Effect of Thermal and Non-Thermal Processing on the Nutritional Composition, Pasting Profile and Protein Secondary Structure of Alfalfa

Abstract

Alfalfa is an unconventional alternative legume and its potentiality for utilization can be improved by processing. In this study, alfalfa seeds were processed by different thermal and non-thermal techniques and evaluated for their physical properties, colour characteristics, nutritional composition, pasting profile and protein secondary structure. The results were analyzed using Principal Component Analysis to elucidate the effect of processing. Colour of the flour was more affected by thermal processing in comparison to non-thermal processing. Nutritional composition of alfalfa flour was significantly affected by germination as compared to other methods and germinated flour showed an increase in the protein content. All the processing treatments resulted in improving the pasting properties except for germination. Particularly, marked improvement in the pasting properties was observed by wet heat processing and soaking. ATR-FTIR exhibited change in the secondary structure of the protein as a result of processing and showed the dominance of intermolecular β-sheets in extrusion, germination and microwave treated flour and formation of anti-parallel β-sheets after dry heat processing. Wet heat processing and soaking treatment can be employed for alfalfa for enhancing its techno-functionality.

Keywords

• alfalfa
• atr-ftir
• pasting
• processing