Selim Kermasha

Encapsulation in the food industry: A review

Encapsulation involves the incorporation of food ingredients, enzymes, cells or other materials in small capsules. Applications for this technique have increased in the food industry since the encapsulated materials can be protected from moisture, heat or other extreme conditions, thus enhancing their stability and maintaining viability. Encapsulation in foods is also utilized to mask odours or tastes. Various techniques are employed to form the capsules, including spray drying, spray chilling or spray cooling, extrusion coating, fluidized bed coating, liposome entrapment, coacervation, inclusion complexation, centrifugal extrusion and rotational suspension separation. Each of these techniques is discussed in this review. A wide variety of foods is encapsulated--flavouring agents, acids bases, artificial sweeteners, colourants, preservatives, leavening agents, antioxidants, agents with undesirable flavours, odours and nutrients, among others. The use of encapsulation for sweeteners such as aspartame and flavours in chewing gum is well known. Fats, starches, dextrins, alginates, protein and lipid materials can be employed as encapsulating materials. Various methods exist to release the ingredients from the capsules. Release can be site-specific, stage-specific or signalled by changes in pH, temperature, irradiation or osmotic shock. In the food industry, the most common method is by solvent-activated release. The addition of water to dry beverages or cake mixes is an example. Liposomes have been applied in cheese-making, and its use in the preparation of food emulsions such as spreads, margarine and mayonnaise is a developing area. Most recent developments include the encapsulation of foods in the areas of controlled release, carrier materials, preparation methods and sweetener immobilization. New markets are being developed and current research is underway to reduce the high production costs and lack of food-grade materials.

Esterification and Interesterification Activities of Lipases from Rhizopus niveus and Mucor miehei in Three Different Types of Organic Media: A Comparative Study

Abstract The esterification of oleic acid by ethanol using lipases from Rhizopus niveus and Mucor miehei as catalysts was evaluated in microaqueous, biphasic (n-hexane-water) and surfactant-enriched biphasic systems containing different amounts of water. The results showed that for R. niveus lipase-catalyzed esterification in a microaqueous system, a water content corresponding to a water activity of 0.75 is optimal from a kinetic point of view. In biphasic systems, the influence of the water content on the thermodynamics of the reaction and the effect of the interfacial area between phases on the velocity of the biocatalysis were demonstrated. In addition, the water content was shown to influence the velocity of the reaction in the surfactant-enriched biphasic system. It was also demonstrated that, from a kinetic point of view, both lipases are by far more efficient in biphasic systems. From a thermodynamic point of view, biphasic systems allow interesting esterification rates to be obtained whereas they were shown to be less suitable than the microaqueous system to carry on interesterification reactions.

Determination of the positional distribution of fatty acids in butterfat triacylglycerols

Triacylglycerol (TAG) standards were separated by analytical high-performance liquid chromatography (HPLC) with laser light-scattering detection (LLSD). A high sensitivity for TAGs was observed with LLSD whereas poor sensitivity was observed with ultraviolet detection. The HPLC-LLSD analytical separation of butterfat TAGs showed that the TAGs were eluted according to increasing carbon number. Preparative HPLC-LLSD was used to characterize butterfat TAGs that contained hypercholesterolemic fatty acids (laurate, myristate, palmitate) with carbon chainlengths of 12 or greater. These TAG fractions accounted for 29.2% of the total butterfat TAGs. Analysis of the positional distribution of fatty acids of selected butterfat TAGs containing hypercholesterolemic fatty acids showed the presence of positional isomers in each of these fractions. These butterfat TAGs also showed the predominant presence of hypercholesterolemic fatty acids at thesn-2 position. The characterization of the positional distribution of hypercholesterolemic fatty acids in butterfat TAGs is the first step for the determination of the metabolic role of the positional distribution in the hypercholesterolemic effects of butter.

Enzymatic synthesis of structured phenolic lipids by incorporation of selected phenolic acids into triolein

The synthesis of structured phenolic lipids by lipase-catalyzed transesterification of selected phenolic acids, including p-hydroxyphenyl acetic, p-coumaric, sinapic, ferulic and 3,4-dihydroxybenzoic acids, with triolein was investigated. The highest enzymatic activity (248 nmol esterified phenolic acid/g solid enzyme/min) and bioconversion (62%) was obtained for the transesterification of p-hydroxyphenyl acetic acid with triolein. In addition, the transesterification of p-coumaric with triolein resulted in a higher enzymatic activity (87 nmol esterified phenolic acid/g solid enzyme/min) and bioconversion (46%) than those obtained for the transesterfication of ferulic and sinapic acids. The results also showed that using p-hydroxyphenyl acetic, p-coumaric and ferulic acids as substrate, the maximum bioconversion of phenolic monoacylglycerols was close to that of phenolic diacylglycerols. Although p-coumaric acid had very low radical scavenging activity (2%) compared to that of ferulic acid (62%), the p-coumaroylated lipids demonstrated a higher scavenging potency (16%) than that of the feruloylated one (10%).

Analyses of phenolic and furfural compounds in concentrated and non-concentrated apple juices

Abstract A high-performance liquid chromatography (HPLC) analytical method, using a combination of ultraviolet-diode array (UV) and electrochemical (EC) detectors, was developed for the characterization and quantification of phenolic and furfural compounds in apple juice. The limits of detection of phenolic compounds with EC detection were 4–500 times greater than those obtained with UV detection. The HPLC method allowed the identification and quantification of the major (chlorogenic and coumaroylquinic acids and phloridzin) and minor (caffeic, p-coumaric, ferulic, gallic and protocatechuic acids, and catechin) phenolic compounds, as well as 5-hydroxymethyl-2-furaldehyde and 2-furaldehyde in apple juice. The total phenolic content in apple juices of various origins varied from 28.85 to 115.49 mg/l. The concentrations of phenolic and furfural compounds varied widely among the non-concentrated and concentrated apple juices.

Lipase-catalyzed synthesis of phenolic lipids from fish liver oil and dihydrocaffeic acid

The enzymatic synthesis of phenolic lipids by lipase-catalyzed transesterification of dihydrocaffeic acid (DHCA) with fish liver oil was investigated in a selected organic solvent medium. These synthesized phenolic lipids have potential use as nutraceutical products. Using a molar ratio of 1:8 DHCA to fish liver oil in hexane:2-butanone mixtures of 75:25 and 85:15 (v/v), the lipase-catalyzed reaction resulted in maximum conversion of 55.8 and 65.4%, respectively. The maximum conversion of phenolic monoacylglycerols in hexane:2-butanone mixture of 75:25 and 85:15 (v/v) was 40.3 and 37.7%, respectively; using the same solvent mixtures, the conversions of the phenolic diacylglycerol were 15.8 and 36.8%, respectively. Hexane:2-butanone mixture of 75:25 (v/v) was, therefore, the best organic solvent mixture for the production of phenolic monoacylglycerols, while that of 85:15 (v/v) was best for the production of phenolic diacylglycerols. The phenolic lipids produced from the fish liver oil and DHCA demonstrated antioxidant property as indicated by its free radical scavenging capacity.

Characterization of Selected Cellulolytic Activities of Multi-enzymatic Complex System from Penicillium funiculosum

The presence of endo-1,4-beta-D-glucanase, cellobiohydrolase, and beta-glucosidase activities in a multi-enzymatic complex system from Penicillium funiculosum was investigated. The interesting feature of these enzymes is their synergistic action for the hydrolysis of the native cellulose into glucose units. Both endo-1,4-beta-D-glucanase and cellobiohydrolase showed broader pH activity profiles, with pH optima of 4.0 and 4.0-5.0, respectively. However, beta-glucosidase activity showed a narrow pH-activity profile, with an optimum pH of 4.5. The different cellulolytic activities were stable in the acidic pH range of 2.5-6.0 and showed a similar optimal temperature of 60 degrees C. Although beta-glucosidase has shown a close catalytic efficiency as that of endo-1,4-beta-D-glucanase, its thermal stability was lower. However, the thermal stability profile of cellobiohydrolase was close to that of endo-1,4-beta-D-glucanase. The results also revealed the presence of high levels of endo-1,3-1,4-beta-D-glucanase, endo-1,3-beta- d-glucanase, and pectinase activities in the multi-enzymatic cellulolytic complex system. Moreover, the investigated multi-enzymatic complex system was effective in degrading the nonstarch polysaccharides of soybean meal.

Lipase-catalyzed esterification of selected phenolic acids with linolenyl alcohols in organic solvent media

Lipase-catalyzed esterification of selected phenolic acids with linolenyl alcohols was investigated in selected organic solvent media. The enzyme activity for the esterification of dihydrocaffeic acid with linolenyl alcohol in solvent mixtures of hexane/2-butanone of 75∶25 (v/v) and 65∶35 (v/v) was 0.88 and 0.47 μmol of esterified dihydrocaffeic acid/(g of solid enzyme·min), respectively, with a corresponding esterification yield of 76 and 58%, respectively. However, the esterification of ferulic acid with linolenyl alcohol in the reaction medium of hexane/2-butanone of 65∶35 (v/v) resulted in a low yield (16%). Using the reaction medium of hexane/2-butanone of 75∶25 (v/v), an increase in linolenyl alcohol concentration with a concomitant use of a constant amount of dihydrocaffeic acid resulted in an increase in esterification yield. The highest esterification yield of 99% was obtained with a ratio of dihydrocaffeic acid to linolenyl alcohol of 1∶8 after 7 d of reaction. Biosynthesis of the end product, linolenyl dihydrocaffeate, was confirmed by electrospray ionization mass spectroscopy structural analysis; the esterproduct demonstrated an antiradical activity close to that of α-tocopherol.

Comparative high-performance liquid chromatographie analyses of cholesterol and its oxidation products using diode-array ultraviolet and laser light-scattering detection

Abstract Comparative high-performance liquid Chromatographic (HPLC) analyses of cholesterol and its oxidization products (COPS) showed that cholesterol, cholestane, 7-ketocholesterol and 7α, 7β-, 20- and 25-hydroxy-cholesterol were detected by both ultraviolet (UV) and laser light-scattering detection (LLSD). In addition, the use of LLSD allowed the detection of cholestanetriol and α- and β-epoxides. The limits of detection of COPS varied from 0.5 to 25 μg ml , depending on both the compound and the detector. The HPLC analyses demonstrated a linear correlation between the UV response and concentrations of products in the range 0–500 μg ml whereas a linear correlationship with LLSD was obtained by plotting logarithmic coordinates in the same range.

Characterization of a lipoxygenase extract from Geotrichum candidum

Abstract Geotrichum candidum was cultivated and harvested after 8 days of incubation, a period that corresponded to the maximal dry weight of mycelium as well as to optimal lipoxygenase (LOX) activity. A partially purified LOX enzymic extract was obtained by ammonium sulfate precipitation. The LOX extract exhibited two major activities, at pH 8.00 and 3.75 using linoleic acid as substrate. At pH 3.75, the enzymic extract displayed the highest specific activity using linolenic and linoleic acids as substrates whereas, at pH 8.00, maximal LOX activity was obtained using arachidonic and linoleic acids. At pH 3.75, fatty acid acylglycerols were enzymically oxidized with a similar efficiency to that obtained with free fatty acids. K m and V max values as well as the effect of a wide range of chemical substances on LOX activity were also investigated. High-performance liquid chromatography and gas chromatography/mass spectrometry analyses showed that LOX activity in the microbial enzymic extract converted linoleic acid to the corresponding 9- and 13-hydroperoxides.