Using short-wave infrared radiation to improve aqueous enzymatic extraction of peanut oil: Evaluation of peanut cotyledon microstructure and oil quality

Abstract

In this study, the effects of short-wave infrared radiation (SIR) on enzyme-assisted aqueous extraction process (EAEP) of peanut oil (PO) were investigated, including peanuts cotyledon cells mircrostructure and yield as well as quality of extracted PO. GC-flash electronic nose (EN) combined with principal components analysis (PCA) was applied to select conditions for SIR process. The appropriate roasting condition based on the overall flavor was determined as 150 °C for 55 min. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the effects of SIR on cotyledon microstructure. The results demonstrated that SIR damaged the cell microstructure and oil body membrane, and the extraction of oil was facilitated. Accordingly, the oil yield increased significantly by 8.74% compared to that of the control (p < 0.05). Further analysis on the quality properties of PO revealed that the content of polyphenols of oil extracted from SIR roasted peanuts (2.79 ± 0.05 mg GAE/kg) was 62.21% higher than that from the control. It was in consistent with the significantly enhanced oxidation stability of oil in the present study (p < 0.05). Furthermore, the variety and relative content of volatile compounds which contributed to a better overall flavor were greatly increased.

Practical applications: SIR as a mild and efficient roasting method could enhance the oil extraction yield in EAEP and improve the oxidation stability of the extracted oil. With the appropriate pre-roasting of peanuts by SIR, the overall flavor of EAEP extracted peanut oil was improved. Its volatiles pattern was close to that of the commercial hot-pressed PO. It was confirmed that SIR is a novel choice for roasting processing, as well as a potential and available pre-roasting method of peanuts to improve the EAEP technology.

http://ift.tt/2z0CI6t