Optimization of the protein concentration process from residual peanut oil-cake

M F Gayol,N R Grosso,M C Pramparo,H Fernandez,V Nepote

doi:10.3989/gya.133112

Abstract

The objective of this study was to find the best process conditions for preparing protein concentrate from residual peanut oil-cake (POC). The study was carried out on POC from industrial peanut oil extraction. Different protein extraction and precipitation conditions were used: water/ flour ratio (10:1, 20:1 and 30:1), pH (8, 9 and 10), NaCl concentration (0 and 0.5 M), extraction time (30, 60 and 120 min), temperature (25, 40 and 60 °C), extraction stages (1, 2 and 3), and precipitation pH (4, 4.5 and 5). The extraction and precipitation conditions which showed the highest protein yield were 10:1 water/flour ratio, extraction at pH 9, no NaCl, 2 extraction stages of 30 min at 40 °C and precipitation at pH 4.5. Under these conditions, the peanut protein concentrate (PC) contained 86.22% protein, while the initial POC had 38.04% . POC is an alternative source of protein that can be used for human consumption or animal nutrition. Therefore, it adds value to an industry residue.

Highlights

Peanuts are characterized by high oil and protein content and by low percentages of carbohydrates and ash
There were no significant differences in protein yields among the water/ flour ratios tested
The preparation of peanut protein concentrates was affected by changes in the extraction and precipitation conditions such as temperature, extraction pH, ionic strength, and number of extraction stages, and the precipitation pH

Summary

Introduction

Peanuts are characterized by high oil and protein content and by low percentages of carbohydrates and ash. Peanut seed contains approximately 4752% oil and 25-30% protein (Grosso and Guzmán, 1995). Previous research has shown that peanut seeds are a potential source of food-grade protein for the fortification of food products. Such protein could be concentrated from residual cakes and flours through industrially applicable techniques (Rhee et al, 1972, 1973; Quinn and Beuchat, 1975; Kim et al, 1992; Yu et al, 2007). Peanut protein concentrates were obtained using raw and roasted, fermented and unfermented peanut flours (Yu et al, 2007). These authors obtained peanut protein concentrates with 85% protein versus 50% protein in the defatted peanut flour

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