Purification and Characterization of Lipase Produced by Leuconostoc mesenteroides Subsp. mesenteroides ATCC 8293 Using an Aqueous Two-Phase System (ATPS) Composed of Triton X-100 and Maltitol.

Purification of lipase produced by L. mesenteroides subsp. mesenteroides ATCC 8293 was conducted for the first time using a novel aqueous two-phase system (ATPS) composed of Triton X-100 and maltitol. The partitioning of lipase was optimized according to several parameters including pH, temperature, and crude load. Results showed that lipase preferentially migrated to the Triton X-100 rich phase and optimum lipase partitioning was achieved in ATPS at TLL of 46.4% and crude load of 20% at 30 °C and pH 8, resulting in high lipase purification factor of 17.28 and yield of 94.7%. The purified lipase showed a prominent band on SDS-PAGE with an estimated molecular weight of 50 kDa. The lipase was stable at the temperature range of 30⁻60 °C and pH range of 6⁻11, however, it revealed its optimum activity at the temperature of 37 °C and pH 8. Moreover, lipase exhibited enhanced activity in the presence of non-ionic surfactants with increased activity up to 40%. Furthermore, results exhibited that metals ions such as Na⁺, Mg2+, K⁺ and Ca2+ stimulated lipase activity. This study demonstrated that this novel system could be potentially used as an alternative to traditional ATPS for the purification and recovery of enzymes since the purified lipase still possesses good process characteristics after undergoing the purification process.

Antioxidant effect of supercritical CO2 extracted Nigella sativa L. seed extract on deep fried oil quality parameters.

Effect of supercritical CO2 extracted Nigella sativa L. seed extract (NE) on frying performance of sunflower oil and refined, bleached and deodorized (RBD) palm olein was investigated at concentrations of 1.2 % and 1.0 % respectively. Two frying systems containing 0 % N. sativa L. extract (Control) and 0.02 % butylated hydroxytoluene (BHT) were used for comparison. Physicochemical properties such as fatty acid composition (FAC), Peroxide Value (PV), Anisidine Value (AV), Totox Value (TV), Total Polar Content (TPC), C18:2/C16:0 ratio and viscosity of frying oils were determined during five consecutive days of frying. Results have shown that N. sativa L. extract was able to improve the oxidative stability of both frying oils during the frying process compared to control. The stabilizing effect of antioxidants were in the order of BHT > NE. RBD palm olein was found to be more stable than sunflower oil based on the ratio of linoleic acid (C18:2) to palmitic acid (C16:0) and fatty acid composition.

Effects of storage and yogurt matrix on the stability of tocotrienols encapsulated in chitosan-alginate microcapsules.

Tocotrienol microcapsules (TM) were formed by firstly preparing Pickering emulsion containing tocotrienols, which was then gelled into microcapsules using alginate and chitosan. In this study, we examined the stability of TM during storage and when applied into a model food system, i.e. yogurt. During storage at 40°C, TM displayed remarkably lower tocotrienols loss (50.8%) as compared to non-encapsulated tocotrienols in bulk oil (87.5%). When the tocotrienols were incorporated into yogurt, the TM and bulk oil forms showed a loss of 23.5% and 81.0%, respectively. Generally, the tocotrienols were stable in the TM form and showed highest stability when these TM were added into yogurt. δ-Tocotrienol was the most stable isomer in both forms during storage and when incorporated into yogurt. The addition of TM into yogurt caused minimal changes in the yogurt's color and texture but slightly altered the yogurt's viscosity.

Maillard Reaction of Pidan White as Inhibited by Chinese Black Tea Extract (Camellia sinensis) in the Pickling Solution.

Changes in Maillard reaction of pidan white were monitored with A294, fluorescence intensity, and browning intensity during pickling in the absence and presence of Chinese black tea extract (Camellia sinensis) at levels of 2% and 5% together with 0.2% ZnCl2 or 0.2% CaCl2 up to 3 wk, followed by ageing for another 3 wk. Browning intensity and A294 of pidan white increased with increasing pickling/ageing, while fluorescence intensity decreased during ageing (p<0.05), irrespective of treatments. At wk 6, pidan white treated with 0.2% ZnCl2 and 0.2% CaCl2 showed slightly higher browning intensity, fluorescence intensity and A294 than those treated with divalents together with Chinese black tea (p<0.05). Free amino group and sugar contents showed continuous decrease during pickling and ageing irrespective of tea and cations used. However, pidan treated without Chinese black tea extract showed significantly lower free amino group and sugar during the ageing of 6 wk (p<0.05). Thus, Chinese black tea extract had an inhibitory effect on the Maillard reaction during ageing of pidan white.

Co-solvent selection for supercritical fluid extraction of astaxanthin and other carotenoids from Penaeus monodon waste.

In recent years, astaxanthin is claimed to have a 10 times higher antioxidant activity than that of other carotenoids such as lutein, zeaxanthin, canthaxanthin, and ß-carotene; the antioxidant activity of astaxanthin is 100 times higher than that of α-tocopherol. Penaeus monodon (tiger shrimp) is the largest commercially available shrimp species and its waste is a rich source of carotenoids such as astaxanthin and its esters. The efficient and environment-friendly recovery of astaxanthins was accomplished by using a supercritical fluid extraction (SFE) technique. The effects of different co-solvents and their concentrations on the yield and composition of the extract were investigated. The following co-solvents were studied prior to the optimization of the SFE technique: ethanol, water, methanol, 50% (v/v) ethanol in water, 50% (v/v) methanol in water, 70% (v/v) ethanol in water, and 70% (v/v) methanol in water. The ethanol extract produced the highest carotenoid yield (84.02 ± 0.8 µg/g) dry weight (DW) with 97.1% recovery. The ethanol extract also produced the highest amount of the extracted astaxanthin complex (58.03 ± 0.1 µg/g DW) and the free astaxanthin content (12.25 ± 0.9 µg/g DW) in the extract. Lutein and ß-carotene were the other carotenoids identified. Therefore, ethanol was chosen for further optimization studies.

Effect of organic-phase solvents on physicochemical properties and cellular uptake of astaxanthin nanodispersions.

A simplex centroid mixture design was used to study the interactions between two chosen solvents, dichloromethane (DCM) and acetone (ACT), as organic-phase components in the formation and physicochemical characterization and cellular uptake of astaxanthin nanodispersions produced using precipitation and condensation processes. Full cubic or quadratic regression models with acceptable determination coefficients were obtained for all of the studied responses. Multiple-response optimization predicted that the organic phase with 38% (w/w) DCM and 62% (w/w) ACT yielded astaxanthin nanodispersions with the minimum particle size (106 nm), polydispersity index (0.191), and total astaxanthin loss (12.7%, w/w) and the maximum cellular uptake (2981 fmol/cell). Astaxanthin cellular uptake from the produced nanodispersions also showed a good correlation with their particle size distributions and astaxanthin trans/cis isomerization ratios. The absence of significant (p > 0.05) differences between the experimental and predicted values of the response variables confirmed the adequacy of the fitted models.