Production and Characterisation of Cell-Bound Lipases Secreted by a Newly Isolated Strain of Geotrichum Candidum

Indigenous lipolytic microorganisms were successfully isolated from soil samples collected from an oil palm plantation and were identified up to the generic level. Over seven hundred microbial colonies were screened and fifteen were found to be positive for the hydrolysis of triolein. Of these, three were yeast species, another three were strains of Geotrichum candidum and the rest were bacteria. Studies on the lipolysis of various natural oils on solid media and in liquid media by the yeasts and the G. candidum strains showed that the latter were the most potent lipolytic organisms. One of the yeasts was found to be weakly lipolytic. These organisms shared two common features: they were not able to hydrolyse tributyrin and they hydrolysed palm kernel olein, which is a lauric acid oil, poorly. Results obtained indicated that these organisms probably elaborated extracellular lipases that possessed some degree of fatty acid specifiCity. The cultural conditions for the maximal hydrolysis of palm olein and for the production of extracellular lipases, both soluble and cell-bound, in submerged culture were determined for one of the G. candidum strains. The optimal pH for lipolysis and maximal production of lipases occurred at pH 7.0 - 7.2. It was discovered that the soluble lipase of this organism was produced constitutively. The cell-bound lipase, however, was found to be an inducible enzyme where production took place only when an oil was added to the culture medium. The type of oil used did not affect production significantly but the presence of sugars and glycerol decreased lipase productivity markedly. High levels of glycerol suppressed growth of the organism. The cell-bound lipase was characterised and was shown to be most active at 43°C and preferred p-nitrophenylcaprylate as the substrate. The kinetics of the hydrolysis of various fatty acid esters of p-nitrophenolwere studied and the Km and Vmax values are presented. When the enzyme was stored at 4°C, a second temperature optimum developed at 30˚C. Continued storage resulted in an increase in the activity at 30˚C with a concomittant decrease in activity at 43˚C. After 6 days, the temperature optimum at 430C was completely lost The shift in temperature optimum from 43˚C to 30˚C could be quickly achieved by heating the ceU-bound lipase at 4O"C for 2 h. The extraction of the cell-bound lipase of G. candidum was simply and easily achieved by shaking induced cells in a buffer solution. Complete extraction could be accomplished in 4-5 h and the total enzyme activity recovered was 4.6-fold greater than what was initially measured and found to be bound to the ceUs. Magnesium ions when added to the extraction buffer caused a delay in the release of the enzyme from the cells. The most efficient pH for extraction was pH 8.4. The extracted lipase was most active at pH 7.8. This enzyme had two temperature optima : 33°C and 4O˚C. The temperature optimum at 33°C was observed only upon storage of the enzyme extract at 4°C. When in the soluble form, the cell-bound lipase preferred p-nitrophenylpalmitate as the substrate, instead of p-nitrophenylcaprylate. The Km and Vmax values of the enzyme for this ester was 6.7 mm and 6.3 x 10₃ umol/min, respectively. The rate of hydrolysis of olive oil exceeded the rate of hydrolysis of tributyrin by 4 times. The profiles of the hydrolysis of a number of fatty acid esters of p-nitrophenol, olive oil and tributyrin of the extracted lipase and those of several commercial lipases were obtained and compared. Purification of both the extracted lipase and soluble lipase was performed and the results obtained are presented. Gel filtration of cell-bound extract and soluble lipase extract on Sephadex G-150 revealed that the G. candidum produced at least two cellbound lipase and two soluble lipase isozymes. The molecular weights of the bound lipases were estimated to be 75,000 and 58,000-61,000, respectively

Production of Cassava Syrup with Glucoamylase Immobilised to Acid-washed Charcoal

Glucoamylase immobilised to acid-washed animaL charcoaL was used to effect the saccharification of Liquefied cassava starch. A 7 DE Liquefied cassava starch solution (30% D. S.) was converted into a 69 DE cassava syrup when the substrate was fed at a ]low rate of 1. 0 mL min }into a packed- bed coLumn reactor of immobilized glucoamyLase. The relationship between the ]low-rate and the extent of saccharification was found to be asymptotic. Much of the brown coLour that deveLoped during the Liquefaction of the substrate was removed when the flow rates was Low, giving a fairly colorless syrup

Tapping the power of enzymes - greening the food industry

Stimulating pressures for better use of renewable resources and clamour for green technologies that will reduce damage to the environment have combined with substantial advances in biotechnology to significantly stimulate the growth of the markets and application areas for enzymes. The impact of genetic and protein engineering on production and modification of the enzyme molecule has been highly visible and this has resulted in a more intense study on tapping the power of enzymes for an even wider range of applications including in food processing. Industrial enzymes are used widely in food processing and technical industries. The total market for them was estimated in 2000 to be in excess of US$ 1.3 billion, with applications as wide-ranging as biological detergents, high fructose corn syrups processing, and cosmetic additives. The manufacture of foods has rapidly changed from an art form to a highly specialised technology based on discoveries, increased availability and translation of knowledge from the basic and applied sciences. In the last 50 years the use of commercial enzymes in food processing has grown from one that is relative insignificant to a role that has become essential. It is such that nowadays, in some food industries, enzymes are used routinely to effect changes during processing that may be otherwise be very difficult to achieve. For some other processes, enzymes appear to be the only logical solution to food transformation and food ingredient production

Effect of Moringa oleifera oil blending on fractional crystallization behavior of palm oil.

The objective of this study was to see the effect of Moringa oleifera oil blending on the fractional crystallization behavior of palm oil. Palm oil blended with Moringa oleifera oil at 20% (w/w) was subjected to crystallization using a dry process at 21 and 18°C and a solvent process at 15 and 10°C. After recording the quantitative recoveries of the liquid and solid fractions, their fatty acid and triacylglycerol compositions, and the thermal profiles were determined by using gas liquid chromatography, high performance liquid chromatography, and differential scanning calorimetry, respectively. Results showed that the yield recoveries of liquid fractions under solvent-assisted crystallization were higher than those obtained by dry-crystallization conditions. Almost all of the liquid fractions isolated had experienced a significant (p < 0.05) increase in oleic acid as well as triolein contents. Among the solid fractions, those isolated by dry-crystallization were found to be higher (p < 0.05) in oleic acid and triolein contents than the reference stearin sample. Although the thermal profiles of the solid and liquid fractions derived by different methods looked similar to those of the two reference samples, remarkable differences were noticed with regard to the onset of crystallization and the position of the thermal transitions

Fatty acid ratios and their relative amounts as indicators of oil stability and extent of oil deterioration during frying.

Palm olein (PO), canola (CLO), soybean (SBO) and Moringa oleifera seed oils (MoO) were used to fry potato chips for 6 h a day for 5 days and extent of deterioration determined. FA ratios C 18:1/ C 18:2 + C 18:3 and amounts of C 18:1 + C 16:0 were compared to changes in total polar compounds. TPC in MoO (20.78%) and PO (21.23%) were significantly lower than those in CLO (28.73%) and SBO (31.82%). There was a decrease in the amounts of C 18:2 from day 0 to 5 in PO (10.80 to 8.37%), CLO (22.76 to 19.92%) and SBO (53.00 to 51.57%) and a decrease in C 18:3 in CLO (6.77 to 4.55%), respectively, and an increase in C 16:0; MoO (6.10 to 9.60%) and PO (37.70 to 41.99) and a decrease in C 18:1; (74.40 to 73.03%) in MoO, respectively. There was a negative correlation (r = - 0.9919) between C 18:1/ C 18:2 + C 18:3 and TPC produced in PO, CLO and SBO

Alcohol Production from Cassava Starch by Co-immobilized Zymomonas mobilis and Immobilized Glucoamylase

Simultaneous saccharification and fermentation of dextrin£zed cassava starch to glucose and alcohol, respectively, were carried out by co-immobilized Zymomonas mobilis and immobilz'zed glucoamylase (IG). Calcium alginate-entrapped cells and IG (4 : 1 ratio) gave an alcohol productivity of 0.30 glgww cellslh in a batchfermentation process. For continuous fermentation, 54.3 gil alcohol was produced at a dilution rate of 0.3Ih. 60% of the initial activity was lost within 3 days and, thereafter, the system entered a slowly decreasing phase ofalcohol production

Improvement of the specific activity of the extracted mycelium-bound lipase of Aspergillus flavus

Specific activity of lipase extracted from the mycelium of Aspergillus flavus, obtained from 3-day-old culture, increased nearly two times higher than from its culture supernatant. Different types of parameters were tested to optimise the extraction of mycelium-bound lipase. Highest specific activity of A. flavus lipase was obtained at 30 °C for 30 min with the agitation rate of 200 rev/min. Tris-HCl buffer (0.05 M) at pH 8.2 was the best extractant followed by Triton X-100 (0.1%), EDTA (0.01 M), NaCl (1 M) and Tween-80 (0.01%). The optimised conditions developed for the extraction of mycelium-bound lipase improved the purity of this lipase by 2.9 times higher than the control

Comparison of melting behaviors of edible oils using conventional and hyper differential scanning calorimetric scan rates

HyperDSC™ (fast scan rate) was used to study the melting behavior of canola (CLO), sunflower (SFO), palm olein (PO), rice bran oils (RBO), and cocoa butter (CB), and was compared to the melting behaviors using conventional DSC. There was an increase in sensitivity with increase in scan rate. Slow scan rate (5 to 20C/min) gave low sensitivity, which increased when the scan rates were increased to 50, 100 and 200C/min. Peak resolution was affected by scan rate depending on the sample weight. Increase in the size of sample coupled with the use of fast scan rate decreased the peak resolution. Generally small sample sizes gave better peak resolution. Results of the effect of scan rate on glass transition (Tg) shows that Tg, which is a weak transition especially in crystalline and low amorphous materials was not detected using conventional scan rates (5 to 20oC/min). It was however detected using of hyperDSC™ scan rates (100 to 200oC/min). Increasing the scan rate resulted in an increase in the peak temperature and the elimination of shoulder peaks, which were caused due to the polymorphic behavior of the triacylglycerols in the oils. The increase in peak temperature caused a shift in the peak position towards a higher temperature value. There is a positive correlation between the peak temperature and scan rate. The correlation coefficients (r) for CLO, SFO, PO, RBO and CB were 0.96, 0.95, 0.97, 0.96 and 0.96 respectively

Factors affecting fast food consumers’ intention to use menu labeling in Klang Valley, Malaysia

Menu labeling is an attempt to educate consumers about the nutrition value of the foods. The importance of using menu labeling has been highlighted in many studies in the past. Although public health programs are educating public on obesity but still this phenomenon is a serious problem in Malaysia. This study identified factors that influence intention to use menu labeling among fast food consumers in Malaysia. The research was conducted among 395 adults in Klang Valley. Respondents completed a self-administrative questionnaire which was adapted from previous studies. Results revealed that attitude, subjective norms and perceived behavioral control had statistically significant positive association with intention and each was significant predictors of intention to use menu labeling and together explained 41% of its variance. The most effective factor was attitude, followed by subjective norms and perceived behavioral control. The outcomes of this study suggested that nutritional knowledge of consumers does not have effect on consumer’s intention to use menu labeling; therefore nutritional knowledge of fast food consumers must be improved. Fast food restaurants have to put more effort on encouraging customers to use menu labeling by making the label more accessible and in a user friendly format