A promising natural purple batter system with antioxidant activity for vacuum fried breaded shrimp

Abstract

This study aims to develop a batter system with natural purple and functional quality for vacuum fried breaded shrimp. Purple sweet potato flour (PSPF), soy protein isolate (SPI), and xanthan gum were used as coating materials. The effect of the ratio of SPI and xanthan gum on the rheological properties, coating pick-up, color, moisture content, oil content, texture, anthocyanin content and antioxidant activity were investigated. Compared with the control group, it was observed that the batter system with PSPF, SPI and xanthan gum had better rheological properties. The result showed that a ratio of 2:1 for SPI to xanthan gum had the highest coating pick-up value (49.83%), the more attractive purple (a* = 3.07), less oil content (20.55%) and retained higher anthocyanin content (51.71 mg/100 g). Based on the results of anthocyanin content, vacuum fried shrimps were analyzed for antioxidant activity. In the 2,2-diphenyl-1-picrylhydrazyl (•DPPH), hydroxyl (•OH) radical-scavenging assay test, PSPF vacuum fried shrimps showed high free-radical scavenging activity (60.19% for •DPPH and 35.97% for •OH). Therefore, the batter system with PSPF, SPI and xanthan gum is a promising coating material, which is widely used for vacuum fried breaded products, such as pork chop, steak, chicken nuggets and fish fingers.

Keywords:
vacuum frying; purple batter system; breaded shrimp; rheological properties; anthocyanin content; antioxidant activity