Abstract. The effect of microwave pretreatment of catfish processing waste on oil recovery and quality was investigated. Fish oil was extracted using the enzymatic hydrolysis using alcalase enzyme after the microwave pretreatment. The effect of microwave power and microwave pretreatment times was evaluated. The results revealed that a highest yield of 9.25% when catfish waste was treated at 110 W for 60 s. This condition was found as the most appropriate condition of microwave pretreatment since it decreased the extraction time from 150 min to up to 30 min. Analysis of oil quality indices (e.g. acid value, p-anisidine value, peroxide value) extracted by microwave pretreatment and non-pretreatment indicated that catfish oil from both processes has comparatively similar fatty acids composition. In addition, catfish oil was extracted by microwave pretreatment and enzymatic hydrolysis had lower lipid oxidation compared to several standards.

Effect of ultrasonic extraction on total phenolic content (TPC) of two algae; Spirogyra sp. and Cladophora glomerata was evaluated. In this study, the solid/solvent ratio of 1/30 (wt/vol) and extraction temperature of 40°C gave higher TPC value in two algae. This ratio and temperature was applied in the ultrasonic-assisted extraction (UAE) of phenolic extraction. This study compared the TPC obtained from two algae extracts without involving ultrasonic and the TPC obtained from the UAE. The results showed that the TPCs value of two algae was significantly higher in the UAE compared to the TPCs in the non-UAE. The increasing in the TPCs of two algae was between ~23% and ~39% when 5 to 20 min of ultrasonication applied in the extraction. Ultrasonication duration of 15 min and 10 min in Spirogyra sp. and Cladophora glomerata gave the highest TPCs which the value was significantly higher compared to the other duration.

Three different catfish oil extraction processes were used to extract oil from catfish viscera: process P1 involved a mixture of ground catfish viscera and water, no heat treatment and centrifugation; process P2 involved ground catfish viscera (no added water), heat treatment and centrifugation; process P3 involved a mix true of ground catfish viscera and water, heat treatment and centrifugation. Chemical and physical properties of the resulting of catfish oils were evaluated. The P3 process recovered significantly higher amounts of crude oil from catfish viscera than the other extraction methods. The P3 oil also contained a higher percent of free fatty acid and peroxide values than P1and P2 oils. Oleic acid in catfish oil was the predominant fatty acid accounting for about 50% of total fatty acids. The apparent viscosity at-5 and 0 C was significantly higher (P < 0.05) than those at 5, 10, 15, 20, and 30 C.