Chitin analysis of insects (mealworm and cricket)

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Title: Chitin analysis of insects (mealworm and cricket)
Author: Han, Xiaocui
Other contributor: Helsingin yliopisto, Maatalous-metsätieteellinen tiedekunta, Elintarvike- ja ympäristötieteiden laitos
University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Environmental Sciences
Helsingfors universitet, Agrikultur- och forstvetenskapliga fakulteten, Institutionen för livsmedels- och miljövetenskaper
Publisher: Helsingin yliopisto
Date: 2018
Language: eng
Thesis level: master's thesis
Discipline: Food Science
Food Science
Food Science
Abstract: The literature review dealt with the chemical and physical properties of chitin polymer and its degradation product glucosamine. Particular emphasis was given to studies on the analytical methods of determination of chitin from various products including gravimetrical, spectrophotometric and chromatographic methods. The aim of this study was to optimize an analytical method to determine insect chitin and to apply the method to quantify chitin in whole insects and their soluble protein fractions. Two species of insects were selected: mealworm larvae (Tenebrio molitor) and cricket (Acheta domesticus). Whole insects and their protein fractions were treated with alkaline to remove protein. Chitin in de-proteined insect material was then hydrolysed into glucosamine using 6M HCl. Glucosamine from the hydrolysate was determined using chromatographic and spectrophotometric methods, where chromatographic method was optimized and validated. UPLC-FLR method was specific for glucosamine and the UPLC system could separate two target peaks (glucosamine isomers: α and β). Glucosamine content was calculated using a calibration curve which showed excellent linearity in range 0.0033~24.0 ng/inj. with the determination coefficient more than 0.999 during the study period. The instrumental limit of detection and limit of quantification were 0.00095 ng/inj. (2 µL) and 0.0033 ng/inj. (7 µL), indicating a satisfied sensitivity. Recovery of glucosamine spiked to sample matrix (de-proteined cricket flour) following chitin hydrolysis was not satisfactory (~75%) using HPLC-FLR method, which indicated that spectrophotometric method gave chitin amount closer to the true value due to a higher recovery (>90%). Major findings on chitin amount was ~5% on dry matter basis in both mealworm and cricket. A small percentage of chitin was found in insect protein fractions extracted by 0.1M NaCl.

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