents fresh whelk, sample 2 represents 5 min-boiled whelk, sample 3 represents 10 min-boiled whelk, sample 4 represents 50 °C-dried whelk after 5 min-boiled, sample 5 represents 70 °C-dried whelk after 5 min-boiled, sample 6 represents 50 °C-dried whelk after 10 min-boiled and sample 7 represents 70 °C-dried whelk after 10 min-boiled. Values of different groups with different lower case letters (a–d) and upper case letters (A–C) are significantly different at p < 0.05

Fig. 4

Changes of the activities for acid lapse (a), phospholipase (b) and LOX (c) in whelks Neptunea arthritica cumingi Crosse and Neverita didyma (on a dry basis) upon different treatments. Sample 1 represents fresh whelk, sample 2 represents 5 min-boiled whelk, sample 3 represents 10 min-boiled whelk, sample 4 represents 50 °C-dried whelk after 5 min-boiled, sample 5 represents 70 °C-dried whelk after 5 min-boiled, sample 6 represents 50 °C-dried whelk after 10 min-boiled and sample 7 represents 70 °C-dried whelk after 10 min-boiled. Values of different groups with different lower case letters (a–f), upper case letters (A–F) and roman numeral (I–V) are significantly different at p < 0.05