Author: Trung Nguyen T.
Nguyen T., Trung, 2017 BIOREFINERY PROCESS DEVELOPMENT FOR RECOVERY OF FUNCTIONAL AND BIOACTIVE COMPOUNDS FROM LOBSTER PROCESSING BY-PRODUCTS FOR FOOD AND NUTRACEUTICAL APPLICATIONS, Flinders University, School of Health Sciences
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Australia is the world largest producer and exporter of lobster after America and Canada with annual production around 10,000 tons, valued at approximately $400 million. Australian lobster processing industry annually produces about 3,000 tons of by-products including heads, shells, and livers not only costing about $500,000 for disposal treatments, but also causing pollutions. Continued production of lobster processing by-products (LPBs) without any attempt for efficient utilisation will represent both financial and environmental challenges to the Australian lobster processors. However, chemical approximate of Australian LPBs showed these biomaterials are rich in proteins (43.5 %, 41.1 %, and 29 % in heads, livers, and shells respectively), chitin (25 % in shells), lipids (24.3 % in livers), and minerals (36 % in shells). These components could be efficiently recovered by emerging technologies for applications in food and nutraceutical products. Therefore, utilisation of Australian LPBs for production of functional and nutraceutical ingredients would be promising due to their high global demands together with a wide range of applications of lobster extracts besides the ready availability of LPBs with a large amount.
Although lobster livers found contaminated with arsenic (240 mg/kg) and cadmium (8 mg/kg) the use of supercritical carbon dioxide (SC-CO2) extraction at 35 MPa, 50 oC, in 4 hours could recover nearly 94 % lipids with very low heavy metal contamination compared with the regulation of Australian New Zealand Food Standard. As compare with Soxhlet extraction, the SC-CO2 extracted lipids were significantly rich in polyunsaterated fatty acids (PUFAs, 31.3 vs 7.8 %), ω-3 fatty acids (18 vs 3.1 %), carotenoids (70.4 µg/mL), astaxanthin (41.6 µg/mL) but low arsenic (2.2 vs 31 mg/kg) and cadmium (0.01 vs 0.27 mg/kg). Meat protein in lobster heads was efficiently recovered by ultrasound compared with cold or hot extraction. Nearly 99 % protein were extracted in short time (5 minutes) while the ultrasonic extract had high protein (83.2 vs 78.6 %), essential amino acids (EAAs, 38 vs 30.4 %), and digestibility (78.4 vs 58.4 %). Although shell protein associates tightly with chitin intensified by minerals, it was efficiently removed by the microwave-intensified process. High efficiency of the microwave over the conventional process was indicated by its high weight loss (30.3 vs 24.6 %) and deproteinisation degree (85.8 vs 58.03 %) but low residual protein in deproteinised shells (65.4 vs 96.4 mg/g). Functional and nutritional protein recovered from the microwave process could be used as a food ingredient while the residue could be efficiently demineralised by lactic acid intensified by microwave. The process achieved high demineralisation degree (99.2 %) at mild condition (lactic acid to shell 18 mL/g, 67 oC, 23 minutes). The obtained chitin had low residues of protein (1.6 %) and minerals (0.99 %), which is suitable for advanced applications. Its mineral residue was tenfold lower than that of chitin demineralised by stirring (0.99 vs 10 %). The microwave process could preserve well physicochemical property of chitin indicated by its high acetylation degree (89.9 %) while chemical structure was very similar with high quality chitin analysed by FTIR. Particularly, demineralisation by an environmentally friendly process also allowed recovering minerals from lobster shells with a good mineral profile (87 % calcium) potentially used as another value-added product.
Functional and nutritional extracts recovered from Australian LPBs were demonstrated with high quality attributes, which are great potentials for food and nutraceutical applications. Lobster chitin had high fat, cholesterol binding capacity on several oils (7.5 – 16.1 g/g for fat and 258.7 mg/g for cholesterol) indicates its promising applications for weight loss and cholesterol management products. Lactate salts recovered from lobster shells with richness in calcium could be directly marketable as food ingredients since lactate calcium has several applications in food industry. Moreover, high solubility and bioavailability of lobster calcium over a commercial dietary calcium supplement (60.6 vs 8.3 % and 11.3 vs 1.9 %) demonstrated its promising applications in production calcium supplements. Lobster proteins with high protein content (74 - 83.2 %), rich in EAAs (34 - 39 %), and easy digestibility (78.4 - 96.9 %) could be directly marketable as lobster protein powders (LPPs). Possessing pleasant flavours, applications of LPPs (1 %) and lobster lipids (2 – 4 %) for flavouring purposes such as lobster flavour blends, infused lobster oil, salt plated with lobster lipids were assessed and demonstrated by food panelists. Particularly, richness in PUFAs (31.3 %), omega-3 (18 %), carotenoids (70.4 µg/mL), astxanthin (41.6 µg/mL) of lobster lipids demonstrated this product could be directly marketable as dietary supplement.
Economic feasibility analysis for industrial production of functional and nutraceutical lobster extracts from Australian LPBs using the simulated software (SuperPro) showed investment on this project is highly attractive. This was indicated by its high return on investment but relatively low risk venture. Utilising available LPBs combined with the simple and intensified processes had low capital investment and operational costs. Moreover, high quality of the lobster extracts obtained by these intensified processes made lobster extracts gain highly marketed value for more economic profits to attract potential investors.
Keywords: Biorefinery process development, lobster processing by-products, food functional ingredients, nutraceuticals, supercritical fluid extraction, microwave-assisted extraction, ultrasound-assisted extraction, protein hydrolysate, chitin
Subject: Health Sciences thesis
Thesis type: Doctor of Philosophy
Completed: 2017
School: School of Health Sciences
Supervisor: Prof Wei Zhang