Physical, chemical and functional characterization of edible cricket (Acheta domesticus) protein concentrate

Abstract

Edible insects have been shown to be good sources of proteins and a potential solution to food and nutrition insecurity. Therefore the aim of this study was to investigate physico- chemical and functional characteristics of cricket powder defatted using two different methods for future utilization as a food ingredient in processed food products. Adult crickets were obtained from JKUAT farm in Kenya, dried under controlled conditions and ground to powder. The proteins were concentrated using two solvent namely; hexane which resulted to a filtrate (HE) and water which resulted to a filtrate (AE-Pellet) and a residue (AE-Residue). Yield was determined gravimetrically and colour by colorimetric method. The crude protein, crude fibre, crude fat, crude ash and available carbohydrates were determined using standard analytical methods. Protein digestibility was determined using enzymatic digestion method while protein fractions were extracted and quantified gravimetrically. The water holding capacity was determined using standard AACC procedure. Emulsion capacity, emulsion stability, foaming capacity and foam stability was investigated. The effect of sodium chloride (NaCl) and pH on the functional properties was also determined. HE recorded high values for yield, lightness, hue angle and protein content (P <0.0001, P = 0.0003). Hexane extraction was significantly efficient in extracting fat in relation to aqueous extraction (P < 0.0001). Crude fiber and protein digestibility were not significantly affected by concentration method (p= 0.0476, 0.0822). Aqueous extraction recorded significantly higher values for Globulin (19.42%), prolamin (6.26%) and Glutelin (10.10%). AE Pellet had higher emulsion capacity (41.70%) and emulsion stability (33.61%), foaming capacity (11.11%) and foam stability (10.15%). At pH 12 the protein solubility, emulsion capacity and water holding capacity of the protein concentrates was optimum. Increase in NaCl concentration resulted to a significant decline in emulsion capacity and stability of the protein concentrates (P < 0.0001). At Ph 4 and 4% NaCl foaming capacity was optimum with AE Pellet recording the highest values (21.73%).The least gelation concentration was 30% with only AE Pellet showing gelation potential. The extraction method, pH and NaCl significantly influenced the physico-chemical and functional properties of the protein concentrates