Application of Aqueous Saline Process to Extract Silkworm Pupae Oil (Bombyx mori): Process Optimization and Composition Analysis

Abstract

Silkworm pupae, a waste product from the silk production industry, can be an alternative source of edible oil, thus reducing the industry’s waste. In the present work, frozen silkworm pupae were used as raw material to extract oil via an aqueous saline process. The Box–Behnken design (BBD) and response surface methodology (RSM) were used to optimize the extraction process. The extraction conditions with the highest oil yield and a low peroxide value were obtained when using a saline solution concentration of 1.7% w/v, a ratio of aqueous liquid to silkworm pupae of 3.3 mL/g, and a 119 min stirring time at the stirring speed of 100 rpm. Under these conditions, silkworm oil with a yield of 3.32%, peroxide values of approximately 1.55 mM, and an acid value of 0.67 mg KOH/g oil was obtained. The extracted oil contained omega-3 acids (α-linolenic acid), which constituted around 25% of the total fatty acids, with approximate cholesterol levels of 109 mg/100 g oil. The amounts of β-carotene and α-tocopherol were approximately 785 and 9434 μg/100 g oil, respectively. Overall, the results demonstrated that oil extracted from silkworm pupae has good quality parameters and thus can be used as a new valuable source of edible lipids.

Facile acid fermentation extraction of silkworm pupae oil and evaluation of its physical and chemical properties for utilization as edible oil

“…The proximate composition of the silkworm pupae is displayed in Table 1 . In this work, the protein content of fresh silkworm pupae was found to be 10.77%, which is slightly lower than the protein content (11.70%) of the previously published report for silkworm pupae [ 19 ], though it was noticed that the protein percent (10.30%) of the edible insect Acheta domesticus was a little bit lower than our finding [ 36 ]. However, it was investigated that the protein content of the eri silkworm was 16 and 24% in pupae cultured on two different types of leaves tapioca and castor, respectively [ 37 ].…”

“…In this study, the fat content of the fresh silkworm pupae was found to be around 6.25%, which is the same as the precedent study [ 19 ], on the other hand, lower than the fat content (8.0–8.6%) in eri silkworm pupae mentioned by Longvah et al [ 37 ]. Studies observed that the different sexes of the silkworm Bombyx mori pupae are responsible for a diverse range of fat content [ 15 ].…”

“…In general, most of the edible insect's pupae and adults are enriched with high protein (more than 10 g proteins/100 g edible portion of fresh weight basis) [ 38 ]. On a dry weight basis, the protein content (49.43%), in this work, was slightly less than previous findings (approximate range: 51–53%) [ 12 , 19 , 37 ].…”

“…Formerly, the utilization of silkworm pupae for extracting oil was performed with differential techniques, for example, mechanical pressing extraction [ 15 ], solvent and supercritical fluid extraction [ 1 , 16 , 17 , 18 ], microwave-assisted gravimetric extraction [ 11 ], and aqueous saline oil extraction [ 19 ]. Some of the mentioned methods involve a lot of labor, time, and solvents, making the extraction process expensive.…”

“…The yield of microwave-assisted extraction is high, but the apparatus price and the used solvent make the extraction expensive. On the other hand, the aqueous saline oil extraction method requires a frozen sample and repeated centrifugation for a long time [ 19 ]. In this regard, acid fermentation with organic acid can be used as a new feasible method with low cost and comparatively high yield for the wide utilization of available silkworm pupae.…”