Evaluation of protein quality of Jamaican field crickets (Gryllus assimilis) reared on the dried rapeseed protein

Bc. Yacouba Traore

Master's thesis

Abstract:

Food security is a serious concern particularly for developing countries. To overcome hunger and malnutrition, there is a need for increased research towards finding alternative and cheaper sources of nutrients. Insects have been reported to be good alternative source of proteins. This work therefore aimed to investigate the influence of addition of rapeseed protein into the Jamaican field cricket´s (Gryllus assimilis) diet on their amino acid profiles. The study included five dietary treatments of which four contained rapeseed oil by-products and the fifth was control diet. The chicken feed was used as feed in control group. All the tested feed substrates were based on the modified control diet, in which soybean meal was partially or completely replaced with rapeseed cakes as a food industry by-product. The amino acid profiles of samples were determined by acidic and oxidative hydrolysis of the samples, followed by evaluation using the Amino Acid Analyser with Na-citrate buffers and ninhydrin detection. In comparison with the control group, the crickets fed by substrates containing 17.5 and 35.0 % (25 and 50 % of soybean meal was replaced) of rapeseed cakes had better amino acid composition expressed by essential amino acid index (EAAI), which ranged from 51.73% to 53.38%. The further increase of the rapeseed percentage up to 70 % (75 and 100 % of soybean meal was replaced) conversely caused the decrease of EAAI (from 48.66% to 48.24%). However, the statistic evaluation revealed that the differences in EAAI among the samples were not significant (ɑ = 0.05). The most abundant amino acids in all groups were Glutamic acid followed by Aspartic acid, Alanine and Arginine. Although the levels of individual amino acids slightly varied among the samples, the significant differences were found between the contents of Cysteine, Proline, Tyrosine, Methionine and Threonine. Interestingly, the methionine, which was also determined to be limiting amino acid, content of crickets fed with rapeseed cakes was significantly higher than that of control group. In conclusion, dietary rapeseed cakes, which are greatly available and cheap, could be an interesting alternative to conventional protein sources commonly used for crickets farming. This study revealed that the addition of rapeseed cakes had no significant influence on protein quality expressed by EAAI, even if the soya was completely replaced by rapeseed cakes.

Keywords

edible insects

Language used: English

Date on which the thesis was submitted / produced: 13. 4. 2022

Thesis defence

• Supervisor: Ing. Martin Kulma, Ph.D.

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Master programme:
Food and Nutrition