Study on preparing fatty acid by hydrolyzing Jatropha Curcasl Oil with lipase
Used tween-80 as emulsifier, industrial lipase as catalyst to hydrolyze Jatropha Curcasl Oil and make mixed fatty acid. We discussed the enzyme concentration, substrate concentration, temperature and time on hydrolysis. Through the experiment, we found that when we used emulsifier which contains 2% oil in the system, we could get the optimal parameter for hydrolysis of waste oil from restaurants as follows: concentration of catalyst 4% (W/W), weight ratio of oil to water 1:4 (W/W), temperature at 40°C, and hydrolysis time is 32h. Under these conditions, the AV(acid value) of hydrolyzed rapeseed oil reached 163.2 mg KOH/g, and hydrolytic rate arrived at 89.6%.
Enzymatic fat hydrolysis and synthesis
The hydrolysis of tallow, coconut oil and olive oil, by lipase fromCandida rugosa, was studied. The reaction approximates a firstorder kinetics model. Its rate is unaffected by temperature in the range of 26–46 C. Olive oil is more rapidly hydrolyzed compared to tallow and coconut oil. Hydrolysis is adversely affected by hydrocarbon solvents and a nonionic surfactant. Since amounts of fatty acids produced are almost directly proportional to the logarithms of reaction time and enzyme concentration, this relationship provides a simple means of determining these parameters for a desired extent of hydrolysis. All three substrates can be hydrolyzed, almost quantitatively, within 72 hr. Lipase fromAspergillus niger performs similarly. The lipase fromRhizopus arrhizus gives a slow hydrolysis rate because of its specificity for the acyl groups attached to the α-hydroxyl groups of glycerol. Esterification of glycerol with fatty acid was studied with the lipase fromC. rugosa andA. niger. All expected five glycerides are formed at an early stage of the reaction. Removal of water and use of excess fatty acid reverse the reaction towards esterification. However, esterification beyond a 70% triglyceride content is slow.
Microbial flora of frozen tail meat from captive Nile crocodiles (Crocodylus niloticus).
Frozen tail meat samples from nine Nile crocodiles (Crocodylus niloticus) were evaluated for microbial numbers and types. Microbial analyses yielded a mean aerobic plate count (APC, 30 degrees C) of 4.86 log cfu/g, a mean coliform count (TC, 37 degrees C) of 3.77 log cfu/g and a mean faecal coliform count (FC, 44 degrees C) of 3.40 log cfu/g. Salmonella was isolated from three samples, and beta-haemolytic streptococci from two samples. Yersinia, Aeromonas, Staphylococcus aureus and Bacillus cereus were not isolated. Typical bacterial genera recovered included Flavobacterium, Pseudomonas, Acinetobacter, Enterobacter, Moraxella, Micrococcus, Staphylococcus and Streptococcus.