Most of the published methods for estimating temperature history during heating/cooling/freezing solid food require data on thermal properties of the product and any relevant heat transfer coefficients. However, there are some difficulties of obtaining thermal data for use in industrial heating/cooling/freezing of food. In this paper the development of a new procedure for estimating the temperature history is briefly reviewed, a procedure which does not require the knowledge of thermal data of the food being heated/frozen. This procedure collects a series of time/temperature data at a point in the food in the early stages of heating/freezing, analyzes these data to predict the thermal parameters which are responsible for heat conduction, and predicts the time/temperature relationship for the remainder of the heating/cooling/freezing phases.
The enzymatic degradation of sodium alginate was continuously carried out to effectively produce alginate oligosaccharides using immobilized alginate lyase in a CSTR (continuous stirred tank reactor) system. The alginate lyase was immobilized onto the chitosan beads and the reaction was operated at an initial alginate concentration of 10 g l−1 at 35°C and pH 7.0 under the dilution rate of 0.77 to 1.74 h−1. The degradation products mainly consisted of di-, tri-, tetra-, penta-, and hexasaccharides with the highest conversion of 0.34, with the volumetric production rate of the total oligosaccharides dependent on the dilution rate. The production process was mathematically modeled from the basic material balance and the rate equation, and showed agreement between the simulated and experimental results. The present reactor system was found to be effective for obtaining alginate oligosaccharides with a high production rate.
Okara is a by-product of tofu and soybean protein production. Okara contains 80-85% moisture. The dehydration of okara is very difficult with the conventional method. In the present work, okara was dehydrated with a compression instrument (0.49 MPa) using calcium chloride. About 65% water content, on a wet basis, could be obtained with the addition of calcium chloride at levels higher than 0.01 g/g of wet okara. The water content of the dehydrated okara correlated with the pH of the dehydrated solution obtained by dehydration with calcium chloride. With 2% calcium chloride solution, water contents less than 67% could be obtained during four repeated dehydration cycles.
A pilot plant, with immobilized β-galactosidase (IMG) in a plug flow reactor, was established to prepare whey syrup from cheese whey. The effects of space velocity and lactose concentration on the initial rate of lactose hydrolysis (IRLH) and the operational temperature effect on the half-life and productivity of IMG were investigated. When the space velocity of whey was controlled at 0.6 l/(l·min), consolidation and channeling did not occur in the pilot plant. A better IRLH was obtained when the whey had high lactose concentration. With an increase in operational temperature in the pilot plant, the IRLH was increased. However, the half-life of IMG was shortened, as a result, the productivity of IMG decreased. The best temperature was 10°C for the operation of the pilot plant. The plant could be operated for as long as 50 days at 10°C if the IMG is washed by sterilized deionized water for 1 h each day. When the IRLH decreases to 10%, the IMG is treated by phosphate buffer solution (0.01 M, pH 6.4) and tetramethylammonium chloride solution (0.03%, pH 2.5) for 30 min, respectively. These results show that the developed pilot plant had prospects in the dairy industry because it could be operated continuously for a long period, the washing and sterilization were simple, and the rate of lactose hydrolysis (RLH) was more than 80% in the whey syrup.
Seven phenolic compounds, vanillic acid (1), threo-guaiacyl glycerol (2), erythro-guaiacyl glycerol (3), taxifolin (4), dihydrodehydrodiconiferyl alcohol (5), dihydrodehydrodiconiferyl alcohol-9-O-β-D-glucoside (6) and dihydrodehydrodiconiferyl alcohol-(4→8)-erythro-guaiacyl glycerol ether (7), were separated from the methanol extract of Viticis trifoliae Fructus (Fruit of Vitex rotundifolia L.) and their structures were identified on the basis of spectroscopic data. In addition, 1, 2, 4-7 and two previously isolated iridoid glucosides, agnuside (8) and VR-I (10-O-vanilloyl aucubin) (9) were tested for antioxidative activity using the ferric thiocyanate method. These compounds, except 8, exhibited stronger antioxidative activity than 3-tert-butyl-4-hydroxyanisole. Moreover, 1, 2 and 4-9 were investigated for the scavenging effect on 1,1-diphenyl-2-picrylhydrazyl. All tested compounds, except 8, showed a potent scavenging effect. Especially, the effect of 4 was almost twice that of α-tocopherol at a concentration of 0.02 mM.
When cream puff paste (CPP) was baked after it was kept at 35°C for 3 h, it did not puff up as much as one baked just after preparation of the CPP. The optimum preparative method for CPP with the least deterioration during storage was found by carrying out random centroid optimization regarding 9 factors, such as the ratio of flour, shortening, yolk, egg white and water as ingredients, and the heating time at the first stage, the temperature of the heated mixture of water, shortening, and flour on the addition of the egg solution, and the time and temperature of the incubation of the yolk as preparative conditions. The optimum values of 18.0%, 14.7%, 13.4%, 25.4%, 28.5%, 106.5s, 53.9°C, 46.7 min, and 63.7°C were obtained, respectively. Each value except the time and temperature for incubating the yolk was similar to that in the standard preparative method of CPP, which brought about deterioration during storage. The incubation of the yolk at 63.7°C for 46.7 min caused a decreased in the specific activity of amylase in the yolk from 1.71±0.43 to 0.20±0.17 μg of maltose/mg of protein but did not affect proteins in the CPP.
The effects of lemon juice and its crude flavonoids on blood pressure were examined using spontaneously hypertensive rats (SHR). The 5% diluted lemon juice was orally administered in the diet to SHR, and they tended to have a lower systolic blood pressure than the control rats after 90 days. The systolic blood pressure of SHR fed a diet containing crude flavonoids from the juice for 16 weeks was significantly lower than that of the control group (p<0.05). The systolic blood pressure with administration of fraction B, which was fractionated from the crude flavonoids, was significantly lower (p<0.05) after 4 weeks. The crude flavonoids and fraction B contained abundant flavonoid glycosides of eriocitrin, hesperidin, and 6,8-di-C-β-glucosyldiosmin as determined by high performance liquid chromatography (HPLC) analysis. The crude flavonoids and the flavonoid glycosides had an inhibitory effect on angiotensin I converting enzyme (ACE).
The effects of pepsin treatment on the gelation of porcine globin were studied by measurements of surface hydrophobicity, extent of hydrolysis, gel strength and polyacrylamide gel electrophoresis. Gel formation occurred below pH 4.0 at 30-50°C above 3% globin concentration. After 48-h incubation at pH 3.0 and 50°C in the pepsin concentration used (0.005-1.0% (E/S)), 0.01% (enzyme-substrate ratio: E/S) pepsin gave the highest gel strength. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed several peptides with molecular weight of 4000-6000 to be present in the resultant gel after 48 h of pepsin treatment. Gel strength after 12-h incubation was highly correlated with surface hydrophobicity and markedly elevated at 2-3% hydrolysis. As longer incubation time (over 12 h) is required for maximum gel strength, the gelation of globin would thus appear to occur as follows: pepsin yields peptides from globin, which aggregate to produce a three-dimensional gel network during incubation.
Peptic globin digest (PG) was prepared from porcine blood globin, and the peptides were characterized by separation processes such as gel filtration chromatography, hydrophobic chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Aggregation of the peptides was indicated by high-performance liquid chromatography (HPLC). Two fractions (F1 and F2) were obtained from PG by gel filtration chromatography. Hydrophobic chromatography of fraction F1 was carried out, and a peak corresponding to the aggregate was found in fractions F1b-F1e. These fractions, which showed an aggregate peak by HPLC, were subjected to SDS-PAGE, and two major peptide bands with molecular weight of 5000 and 6000 were found. Amino acid sequence indicated the N-terminal amino acid of these peptides to be 42-47 (Phe-Asp) and 86-92 (Ala-Leu) of β-globin, respectively. Furthermore, it was predicted that the Mw 5000 and 6000 peptides may possibly be 42-85 (Mw 4749) and 86-141 (Mw 6117) of β-globin, respectively, based on the specificity of pepsin.
We investigated the antioxidative flavonoid glycosides in the peel extract of lemon fruit (Citrus limon). Six flavanon glycosides: eriocitrin, neoeriocitrin, narirutin, naringin, hesperidin, and neohesperidin, and three flavone glycosides: diosmin, 6,8-di-C-β-glucosyldiosmin (DGD), and 6-C-β-glucosyldiosmin (GD) were identified by high-performance liquid chromatography (HPLC) analysis. Their antioxidative activity was examined using a linoleic acid autoxidation system. The antioxidative activity of eriocitrin, neoeriocitrin and DGD was stronger than that of the others. Flavonoid glycosides were present primarily in the peel of lemon fruit. There was only a small difference in the content of the flavonoid glycosides of the lemon fruit juice from various sources and varieties. Lemon fruit contained abundant amounts of eriocitrin and hesperidin and also contained narirutin, diosmin, and DGD, but GD, neoeriocitrin, naringin, and neohesperidin were present only in trace amounts. The content of DGD, GD, and eriocitrin was especially abundant in lemons and limes; however, they were scarcely found in other citrus fruits. The content of flavonoid compounds in lemon juice obtained by an in-line extractor at a juice factory was more abundant than that obtained by hand-squeezing. These compounds were found to be stable even under heat treatment conditions (121°C, 15 min) in acidic solution.
Micellar electrokinetic chromatography (MEKC) methods were developed for analyzing crocin and crocetin yellow gardenia pigments, and geniposide and gardenoside in gardenia fruits. Crocin and crocetin pigments were successfully separated by MEKC with a 20 mM SDS solution in 50 mM phosphate buffer (pH 7.0) containing 20% acetonitrile and another MEKC method with a 20 mM ammonium formate buffer (pH 7.0) containing 2.0% butyl acrylate/butyl methacrylate/methacrylic acid copolymer sodium salts (BBMA). Geniposide and gardenoside were also successfully separated by MEKC with a 20 mM sodium dodecyl sulfate (SDS) solution in 30 mM borate buffer (pH 8.5). The crocin and crocetin yellow pigments were extracted from food samples (candies and noodles) by solid-phase extraction cartridges and analyzed by MEKC with SDS. The geniposide and gardenoside in gardenia fruits grown in different habitats were determined by the developed technique.
To examine the influence of the maturity of ume fruit (Japanese apricot, Prunus mume SIEB. et ZUCC.) on the taste of ume liquor, we analyzed various taste components, pectic substances and cyanogenic glycosides in the liquor aged for three months and the corresponding fruit material picked on six different occasions between May 14 and July 1. We also evaluated the bitterness, aroma and taste of the liquor according to a 5-level numerical scale. The following results were obtained: (1) The liquor made from ume fruit picked after June 11 exhibited a slight increase in red and yellow color along with a delay in the harvesting date, and the lightness gradually decreased. (2) Organic acid composition in the liquor changed with almost the same tendency as that of the fruit material. (3) Ume liquor made after June 11 easily exhibited inversion of sucrose to glucose and fructose, and the sugar penetrating into the flesh of the fruit during aging inverted to structural sugars easier than that in the liquor. (4) Total pectin level in ume fruit removed from the liquor and the corresponding fruit material was not greatly different. (5) Amygdalin was barely detectable in the liquor. The ume liquor made on May 14 contained 69.0 mg prunasin in 1000 ml liquor, but this gradually decreased with the picking time of the fruit material occurring late. (6) The evaluation score of the sensory test for bitterness gradually decreased in accompaniment with a delay in the picking time of the fruit material, and that for aroma and taste increased little by little. The scores of sensory test for bitterness and prunasin levels showed a correlation at r=0.83 (p<0.05). From these results, we would like to propose that the fruit reaped at ripe or over-ripe stages is the optimum material for ume liquor because the liquor produced from such fruit barely exhibits bitterness and is favorable in aroma and taste.
Modifications of the standard Ames test and umu test were employed to study the “desmutagenic” response exerted by pheophytin b against the mutagenicity of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The mixture from which pheophytin b separated was activated with S9 mix and was assayed to determine the remaining mutagenicity of Trp-P-2. The decrease in the His+ revertant colonies of Salmonella typhimurium TA98 was dependent on the increase in pheophytin b concentrations. Binding of Trp-P-2 to DNA and the subsequent induction of the SOS response were investigated using the umu test employing Salmonella typhimurium NM 2009. Trp-P-2 induced induction of β-galactosidase was suppressed when pheophytin b was included in the test. In order to evaluate the mode of action of pheophytin b in the mixture of Trp-P-2, Trp-P-2 was analyzed using HPLC. Compared with a solution of Trp-P-2 alone, the absorbance peak of Trp-P-2 in the HPLC profile of the mixture of Trp-P-2 and pheophytin b was observed to be decreased. Also a new peak was not shown in the HPLC profile. To investigate the possible effect of pheophytin b on the S9 mix, the HPLC profile of a mixture containing Trp-P-2, S9 mix and pheophytin b was compared with a mixture containing only Trp-P-2 and S9 mix. The absorbance peak of the hydroxylated Trp-P-2 in the reaction mixture containing pheophytin b was observed to be smaller than the peak of the mixture without pheophytin b. From these results, it is suggested that pheophytin b limits the formation of hydroxylated Trp-P-2.
The suppressing effects of polysaccharide produced by Bacillus circulans on the SOS response of Salmonella typhimurium TA 1535/pSK1002 induced by AF-2, MNNG, 4NQO, Trp-P-2, IQ and MeIQx were compared with those of commercial polysaccharides to find a new physiological value as an additive to processed foodstuffs. The native polysaccharide produced by B. circulans strongly suppressed SOS response induced by IQ and MeIQx, and the suppression was increased with increasing polysaccharide concentration. Xanthan gum, which is an acidic polysaccharide produced by Xanthomonas campestris, and carboxymethyl cellulose (CMC) did not suppress SOS response induced by mutagens.
A simple method for the extraction of tea samples and conditions of HPLC analysis of pheophorbide-a (PB-a) and its related chlorophyll derivatives was developed. Tea samples were extracted with 85% acetone (v/v) with this solution injected directly into the HPLC column. The modified HPLC procedure developed included a gradient solvent system in which solvent A (95% ethanol (v/v) containing 0.005 M sodium chloride) and solvent B (80% ethanol (v/v) containing 0.005 M sodium chloride) were the mobile phase. PB-a, its derivatives and their C-10 epimers could be clearly separated and determined within 35 min. This analytical method could be routinely used to determine low levels of PB-a content (<10 mg/100g) and its related individual chlorophyll derivatives in green teas. Hence, it is applicable to the safety and quality control of green teas.
Ferulic acid esterase activity arose in the ceca of rats that were fed on acid hydrolysate of refined corn bran. The main component of this hydrolysate was soluble ferulic acid arabinoxylan ester. In order to determine the relationship between the ferulic acid esterase activity and intestinal bacteria, the ferulic acid esterase activities from the four kinds of typical bacteria in the intestine were measured. Ferulic acid arabinose ester (LMW) and ferulic acid arabinoxylan ester (HMW) were used as substrates. The enzyme from Lactobacillus acidophilus exhibited the highest activity when LMW was used as a substrate. However, when HMW was used, all enzymes from these bacteria exhibited trace activities. At the same time, Bifidobacterium bifidum showed high xylanase and arabinofuranosidase activities. It was suggested that the xylanase and the arabinofuranosidase from bacteria such as B. bifidum attacked HMW and degraded it to lower molecules at first. The ferulic acid esterase from bacteria such as L. acidophilus might then act to release ferulic acid in the cecum.
Degradation of soybean protein by Monascus-proteinase was investigated in order to reveal the role of the enzyme in the process of tofuyo ripening. The ratio of trichloroacetic acid-insoluble nitrogen of soybean protein to the total nitrogen in the reaction mixture decreased with increasing enzymatic reaction time. It was found that the digestion of soybean protein by this enzyme progressed as follows: initially, α'-, α-, and β-subunits in β-conglycinin, and then, the acidic subunit in glycinin were degraded. However, the basic subunit of glycinin still remained, and some polypeptide bands (around 10 kDa) were formed during the enzyme reaction. The degradation rate of soybean protein by this enzyme was affected by the ethyl alcohol concentration in the reaction mixtures.
Volatile compounds in the headspace gas of light and deep roasted sesame seed oil were analyzed by gas chromatography and gas chromatography-mass spectrometry. The present method resulted in good reproducibility (<6.6% as a relative standard deviation) in the determination of individual volatile components. About 64 compounds, including 30 heterocyclic compounds, 7 aliphatic aldehydes, 11 ketones, and 16 miscellaneous compounds, were identified. Peak area percentages of 2-methylpropanal, 2-butenal, 2- and 3-methylbutanal, 2-propanone, 2-butanone, 3-methyl-2-butanone, 2,3-butanedione, 2- and 3-methylfuran, and 2,5-dimethylfuran, all of which could not be detected by steam distillation and column adsorptive concentration (previous method), increased in deep roasted oil. Hexanal decreased from 6.13% to 2.55% in deep roasted oil. Compared with the previous method, pyridine, thiophenes, and sulfides could be detected only by the present method, but unsaturated aliphatic aldehydes could not.
It was reported that the acyl moieties of acylated anthocyanins with hydroxycinnamic acids were photo-isomerized from the trans- to the cis-isomer by light irradiation. We studied the effects of light irradiation on nasunin, p-coumaroylated anthocyanin from eggplant, and characterized the photo-isomerized anthocyanin by high performance liquid chromatography and fast atom bombardment mass spectroscopy. The photo-isomerization occurred under acidic conditions and was repressed with α-glucosylrutin that strongly absorbed ultraviolet light.
The tert-butylperoxyl radical (t-BuOO·) scavenging activities of ethanol extracts of 21 sweet potato cultivars with several flesh colors were examined using a tert-butyl hydroperoxide (t-BuOOH)/hemin/luminol system. Among them, sweet potato cultivars with purple flesh, which contained anthocyanins, had the highest t-BuOO· scavenging activities. Those cultivars with purple flesh also had the highest antioxidative activities against lipid peroxidation induced by auto-oxidation of linoleic acid. Most of the sweet potato cultivars with white, white-yellow, yellow and orange flesh had low t-BuOO· scavenging and antioxidative activities; however, some of them had higher activities. In all sweet potato cultivars tested, the t-BuOO· scavenging activities became higher with an increase in the total phenolic content.
The odor components of six different non-salted fermented soybean products in different parts of the world, Natto (Japan), Thua-nao (Thailand), Pepo (Myanmar), Libi ippa (East Bhutan), Kinema (West Bhutan) and Daddawa (Nigeria) were compared. Especially, the composition of pyrazines contributing to Natto odor was examined in these products. The odor concentrates were prepared by the method using porous polymers and were analyzed by gas chromatography and gas chromatography-mass spectrometry. Pyrazines were considered to contribute to the characteristic odor of the non-salted fermented soybean products because the compounds were detected commonly in all the products except two types of Libi ippa. The total concentration of the pyrazines was lower in Libi ippa, Kinema, and Daddawa and higher in Thua-nao and Pepo when compared with that of Natto. The composition of the pyrazines depended on the products.