Stability of monoterpenes encapsulated in gum Arabic by spray-drying

Microencapsulation using spray-drying was tested with gum arabic and monoterpenes as wall and core materials, respectively. Citral, linalool, beta-myrcene, limonene, and beta-pinene were used at concentrations of 10, 20, and 30% with respect to the wall material. The greatest percentages of retention occurred at a concentration of 10%. Linalool and citral presented the greatest losses with increase in concentration. The hydrocarbons used were the most retained. Of the hydrocarbons, beta-pinene was better retained in the capsules than limonene, and beta-myrcene was the least retained of all. The capsules presented similar external morphologies, with no apparent cracks or porosity and an average size varying between 15.7 and 23.2 microm. The stability of the capsules to temperature was monitored for 33 days. The degradation products of the monoterpenes were evaluated. The results indicated a greater stability of the capsules containing beta-pinene and citral than of those containing linalool and beta-myrcene presenting the lowest retentions.     

Production of saturated acyl L-ascorbate by immobilized lipase using a continuous stirred tank reactor

6-O-decanoyl, 6-O-dodecanoyl, or 6-O-tetradecanoyl L-ascorbate was continuously produced at 50 degrees C using a continuous stirred tank reactor (CSTR) with an immobilized lipase, Chirazyme L-2 C2, from Candida antarctica. Acetone was used as the reaction medium. For each saturated acyl L-ascorbate, the productivity of ca. 60 g/L reactor/day was achieved for at least 11 days. The solubility of the saturated acyl L-ascorbate in the soybean oil or water was measured at various temperatures. The solubilities in both the soybean oil and the water were higher for L-ascorbate with a shorter acyl chain. The acyl chain dependence of the solubility in water was stronger than that of the solubility in soybean oil. The temperature dependences of the solubility in both soybean oil and water could be expressed by the van't Hoff equation, and the dissolution enthalpy (DeltaH) values for the soybean oil and water were about 20 and 90 kJ/mol, respectively, irrespective of the acyl chain length. The radical scavenging activities of L-ascorbic acid and the saturated acyl L-ascorbates against 1,1-diphenyl-2-picrylhydrazyl free radical were ca. 95% for all of the compounds, and the introduction of a saturated acyl group to the L-ascorbic acid did not affect the activity.     

Inhibition of linoleic acid oxidation by interaction with a protein-rich oat fraction

A protein-rich fraction from oat was found to protect linoleic acid against oxidation in an aqueous suspension containing soybean lipoxygenase-1 and micellar linoleic acid. In this system the oat fraction reduced the initial oxidation rate of linoleic acid by 50% when the oat fraction/linoleic acid ratio was 5:1 (w/w). The oat fraction did not act on the lipoxygenase enzyme but reduced the concentration of linoleic acid that serves as a substrate for lipoxygenase-1. To achieve the reduction in the oxidation rate a contact between linoleic acid and the oat fraction was required. The efficiency of the protection was dependent on the duration of this contact: the maximum protection was reached after a 5-min incubation period. However, total cessation of oxidation was not reached with any concentration of the oat fraction, indicating that the oxidizible and non-oxidizible forms of linoleic acid are in equilibrium. Because lipoxygenase-1 prefers the monomeric form of the substrate, the present findings agree with the hypothesis that the oat fraction reduces the concentration of monomolecular form of substrate. In most food systems monomolecular free linoleic acid is liberated slowly and at relatively low concentrations, therefore, even a small amount of the oat fraction would guard the system from oxidative deterioration.     

Effect of arabic gum and xanthan gum on the stability of pesticide in water emulsion

The effect of arabic gum (AG) and xanthan gum (XG) on the physicochemical properties of 2% pesticide avermyctin in water emulsions was systematically investigated by measuring creaming stability, droplet size, zeta potential, and rheology. Addition of AG and XG had significant influence on the physicochemical properties of emulsions. Emulsions showed high stability throughout the storage time in the AG concentration range of 0-0.14%. In contrast, addition of XG induced the apparent creaming of emulsion as the XG concentration increased from 0.011 to 0.15%, which might be well explained by the depletion flocculation of droplets. The droplet diameter increased progressively with increasing AG concentration; however, it sharply grew initially with XG concentration and reached a maximum, followed by a gradual decrease. Zeta potential increased gradually as AG concentration was lower than 0.081%, followed by a slight decrease, whereas it reduced dramatically as XG concentration increased from 0.011 to 0.040% and then remained almost unchanged. In the AG concentration range of 0-0.14%, the emulsion exhibited typical Newtonian flow behavior and the viscosity decreased a little. The XG emulsion exhibited Newtonian flow behavior at low XG concentrations (≤0.019%), whereas, non-Newtonian flow behavior was displayed at relatively high XG concentrations (>0.019%), wherein viscosity value and yield value increased gradually as XG concentration increased. In addition, the curves of shear stress versus shear rate for XG emulsion and solution were well fitted by a power law model and the Herschel-Bulkley model; the Herschel-Bulkley model fitted much better. The present study would provide useful information for the reasonable application of AG and XG in making stable pesticide emulsion.     

Effects of paprika pigments on oxidation of linoleic acid stored in the dark or exposed to light

We examined the antioxidant effects of paprika pigments on oxidation of linoleic acid and on decoloration of the sample when stored at 37 degrees C in the dark or exposed to fluorescent light for 8 h per day. (1)H nuclear magnetic resonance with dioxane as an external proton reference was used to estimate the oxidative deterioration of linoleic acid. Oxidation was estimated by observing the ratio of the divinylmethylene proton signal area in linoleic acid vs the proton signal area in dioxane. The addition of paprika pigments suppressed the oxidation of linoleic acid during storage in the dark, and the effect was markedly increased with increasing concentrations (0.02, 0.2, and 2%). When the linoleic acid with added paprika pigments was exposed to light, only a slight suppression of oxidation was observed, and the color of the sample disappeared more rapidly than that in the dark. At the time of decoloration of the sample with added pigments, considerable oxidation of linoleic acid occurred. As the color change is due to degradation of the pigment, an increase in oxidation at the time of discoloration is consistent with the pigments functioning as antioxidants. The addition of alpha-tocopherol to paprika pigments stabilized degradation of the pigments by light. Although the addition of alpha-tocopherol to linoleic acid with added paprika pigments prolonged the decoloration of the sample under light, the prevention of oxidation under the light condition was not as effective as for the samples stored in the dark.     

Effect of partial replacement of gum arabic with carbohydrates on its microencapsulation properties.

Gum arabic solutions (10% w/v) were emulsified with soy oil at oil/gum ratios of 0.25-5.0. At oil/gum ratios <1.0, it was established that gum arabic could be partially replaced with a nonsurfactant carbohydrate. To assess different carbohydrates as replacers for gum arabic, emulsions and spray-dried emulsions of soy oil and mixed solutions (10% w/v) of gum arabic and a range of carbohydrate wall materials (oil/gum = 0.5) were prepared and analyzed. Maize starch and glucose were ineffective as partial replacers of gum arabic, but maltodextrins of various dextrose equivalence values (5.5-38) successfully replaced 50% of the gum arabic. The microencapsulation efficiency of the gum arabic/maltodextrin stabilized powders was further increased by increasing total solids of the feed to the dryer and by increasing the atomizer nozzle diameter.     

Effect of calcium on the oxidation of linoleic acid by potato (Solanum tuberosum var. Desiree) tuber 5-lipoxygenase

When the effect of calcium on the oxidation of linoleic acid by potato tuber 5-lipoxygenase (LOX) was investigated, it was seen to promote the enzyme's activity at pH values higher than the optimum pH of 6.3, resulting in an enzyme activation at alkaline pH. Kinetic analysis of calcium activation at different pH values revealed that the cation abolished the inhibition by high substrate concentration, which occurs in the absence of Ca(2+), thus leading to activation at high substrate concentration. Studies were conducted to investigate the influence of Ca(2+) on the physicochemical nature of the substrate and its effect on the LOX activity expression. It was concluded that the aggregation mode rather than the aggregation state of linoleic acid is responsible for potato 5-LOX changes.     

Effect of the degree of processing on soy oil conjugated linoleic acid yields

Photoirradiation processing can be used to rapidly synthesize conjugated linoleic acid (CLA) in large quantities in soy oil. The objective of this study was to evaluate the effect of the level of refining of soy oil on CLA yields and oxidative properties after photoirradiation. Crude, alkali-refined, alkali-refined bleached, and alkali-refined bleached and deodorized (RBD) soy oils were photoirradiated in a pilot-plant processing system for 12 h with 0.35% iodine catalyst at 47 degrees C. RBD soy oil gave the highest total CLA yield of 16.3% of total oil with 4.3% cis, trans- and trans, cis-CLA isomers. Oxidative stability as measured by weight gain during incubation at 64 degrees C showed that iodine decreased the induction time of soy oil samples by 2-4 days. Photoirradiation processing further decreased the induction time by 2 days as a result of loss of total tocopherols. Iodine addition increased the titratable acidity in all the samples of soy oil. However, the level of refining affects this increase of titratable acidity, and RBD soy oil was found to be the most stable. The study indicates that RBD soy oil was the most suitable candidate for photoirradiation processing. Thus, soy oil should be alkali-refined, bleached, deodorized, and then photoprocessed followed by a secondary adsorption step to remove the iodine catalyst to obtain a RBD CLA-rich soy oil.     

Formation of volatile compounds in model experiments with crude leek (Allium ampeloprasum Var. Lancelot) enzyme extract and linoleic acid or linolenic acid

Three continuous assays are described for lipoxygenase (LOX), hydroperoxide lyase (HPL) and alcohol dehydrogenase (ADH) in leek tissue. The catalytic activity of LOX showed significant difference (significance level 5%) between linolenic acid (9.43 x 10(-)(4) katals per kg protein) and linoleic acid (2.53 x 10(-)(4) katals per kg protein), and the pH-optimum of LOX was 4.5-5.5 against linoleic acid. The catalytic activity of HPL was statistically the same for 9-(S)-hydroperoxy-(10E,12Z)-octadecadienoic acid (1.01 x 10(-)(2) katals per kg protein) and 13-(S)-hydroperoxy-(9Z,11E)-octadecadienoic acid (7.69 x 10(-)(3) katals per kg protein). ADH showed a catalytic activity of 5.01 x 10(-)(4) katals/kg of protein toward hexanal. Model experiments with crude enzyme extract from leek mixed with linoleic acid or linolenic acid demonstrated differences in the amount of produced aroma compounds. Linoleic acid resulted in significantly most hexanal, heptanal, (E)-2-heptenal, (E)-2-octenal, (E,E)-2,4-decadienal, pentanol, and hexanol, whereas linolenic acid resulted in significantly most (E)-2-pentenal, (E)-2-hexenal, (E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, and butanol. Leek LOX produced only the 13-hydroperoxide of linoleic acid and linolenic acid.     

Eggplant lipoxygenase (Solanum melongena): product characterization and effect of physicochemical properties of linoleic acid on the enzymatic activity

Lipoxygenase (LOX) from eggplant (Solanum melongena L. cv. Belleza negra) was partially purified, and the products and kinetics of the enzyme were studied. Linoleic acid (LA) was the best substrate for this enzyme. Product analysis by HPLC and GC/MS revealed that, at its pH optimum (pH 7.0), the enzyme converted LA almost totally into the 9-hydroperoxy isomer, whereas the 13-hydroperoxy isomer was only a minor product. At this pH, the enzyme had K(m) and V(max) values for LA of 1.4 microM and 2.2 micromol min(-1) (mg of protein)(-1), respectively, when the monomeric form of LA was used as substrate. The dependence of eggplant LOX activity on the physicochemical properties of LA was also studied. Experiments revealed that LA aggregates were used more efficiently than monomeric LA as substrate. The apparent substrate cooperativity observed may be due to the different activities exhibited toward monomers and aggregates. This result can be interpreted as a substrate-aggregation dependent activity.     

Impact of physicochemical characteristics on the oxidative stability of fish oil microencapsulated by spray-drying

The aim of the present research was to identify principal parameters determining the oxidative stability of microencapsulated fish oil. Microcapsules were prepared by spray-drying using different types of n-octenylsuccinate-derivatized starch, gum Arabic, sugar beet pectin, sodium caseinate, and/or glucose syrup. Two principal components to classify the different microcapsules accounting for up to 79% of the variance were identified. The principal components were determined by physicochemical parameters reflecting the emulsifying ability of the encapsulant and the drying behavior of the parent emulsion. Microcapsules, which were identified by principal component analysis to be significantly different, exhibited a low stability upon storage, showing that the principal components and, thus, the underlying physicochemical parameters analyzed in the present study are correlated with core material stability.     

Production of silkworms with conjugated linoleic acid (CLA) incorporated into their lipids by dietary CLA

Silkworms with conjugated linoleic acid (CLA) incorporated into their lipids (designated CLA silkworms) were produced to enhance the quality of silkworms having a synergistic effect with CLA functions by dietary synthetic CLA. Silkworm larvae were fed fresh mulberry leaves (control diet) until the third instar stage and were then subjected to various levels (0%, 0.1%, 1%, 5%, and 10%) of CLA-sprayed mulberry leaves (designated CLA diet) beginning on the first day of the fourth instar stage and continuing to the third day of the fifth instar stage. CLA contents in CLA silkworms increased proportionally with increasing CLA levels of CLA diets. CLA silkworms on a 1% CLA diet contained 2.2 g CLA/100 g lipid without body weight reduction, whereas CLA silkworms on a 10% CLA diet contained 14.8 g CLA/100 g lipid with a significant reduction of body weight, relative to the control silkworms. The CLA content in the lipids of CLA silkworms on a 10% CLA diet was significantly higher than that of CLA silkworms on a 5% CLA diet. A 0.1% CLA diet was not sufficient to accumulate CLA in the silkworms. Most of the CLA (approximately 99%) of silkworm lipids was present in triglyceride (TG) with a similar ratio of c9,t11 and t10,c12 CLA isomers. These results suggest that a 1% CLA diet was suitable for the production of CLA silkworms.     

Production of conjugated linoleic acid (CLA) by Bifidobacterium breve LMC520 and its compatibility with CLA-producing rumen bacteria

This study was performed to characterize the ability of an active Bifidobacterium strain to produce conjugated linoleic acid (CLA) and to test its possible utilization as a probiotic compatible to the ruminal condition. Bifidobacterium breve LMC520 can actively convert linoleic acid (LA) to cis-9,trans-11-CLA, which is a major isomer derived from microbial conversion. LMC520 showed reasonable tolerance under acidic conditions (pH 2.5 with 1% pepsin) and in the presence of oxgall (0-3%). The growth and CLA production of LMC520 were tested under ruminal conditions and compared with those of Butyrivibrio fibrisolvens A38, which is a major CLA producer in the rumen as an intermediate in the biohydrogenation (BH) process. LMC520 converted 15% of LA to CLA under ruminal conditions, which was 2 times higher activity than that of A38, and there was no decline in CLA level during prolonged incubation of 48 h. The BH activity of LMC520 was comparable to that of A38. When LMC520 was cocultured with A38, even with slight decrease of CLA due to high BH activity by A38, but the level of CLA was maintained by the high CLA-producing activity of LMC520. This comparative study shows the potential of this strain to be applied as a functional probiotic not only for humans but also for ruminants as well as to increase CLA production.     

Changes in the fatty acid profile of the subcutaneous fat of swine throughout fattening as affected by dietary conjugated linoleic acid and monounsaturated fatty acids

The fatty acid profile of the subcutaneous fat of pigs and its evolution throughout fattening as affected by dietary conjugated linoleic acid (CLA), monounsaturated fatty acids (MUFA), and their interaction (CLAxMUFA) were studied. Three levels (0, 1, and 2%) of an enriched CLA oil (28% cis-9, trans-11 and 28% trans-10, cis-12 CLA) were combined with two levels of MUFA (low, 19% average; and high, 39% average) for pig feeding (288 gilts). Subcutaneous shot-biopsies were taken from 48 animals at the beginning of the trial (S1, 70 kg), 14 days later (S2, 80 kg), and at slaughter (S3, 107 kg). Inclusion of CLA in the diet caused an increase during fattening in cis-9, trans-11 CLA, trans-10, cis-12 CLA, and saturated fatty acids (SFA) contents of pig backfat and a decrease in MUFA and polyunsaturated fatty acids (PUFA). MUFA supplementation also led to a MUFA enrichment of backfat. The interaction CLAxMUFA affected the SFA content. The rates of accumulation of CLA isomers, SFA, and MUFA throughout the trial did not follow a linear behavior, such rates being higher from S1 to S2 than from S2 to S3. These rates were also influenced by dietary CLA and MUFA levels. The increase in the ratio of saturated to unsaturated fatty acids of backfat caused by dietary CLA might be balanced by supplementation of pig diets with MUFA.     

Measuring antioxidant efficiency of wort, malt, and hops against the 2,2'-azobis(2-amidinopropane) dihydrochloride-induced oxidation of an aqueous dispersion of linoleic acid

This paper presents a simple, convenient method for determining the efficiency of antioxidants in aqueous systems. Production of conjugated diene hydroperoxide by oxidation of linoleic acid in an aqueous dispersion is monitored at 234 nm. 2, 2'-Azobis(2-amidinopropane) dihydrochloride is used as a free radical initiator. Among 12 antioxidants tested, phenolic compounds proved to be the most efficient, both kinetically and in terms of the inhibition time (T(inh)). Applied to wort, malt, and hops, the method confirmed a significant antioxidant activity in such products, especially hops. This assay can be used to follow oxidative changes throughout the brewing process and to understand the contribution of each raw material.     

Suppressive effect of rice bran incorporation in paddy soil on germination of Monochoria vaginalis and its relationship with electric conductivity

Laboratory experiments were conducted to investigate (1) the effects of the addition of rice (Oryza sativa. L.) bran to paddy soil on the germination of Monochoria vaginalis (Burm. f.) Kunth, and (2) the relationship between the electric conductivity (EC) of the soil solution and germination. Soil samples were collected at 4 sites in Japan. After flooded soils with rice bran had been incubated for 7?d at 30°C, the soil solution was collected using a porous cup and the EC of the soil solution was measured. The amounts of rice bran added to the soil were 0%, 0.3%, 0.6% and 0.9% (weight(w)/w). In the soil solution obtained, seeds of M. vaginalis were incubated for 3?d at 30°C, and the germination percentage was then analyzed. The addition of rice bran suppressed germination, and the degree of suppression increased with increasing content of rice bran. Although the same amount of rice bran was applied to each soil, the degree of growth suppression by rice bran as well as the EC of the soil solution differed among the soils. In each soil, there was a positive correlation between the amount of rice bran and EC, and the degree of growth suppression significantly increased with an increase in EC. When EC was higher than 150?mS?m^?1, seeds of M. vaginalis hardly germinated. There was no significant correlation between the oxidation-reduction potential (Eh) of soil and seed germination, suggesting that EC is a more reliable and convenient indicator than Eh for evaluating the relationship between the addition of organic material and seed germination. In conclusion, the addition of rice bran to soil increases the EC of the soil solution, and EC is one of the factors that suppress the germination of M. vaginalis. The suppressive effect of rice bran on germination is different among soils. This fact is attributed to the difference in EC due to the addition of rice bran. Thus, it is expected that EC can be used as an indicator for determining how much rice bran to add.     

Comparison of different methylation methods for the analysis of conjugated linoleic acid isomers by silver ion HPLC in beef lipids

Four different methods for the methylation of conjugated linoleic acid isomers (CLA) in ruminant lipids were compared by silver ion (Ag+) HPLC. The combination of base-catalyzed methods followed by an acid-catalyzed method with BF3/MeOH was tested under different temperatures (room temperature and at 60 degrees C), along with based-catalyzed methylation with NaOCH3 and methylation with BF3/MeOH after saponification with NaOH. The comparison among these four methods was done on muscle and adipose tissue samples from bulls. The repeatability theta of the combined base- and acid-catalyzed methylation (NaOCH3/BF3) at ambient temperature for 20 min and at 60 degrees C for 10 min was most suitable for the quantitative Ag+-HPLC analysis of CLA isomers. At 60 degrees C the combined methods supplied the highest concentrations of most CLA isomers. The base-catalyzed methylation and the saponification followed by BF3/MeOH methylation for 5 min generated significantly lower concentrations for most CLA isomers compared to the combined methods.     

The effect of oxidation by periodate on soil carbohydrate derived from plants and microorganisms

It has previously been shown that treatment of soil with periodate and tetraborate releases much of the carbohydrate and destroys an equivalent proportion of the soil aggregates. The residual carbohydrate is proportionately richer in glucose, arabinose and xylose, sugars characteristic of plant remains, than the whole soil. The effect of sodium periodate (0.02 M, 6–168 h) and sodium tetraborate (0.1 M, 6 h) treatment of soil on carbohydrates of different origin was examined using ¹⁴C-labelled soil in which the label was present in microbial products arising from 7 and 28 day incubations of ¹⁴C-glucose in soil, or in both plant and microbial materials resulting from 12 week incubations of ¹⁴C-labelled barley leaf and 1 year incubations of ¹⁴C-labelled ryegrass in soil. Arabinose and xylose were the sugars most resistant to periodate in the glucose incubated soil; in the ryegrass incubation arabinose, xylose and glucose were more persistent than galactose, mannose and rhamnose. In the barley leaf incubation arabinose was more persistent than galactose and rhamnose. Thus periodate oxidation did not distinguish between sugars of different origin in soil and it was concluded that in the case of arabinose and xylose the persistence related to differences in chemical structures rather than to physical factors such as particle size of the plant fragments. The composition of the more stable residue can therefore not be used as an indication of polysaccharide origin in any comparison of the relative effects of plant and microbially derived material as aggregating agents.     

Antioxidant properties of crocin from Gardenia jasminoides Ellis and study of the reactions of crocin with linoleic acid and crocin with oxygen

Crocin-a water soluble carotenoid-is found in the fruits of gardenia (Gardenia jasminoides Ellis) and in the stigmas of saffron (Crocus sativus Linne). For crocin purification, gardenia fruits are extracted with 50% acetone, followed by ether washing, ion exchange, and separation by preparative HPLC. Purified crocin with purity of >99.6% has an antioxidative activity at concentrations up to 40 ppm. At 20 ppm the antioxidative activity of crocin is comparable to that of BHA. The antioxidant property of crocin as evaluated by the thiocyanate method was better than with the thiobarbituric acid method. The adduct between the linoleic acid radical and crocin was detected by LC-MS. When crocin reacted with oxygen in the presence of FeSO(4), intermediates such as monohydroperoxides and dihydroperoxides of crocin were formed and detected by LC-MS.