Colouring the grey areas of insect mass-production to solidify their use as feed, food and biological control agents

Thesis (PhDAgric)--Stellenbosch University, 2019.

ENGLISH ABSTRACT: The mass-production of various insect species for biocontrol methods and as feed and food is becoming common practice and several different rearing facilities have been established across the world. Although insect mass-production facilities have been set in place, the mass- production of insects is still in an infantile stage and research is necessary to optimise these systems. As with conventional intensive livestock production the success of these systems, as well as the costs implicated, can largely be contributed to the nutrition of the animals. Trials were conducted to try and establish the nutrient requirements of selected insect species based on the body composition technique, a method commonly used for conventional livestock. Positive results were obtained for all involved insect species and led to an increase in production output, as well as to a decrease in the cost of production. For mass-produced insects to reach their full potential they need to be tailored for their end use. A study was conducted where larvae were reared on a substrate rich in polyunsaturated fatty acids in attempt to manipulate the fatty acids that they deposited into their biomass, and subsequently to evaluate the effect this had on the production and meat quality parameters of the animals the larvae had been fed to. Promising results were observed as an increase in the omega-3 fatty acids were observed in the larval biomass and the same occurred in the meat of the quails the enriched larvae were fed to. Although, the ratio of polyunsaturated- to saturated fatty acids could not be changed. Insect processing is another field that needs attention and the fractionation of insect biomass into protein, fat and chitin can result in significant increase in the margins made both environmentally and economically. An enzymatic fractionation method was developed that resulted in the isolation of protein, fat, and chitin and greater total recoveries were obtained compared to previous studies. The subsequent quantification of the chitin content of insects has also been a problem in the past and based on chitin isolation from crustaceans, a gravimetrical protocol was developed to address this issue. The resulting protocol led to the most repeatable and accurate estimation of the chitin content of insect larvae to date. Overall, the results obtained from the series of studies were a step in the right direction to solidify the mass-production of insects for biocontrol methods as well as for feed and food purposes.

AFRIKAANSE OPSOMMING: Die grootskaalse produksie van verskillende insekspesies vir die doel van biologiese beheer en as voer en voedsel raak algemene praktyk. ‘n Verskeidenheid produksie eenhede is al reeds gevestig reg oor die wêreld. Alhoewel grootskaalse eenhede alreeds in plek gestel is, is die grootskaalse produksie van insekte nog in ‘n aanvangs fase. Navorsing word benodig sodat hierdie eenhede hul produksie potensiaal kan bereik. Soos in die geval met intensiewe produksie van vee speel voeding ‘n groot rol in die sukses sowel as die koste van die produksie van insekte. Die grootskaalse produksie van verskillende insekspesies vir die doel van biologiese beheer en as voer en voedsel raak algemene praktyk. Proewe was uitgevoer om die nutriënt behoeftes van geselekteerde insek spesies te bepaal met behulp van die heel karkas mael metode, ‘n tegniek wat algemeen in die intensiewe produksie van vee gebruik word. Goeie resultate was aan die orde van die dag vir alle betrokke insek spesies en het ‘n toename in produksie, sowel as ‘n afname in produksie koste, tot gevolg gehad. Indien grootskaalse produksie van insekte sy volle potensiaal wil bereik moet insekte geproduseer word om by die spesifikasies van hul eind gebruik te pas. ‘n Studie was gedoen waar insekte op ‘n substraat ryk aan poli-onversadige vetsure geproduseer was om die insek biomassa dieselfde eienskappe te gee. Dit blyk dat die insekte meer omega-3 vetsure kon neerlê vanaf die verrykde substraat en so ook die diere wat hierdie insekte gevreet het in hulle vleis, alhoewel die verhouding van versadigde- tot onversadigde- vetsure nie gemanupileer kon word nie. Die prosessering van insekte is ‘n veld wat aandag kort en die fraksionering van insekte in hul individuele komponente naamlik proteïen, vet en chitien kan marges verhoog, beide in terme van ekonomie en die omgewing. ‘n Ensimatiese fraksionerings metode was ontwikkel wat die gedeeltelike skeiding van die insek komponente tot gevolge gehad het en groter fraksies was herwin in vergelyking met vorige studies. Die kwantifisering van chitien, afkomstig van insekte, is ‘n problem waarmee die industrie al ‘n hele ruk ‘n stryd mee voer. ‘n Protokol was ontwikkel, afkomstig van die skulpvis industrie, waarmee chitien geïsoleer kan word en die chitien inhoud van insekete dan gravimetries bepaal word. Die ontwikkelde protokol het die akkuraatste en herhaalbaarste resulte vir die kwantifisering van insek chitien, tot op hede, tot gevolg gehad. In geheel was die resultate van die reeks proewe ‘n stap in die regte rigting vir die grootskaalse produksie van insekte.

Doctorate