Alkaline Extraction of Protein from Sacha Inchi Oil Press-cake: Effect of pH, Temperature, and Extraction Time

Author(s): Monika Mich, Rong Phaltevy Ung, Sereytevin Chab, Marinich Net, Sela Kong, Reasmey Tan, Manit Say, Yukleav Nat, Chin Ping Tan.

Sacha inchi (Plukenetia volubilis L.) has been used for decades due to its rich in oil and protein. Within the oil extraction, a by-product known as oil press-cake is produced and it is typically wasted even though it contains a high protein content. Therefore, this study aimed to valorize Sacha inchi oil press-cake by extraction of protein using an alkaline extraction method. The effects of the alkaline extraction conditions, including pH (10, 11, and 12), temperature (40, 50, and 60°C), and extraction time (30 and 60 min) were evaluated. The proximate composition of Sacha inchi oil press-cake was also determined using AOAC standard method, while the extracted protein recovery yield was analyzed using Lowry method. As a result, the proximate composition of sacha inchi oil press-cake contained protein (59.5%), total carbohydrates (22.38%), fat (3.59%), ash (5.22%), and moisture (9.32%). The highest protein recovery using alkaline extraction from oil press-cake was 83.57 ± 0.37% with the following conditions: pH 12, 60°C of temperature, and 30 min of extraction time. These results demonstrate that the sacha inchi oil press-cake is a good source of proteins for human nutrition. The conventional alkaline extraction method can be applied to extract protein from the sacha inchi oil press-cake with high efficiency.