This study was conducted to observe the effect of trace amounts of various ions CuSO4, FeSO4, ZnSO4 and MgSO4, on the microstructure of bovine serum albumin (BSA) gels. Microstructure was studied using transmission and scanning electron microscopy. Protein dispersions (5% w/v) were made in 0.1 M NaCl containing 5 mM of each of the divalent cations. The pH was adjusted to pH 7 using 0.1 N NaOH. Addition of CuSO4 markedly changed the microstructure of BSA gels; significantly larger water entrapping void spaces were seen and the gel matrix comprised of larger aggregates. An opposite effect was seen for MgSO4 which gave compact gels with significantly smaller gel matrix forming protein aggregates and void spaces. Trace amount of minerals impacting microstructure of gels as observed in this study has dramatic functional implications. This is because the aggregate size determines whether the gel is opaque or transparent and the degree of water entrapment effects texture.
Factors affecting the rheological properties and stability of ethanol-in-oil (E/O) emulsion were studied. Emulsions prepared with lower ethanol concentration exhibited higher apparent viscosity, smaller droplet size and narrower droplet size distribution. However, decreasing ethanol concentration may cause a reduction in the amount of emulsified ethanol, facilitating partial separating out of ethanol. The effect of the degree of polymerization of polyglycerol esters of oleic acid on E/O emulsions was investigated with decaglycerol esters of oleic acid (MO-750), hexaglycerol esters of oleic acid (MO-500), and tetraglycerol esters of oleic acid (MO-310). The efficiencies of the emulsifying agents were evaluated by measuring their interfacial activity and ability to stabilize E/O emulsions. Although no significant differences in the interfacial tension values were recognized, the stability of the emulsions increased with the degree of polymerization of the emulsifying agent. Besides sunflower oil, soybean oil and olive oil can also be used to prepare stable E/O emulsions. The characteristics of the emulsions were determined.
Moisture migration in deep-fried food was investigated during frozen storage with regular temperature cycling for defrosting. The increase in moisture content of the coating and the change in water vapor weight in the package suggest that moisture from the filling migrated directly to the coating during frozen storage. Classification of the water in the filling by differential scanning calorimetry revealed that free water formed by the temperature cycling was transferred mainly from the filling to the coating. It was found that this decrease in the free water of the filling helped maintain the quality of frozen deep-fried food.
The force-deformation curve of bulk soybean fermented with Rhizopus could be described by the equation, F=C(Δe)n. The degree of maceration of fermented soybean (a measure of softness) was estimated by the n-value of the power of the equation and depended on the Rhizopus strain used. Of the Rhizopus strains tested, R. oligosporus TISTR3001 (well known as a dominant tempeh processing species) and Rhizopus sp. LKN (isolated from a tempeh starter) gave high degrees of maceration corresponding to n=1.3 (initial value of 1.8) and 1.6 (initial value of 1.8) respectively, for 60 h of fermentation of raw soybeans at 30°C. On the other hand, the R. oligosporus TISTR3001 and Rhizopus sp. LKN for sterilized soybeans decreased to n-values of 1.5 from initial value of 1.7 and to 1.3 from initial value of 1.7, respectively, for 60 h of fermentation at 30°C. n-Values less than 1.5 were considered to indicate a considerably high degrees of maceration.
In order to study the influence of the vacuum evaporation (VE) process on the functionality of whey protein concentrates (WPC’s) , Cheddar WPC’s were produced with and without VE, viz. by i) ultrafiltration (UF) and spray drying (SD) (UFSD), and by ii) UF, VE and SD (UFVESD). Geling properties and interfacial microstructure around residual fat were studied by transmission electron microscopy. Both WPC’s were hydrated with 0.1 M NaCl at pH 7.0 (10% protein w/v) and gels were made in glass tubes by heating for 15 min at 90°C. Electron dense membrane like structures were seen at the oil-water interface of gels prepared with UFVESD whey implying the presence of large amphipathic aggregates. Samples from UFSD which had not been subjected to VE, did not show such structures. Gels made from UFVESD had significantly higher strain values than UFSD gels. Functional attributes studied were packing density (PD) and water holding capacity (WHC). The packing density of the UFVESD powders was three times that of the UFSD powders indicating markedly larger powder particles. Data thus indicated changes in the interfacial microstructure and some functional attributes due to the incorporation of VE.
The objective was to determine the effect of a peptide sweetener, Aspartame, compared to a carbohydrate sweetener, sucrose, on the microstructure of yogurt. Microstructure was determined by transmission and scanning electron microscopy. Without the sweeteners, casein micelles, that make up the yogurt matrix, were observed in single longitudinal polymers. When Aspartame was used, casein micelles formed double longitudinal polymers. In comparison sugar caused casein micelles to form clusters. Data show that type of sweetener impacts state of association of casein micelles and thus effects microstructure.
The oxidation processes of linoleic acid encapsulated with gum arabic or maltodextrin at various weight ratios by spray-drying were analyzed using the model in which the free energy of activation for the rate constant of the autocatalytic type kinetics was assumed to obey a Gaussian distribution. The model could well express the oxidation processes, and the rate constant corresponding to the mean value of the free energy of activation, k, was greater for linoleic acid encapsulated at the higher weight ratio. Emulsions of linoleic acid and maltodextrin solution with different diameters were spray-dried to prepare the microcapsules. The oxidation processes of linoleic acid within the microcapsules were also calculated using the model. The k value was smaller for the emulsion with a smaller diameter.
Wheat grains were milled into 8 fractions ranging from the surface layer to the center of a grain with a modified machine used for polishing brewers’ rice. The classified wheat flours were ground to the size of starch, and the moisture content in each fraction was about 12%. The ash, lipid, protein and dietary fiber contents decreased from the surface to the center, while sugar content increased. Potassium, sodium, magnesium, calcium and manganese, but not copper contents also decreased from the surface to the center. Large, medium and small granule starches were isolated from these classified wheat flours. From the surface to the center, the percentage of large granules decreased, small granules increased, and medium granules remained approximately constant. The ratio of water-soluble and NaCl-soluble proteins decreased from the surface to the center, whereas that of n-propanol-soluble and lactic acid-soluble proteins increased.
Wheat grain was divided into eight fractions ranging from the surface layer to the center with a machine used to polish brewers’ rice. Large, medium and small granule starches were isolated from the wheat flour, and their physicochemical properties were investigated. Moisture sorption showed a negative correlation to granule size. The starches had A-type X-ray diffraction patterns typical of cereal starches. The amylose content, the relative crystallinity and the enthalpies of gelatinization decreased in the order of large, medium and small granules in each fraction. The enthalpies showed a positive correlation to the relative crystallinity.
A microbe of Pseudomonas syringae pathovar cannabina SF 4-17 converting 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFA) was isolated from the soil. When HMF was incubated with this microbe for 1 day, the absorbance at 283 nm, the absorption maximum of HMF, decreased by 99%. This microbe also decomposed furfural by about 97%, but not 2-furancarboxylic acid or acetylfuran. After food samples with added 0.01% HMF were incubated with P. syringae SF 4-17, the amount of HMF in each sample was estimated from the absorbance at 283 nm before and after cultivation. The amounts of HMF of heated orange juice and caramel were estimated to be about 2 mg% and 900 mg%, respectively.
Moisture content, total lipid content, lipid classes, fatty acid composition and sugar composition were used to express quality characteristics of macadamia nuts. These parameters of the dry nuts were determined during a peak harvest season in 1999, and the quality parameters were compared with those of nuts rejected by a nut processor. Moisture content of rejected nuts showed significantly higher value than that of acceptable nuts (p<0.05). There is a significant difference between acceptable and rejected nuts in total lipid content (p<0.05), and the total lipid content of acceptable nuts gradually increased towards the end of the peak harvest season. The rejected nuts exhibited total lipid contents of 60% and moisture content of 1.96% wet basis (w.b.), while the acceptable ones showed total lipid content of more than 63% and moisture content less than 1.42% w.b. The sugar composition of the rejected nuts was also remarkably different from the acceptable nuts, and the former had higher sucrose content than the later. Fructose and glucose contents showed a similar tendency but with smaller magnitude. These results clearly indicate that the rejected nuts are poor in quality, which may lead to shorter shelf life, harder texture and bitter taste. Lipid classes were also identified and the major neutral lipid was triacylglycerols, which accounted for more than 73%. The lowest content of triacylglycerols was observed in the rejected nuts and no remarkable differences were noted from other lipid classes. Fatty acid composition determined in the present paper agreed with published data and showed the major acid to be oleic acid (> 55%), followed by palmitoleic acid (> 28%). The rejected nuts contained more saturated fatty acids: palmitic, stearic and arachidic acids, and a remarkably low content of palmitoleic acid (p<0.05). The ratio of unsaturated to saturated fatty acids for the acceptable nuts was higher than that in the rejected nuts.
Hot-water extracts from the muscle of yellowtail Seriola quinqueradiata were analyzed for low-molecular-weight substances and organic taste-active components were identified by sensory tests (omission and addition tests). Free amino acids, adenine nucleotides, creatine, lactic acid, and inorganic ions (Na+, K+, Cl−, and PO43–) were abundant in the muscle extract. In the reconstituted extract prepared on the basis of the analytical data, the following substances were identified as the organic taste-active components by the sensory test: free amino acids (glutamic acid, α-aminobutylic acid, α-aminoadipic acid, β-aminoisobutyric acid, γ-aminobutyric acid, and histidine) and a nucleotide IMP.
Pectic polysaccharides in cherry tomato fruits (Pepe) have been studied at three stages of ripening (immature-green, mature-green, and mature-red). The alcohol-insoluble solids obtained from the fruits were fractionated into four groups of pectic polysaccharides: water-soluble pectin (WP), hexametaphosphate-soluble pectin (PP), HCl-soluble pectin (HP), and KOH-soluble pectin (KP). The content of total pectic polysaccharides decreased with ripening of the fruits; especially, the main fraction HP at immature-green stage hardly existed at the mature-red stage. Instead, the content of WP increased with maturation. The pectic polysaccharide fractions were analyzed by gel-filtration, and the molecular weight of each fraction decreased with ripening. This phenomenon was accompanied by an increase in the activities of the pectin-hydrolyzing enzymes, polygalacturonase and pectinesterase. These results indicate that the softening of cherry tomato fruits during the ripening may depend on degradation and depolymerization of pectic polysaccharides by the pectin-hydrolyzing enzymes.
Eight-month-old male Sprague Dawley rats were fed diets containing α-tocopherol (Toc) or tocotrienol (T3) mixture (composed of 20.5% α-Toc, 21.4% α-T3, 36.5% γ-T3 and other analogs) at the 0.1 or 0.5% level for 3 weeks to examine their dietary effects on lipid metabolism and immune indices. Feeding of α-Toc and T3 significantly de-creased liver phosphatidylcholine peroxide and serum phospholipid levels. In the regulation of immunoglobulin level, significant increase in serum IgA level was observed in the rats fed α-Toc or T3, but the effect on immunoglobulin productivity from spleen and mesenteric lymph node (MLN) was not as marked. Feeding of α-Toc and T3 significantly decreased LTB4-releasing activity of peritoneal exudate cells without decreasing arachidonic acid level. The suppression of LTB4 release was more marked in the rats fed 0.1% α-Toc or T3 than in these fed them at the 0.5% level. When animals were killed after 10 h of fasting, T3 was detected only in MLN and epidydimal adipose tissue. These results suggest that T3 modulates lipid metabolism and immune functions as well as α-Toc, and that MLN and adipose tissue are the main target tissues of T3.
Cultured leaf cells of Nyoho strawberry (Fragaria ananassa Duch.) produced 4 times more anthocyanins than fruit, with additions of 2.0 mg/l of 1-naphthalenacetic acid (NAA) and 0.2 mg/l of benzyladenine (BA) for 2 weeks. They were habituated after 6 passages at NAA 1.25 and BA 0.125 μg/l in 107 cultures with stepwise decrease of the additions at 2-week intervals, and supervention of a gradual decrease in anthocyanin contents of 80%. They fully recovered through the following 43 passages without the additions. Finally, 3 types of cell line rich in cyanidin 3-glucoside (62%), peonidin 3-glucoside (55%) or both (49 and 36%, respectively) were obtained. They also produced pelargonidin 3-glucoside (0.6 to 1.8%), which was the main component in the fruit. The fruit produced peonidin 3-glucoside (0.4%), as well as pelargonidin 3-O-(6-O-malonyl-β-D-glucoside) and cyanidin 3-glucoside. The habituation seems to have caused some activation or inhibition of the cell’s anthocyanin formation, which originated from the mother plant.
Sodium gluconate (Na-gluconate) and potassium gluconate (K-gluconate) were used as NaCl substitutes in breadmaking to determine their potential usefulness in preparing reduced-sodium bread and non-sodium bread. Replacement of 75% of the NaCl by Na-gluconate and of 50% by K-gluconate had no effect on rheological properties of dough as measured by Brabender Extensograph. Replacement of 100% of the NaCl by either Na-gluconate or K-gluconate resulted in decreased resistance to extension, but the decreased resistance to extension had no effect on dough handling properties. Expansion of white bread dough (5% sugar, flour weight basis) increased with the proportion of NaCl replaced by Na-gluconate or K-gluconate. The patterns of carbon dioxide production during fermentation of non-sugar bread dough showed that as the proportion of Na-gluconate or K-gluconate increased, the time required to complete fermentation decreased, and the fermentation pattern showed a gradual resemblance to that seen in non-sugar bread dough without NaCl. In white bread, complete replacement of NaCl (2%, flour weight basis) by Na-gluconate or K-gluconate did not cause a difference in loaf volume, nor did it have any significant effect on overall desirability. Shelf life of white bread was not affected by substitution of Na-gluconate or K-gluconate for NaCl. Based on these results, it is possible to make reduced-sodium bread using Na-gluconate, and non-sodium bread using K-gluconate, incorporating each gluconic acid salt in an amount equal to 1.8% of flour weight in white bread.
Whole quinoa grain was separated into bran and milled grain, and the milled grain into perisperm and embryo. The proximate composition of the milled grain was similar to that of whole grain. The protein and lipid content of the embryo was 57% of total protein and 49% of total lipid, respectively. Mineral analysis showed that the quinoa grain was rich in K, Mg, Ca, P and Fe. The perisperm contained large oval starch aggregates 20–30 μm in diameter and polygonal granules around 1 μm in diameter. Differential scanning calorimetry data indicated a gelatinization temperature of 54.0 to 71.0°C and enthalpy of 11.0 J/g starch. The water-soluble protein and NaCl-soluble protein fractions composed 28.7–36.2% and 28.9–32.9% of total protein in each fraction. Unsaturated fatty acid accounted for 87.2–87.8% of total fatty acid. Phytate, a trypsin inhibitor activity and lipoxygenase activity in the embryo were highest. The saponin content of the bran was 86% of total saponin.
Anthocyanin pigments (AN) extracted and purified from purple sweet potatoes (Yamagawamurasaki and Kankei 55) were studied for stability during alcoholic fermentation. The fermentation was continued for 7 days, followed by aging up to day 120. Analyses were performed to measure pH, sugar and alcohol contents, browning, relative absorbance at 525 nm, and hue, individual AN and alcohol by high-performance liquid chromatography (HPLC). Up to day 7 of fermentation: 1) pH decreased slightly; 2) browning increased; 3) absorbance increased; 4) the hue of Yamagawamurasaki AN underwent a positive shift in terms of both a* and b* values, taking on a deeper red color, and the Kankei 55 AN had a positive shift for a* values but no shift for b* values; 5) The structures of the major ANs of purple sweet potato were estimated as follows: A:3-O-(2-O-(6-O-caffeoyl [Caf]-β-D-glucopyranosyl [Glu]))-β-D-Glu-(5-O-(β-D-Glu))cyanidin [Cy], B:3-O-(2-O-(6-O-Caf-β-D-Glu))-(6--Caf-β-D-Glu)-(5-O-(β-D-Glu))Cy, C: 3-O-(2-O-(6-O-Caf-β-D-Glu))-(6-O-p-Hydroxybenzoyl [p-HB]-β-D-Glu)-(5-O-(β-D-Glu))Cy, D: 3-O-(2-O-(6-O-Caf-β-D-Glu))-β-D-Glu)-(5-O-(β-D-Glu))peonidin [Pe], 3-O-(2-O-(6-O-Caf-β-D-Glu))-(6-O-feruloyl [Fer]-β-D-Glu)-(5-O-(β-D-Glu))Cy, 3-O-(2-O-(6-O-Caf-β-D-Glu))-(6-O-Caf-β-D-Glu)-(5-O-(β-D-Glu))Pe, 3-O-(2-O-(6-O-Caf-β-D-Glu))-(6-O-p-HB-β-D-Glu)-(5-O-(β-D-Glu))Pe, 3-O-(2-O-(6-O-Caf-β-D-Glu))-(6-O-Fer-β-D-Glu)-(5-O-(β-D-Glu))Pe. 6) Compared to pre-fermentation values, both HPLC peak area of Yamagawamurasaki AN and Kankei 55 AN rapidly decreased became unstable on day 7 of fermentation. After the fermentation, major ANs aged were stably.
We compared cv. Mochiminori as glutinous rice and cv. Koshihikari as non-glutinous rice using light transmittance photography and clarified that the maximum hollow width/grain width ratios at the hollow (hollow ratio) of Mochiminori and Koshihikari were different. The Mochiminori rice grain had a small hollow ratio or undetectable internal hollows, but the Koshihikari had a large hollow ratio. This agreed with the result by nuclear magnetic resonance micro imaging. In addition, grains from mixed cooking of the two cultivars were identified as Mochiminori or Koshihikari rice using light transmittance photography instead of the iodine dyeing method. The remaining iodine solution and the dyed grain samples were post-treated safely, because the iodine is toxic. Light transmittance photography easily discriminated Mochiminori or Koshihikari rice grains.
The present study was carried out to clarify the dietary effect of pectin on imunoglobulin (Ig) and cytokine production of rat lymphocytes. Rats were fed a diet containing 0 (cellulose) and 1, 2 or 5% levels of pectin for 2 weeks. Dietary pectin, as compared with cellulose, enhanced production of IgA, IgG and IgM by mesenteric lymph node lymphocytes, while reducing IgE production. In the lymphocytes obtained from the rats fed pectin, interferon-γ production and interleukin-2 receptor expression were significantly higher than in those from the rats fed cellulose. These results suggest that the effect of dietary pectin was exerted through the functioning of Th 1 cells. In this context, dietary pectin was expected to alleviate the type 1 allergy reaction.
Polyphenol oxidase (PPO) is transported to plastid after translation. However, we often detect PPO activity in a soluble fraction of apple. Here we examined the location of PPO in retail apples. PPO activity was detected primarily in the plastidal fraction in most apples, however, it was sometimes detected more strongly in the soluble fraction than in the plastidal fraction. Western blotting analysis detected PPOs in both plastidal and soluble fractions as the same band. Some apples having high soluble PPO activity showed a band of decomposed PPO in addition to an intact band. Plastidal, soluble, and solubilized PPOs had similar optimal pH at about 4 and Km values (about 100 μM). However, solubilized PPO showed the highest Vmax and soluble PPO the least value. Some part of PPO seems to be solubilized, denatured and proteolyzed during maturation and storage.
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