The potential of spent mushroom substrate after cultivation of Pleurotus eryngii as a biomass resource for bioethanol production was investigated. Materials were pretreated by ball milling for 1 h, and enzymatic hydrolysis was then carried out. Glucose, xylose, arabinose and galactose were detected in enzymatic hydrolysates, and a > 59.0% yield of total sugars was obtained, even at a substrate concentration of 30% (w/v). Enzymatic hydrolysates were fermented using Pichia stipitis. When enzymatic hydrolysates obtained from a 20% (w/v) substrate concentration were fermented, the maximum ethanol concentration was 17.7 g l -1 and ethanol yield was 67.0%. These results indicate that corncob-based spent mushroom substrate can be used as a raw material for bioethanol production.
The degradation processes of N-acetyl-D-glucosamine (GlcNAc) and D-glucosamine in subcritical water were measured using a continuous tubular reactor at 170 to 210°C, and at 190 to 230°C, respectively. The degradation processes obeyed first-order kinetics in the tested temperature ranges. The temperature dependences of the degradation rate constants could be expressed by the Arrhenius equation, and the activation energies and the pre-exponential factors for GlcNAc and glucosamine were estimated to be 126 kJ/mol and 2.83 × 1012 s-1, and 130 kJ/mol and 2.11 × 1012 s-1, respectively. The pH values of the reaction mixtures, which were measured at room temperature, decreased for both substrates during degradation. The main degradation product of glucosamine was determined to be 5-(hydroxymethyl)-furfural. The degradation product of glucosamine possessed weak radical-scavenging ability, while that of GlcNAc did not.
In this paper, thin layer drying of peeled longan is presented. Thin layer drying of peeled longan was conducted under controlled conditions of temperature and relative humidity. Drying air temperature has great influence on the drying rates of peeled longan and drying time decreases with the increase in drying air temperature. Eight different thin layer drying models were fitted to the experimental data of peeled longan. The drying parameters of peeled longan were function of air temperature and relative humidity. Page model was found to be the best and Two-term model was found to be next to the best. The agreement between the predicted and experimental values for Page model is excellent. The predictions of Page model, Two-term model and modified Henderson and Pabis model were very close. Either one of these three can be used to provide design data and for simulation and optimization of the dryer for efficient operation. The colour of the peeled dried longan is golden brown for the temperature levels of 50, 60 and 70°C and there is no difference in colour for dried longan for drying at 50 to 70°C.
The influence of a combination of ultraviolet (UV) irradiation with infrared radiation heating (IRH) and conductive heating (CH) on the inactivation of bacterial spores (Bacillus subtilis) was investigated at 20, 30, 40, and 50°C on the surface of agar plates. The survival curves of B. subtilis spores were convex downward. Generally, the inactivation efficiency of UV irradiation with IRH was greater than that with CH for B. subtilis spores. A 4.1 log reduction of B. subtilis spores was obtained by 60 sec of UV irradiation with IRH at 50°C. The highest decimal reduction time was obtained at around 30°C of IRH. These variations in the inactivation characteristics of UV irradiation might be caused by differences in the UV and IR absorption characteristics of spores exposed at different temperatures.
Inactivation effects of infrared radiation (IR) heating (1.87 μW/cm2/nm) and ultraviolet (UV) irradiation (0.455 mW/cm2) on two mold spores (Penicillium, Cladosporium) were investigated before and after germination on potato dextrose agar. Penicillium was more resistant to IR heating than Cladosporium both before and after germination. Over 90% of Cladosporium was inactivated by 120 sec of IR heating after germination for up to 36 hours. The inactivation ratio of Cladosporium was temporarily increased for periods of 6 to 12 hours after 60 sec of IR heating and decreased to < 10 % by 30 sec of UV irradiation at 18 hours. In contrast, about 75% of Penicillium was inactivated by 30 sec of UV irradiation at 36 hours. These findings indicate that the ability of IR heating and UV irradiation to inactivate germinated molds is affected by mold type and growth stage.
Brown linseed (Linum ustatissimum) is pressed to produce oil, and the remaining linseed meal is rich in protein and soluble dietary fiber. To utilize the derivatives of linseed meal as food ingredients or additives, linseed meal was fractionated by controlling pH on a pilot-plant scale. Chemical composition, functional properties and health-related bioactivities, such as angiotensin-converting enzyme (ACE) inhibition and antioxidant activities, of the fractions were then analyzed. The alkaline soluble protein had the highest content of secoisolariciresinol diglucoside (SDG) and showed good emulsification activity, comparable to that of whole egg. The acid-soluble fraction showed the highest viscosity. ACE inhibition, antioxidant activities, and bile acid binding activity were observed in the soluble dietary fiber fraction. There was no correlation between SDG content and bioactivities. These findings indicate that the acid-soluble fraction is useful as a food ingredient to increase viscosity, while the soluble dietary fiber fraction has health-related features.
The amount and fatty acid composition of lysophosphatidylcholine (LPC) in the gelatinization, pasting and gelation of wheat starch were measured under a specific temperature program of a Rapid Visco Analyzer. The amount of LPC extracted from native starch in boiling water (HOT-LPC) with water-saturated n-butanol (WSB) was higher than that extracted at room temperature (RT-LPC). However, in the starch suspension at the beginning of gelatinization and in starch paste with increasing viscosity, the amounts of RT-LPC were higher than HOT-LPC. However, in starch paste with decreasing viscosity and starch gel, the amount of HOT-LPC was again higher than RT-LPC and similar to that of the native starch. The proportion of palmitic acid (PA) in HOT-LPC of starch paste with increasing viscosity was over 50%. However, in HOT-LPC of native starch and starch gel, the proportion of PA was lower than that of linoleic acid. These results indicated that the distribution of starch LPC changed during gelatinization, pasting and gelation of wheat starch.
The applicability of headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography and mass spectrometry (GC/MS) for determination of volatile flavor components (VFCs) of 4 kinds of Chinese fermented black soybeans (CFBS) collected from 4 different regions of China (Chongqing Yongchuan, Guangdong Yangjiang, Hunan Liuyang and Jiangxi Hukow, respectively). Principal component analysis (PCA) was used to visually compare their VFCs. Sixty-five VFCs were identified from 4 kinds of CFBS. These VFCs were divided into 11 categories including 13 acids, 7 alkenes, 7 alcohols, 6 aldehydes, 10 esters, 1 ether, 3 ketones, 5 phenols, 9 pyrazines,1 sulfide and 3 miscellaneous. In PCA comparison, Chongqing Yongchuan had the highest amount of phenethyl alcohol responsible for intense sauce-like aroma. Guangdong Yangjiang characterized by ginger aroma, was rich in zingiberene. Hunan Liuyang had stronger fatty aroma because of its higher ester content, while Jiangxi Hukow was richer in nutty aroma due to its plentiful pyrazines.
We measured anthocyanin levels in fresh açai (Euterpe oleracea Mart.), a native Amazonian palm fruit; cyanidin-3-O-glucoside (C3G) and cyanidin-3-O-rutinoside (C3R) in mesocarp/epicarp portion were 5.49 and 13.0 mg/g extracts, respectively, and these amounts were remarkably higher than that in endocarp. Hydrophilic ORAC assay suggested that açai mesocarp/epicarp extracts had potent antioxidant activity compared to blueberry extract. Following, absorption and excretion of açai anthocyanins were evaluated. After oral administration of açai extracts (400 mg/kg body weight) to rats, C3G and C3R appeared as intact forms in the plasma as maximum amounts of 101.0 ± 55.6 nmol/L at 60 min and 537.0 ± 99.1 nmol/L at 120 min after administration, respectively. Most of these anthocyanins were excreted in urine by 2 h post-administration time. In conclusion, fresh açai contained hydrophilic antioxidants including C3G and C3R, and therefore has strong antioxidant potency especially in the mesocarp/epicarp portion. Upon consumption, açai anthocyanins appeared as intact forms in plasma.
Proanthocyanidin (PA), total phenol (TP) and alcohol concentrations, as well as the spectrophotometric parameters, of 165 commercial Japanese red wines made from Muscat Bailey A (hybrid: Bailey × Muscat Hamburg, MBA), Cabernet Sauvignon (Vitis vinifera, CS), Merlot (V. vinifera, MER), and Zweigeltrebe (V. vinifera, ZR) were measured. MBA wines had extremely low PA concentrations (65 mg catechin equivalent (CAE) /L), as compared to CS (312 mg CAE/L), MER (356 mg CAE/L) and ZR wines (412 mg CAE/L). PA concentration was positively correlated with TP concentration and color intensity. A negative correlation was also observed between PA concentration and color hue value. Although alcohol is known to be important for the extraction of PAs into wine, its concentration showed no correlation with PA concentration.
A method to determine cysteine content in food materials using 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxidiazole (ABD-F) was compared to a method using N-acridinyl maleimide (NAM). Cysteine in samples was derivatized with two fluorogenic reagents and analyzed using HPLC. The cysteine derivative with ABD-F gave a single peak while the cysteine derivative with NAM produced three peaks in standard. The cysteine content in model samples determined with ABD-F was nearly identical to the content determined with NAM. However, when the cysteine content of six types of food materials was measured, four samples were identical in each method, but two samples produced different results because the separation of cysteine derivatives with NAM was influenced by other compounds in the food samples. Since the ABD-F method gave the better separation, it can be useful for the determination of cysteine content in food materials.
Green beans and roasted beans of coffee with Rio flavor were analyzed by gas chromatography-olfactometry to clarify the causal substances of Rio flavor in Brazilian coffee. In addition to 2,4,6-trichloroanisole (TCA) and 2,4,6-trichlorophenol (TCP), which are known as the main causal substances of Rio flavor, a new iodine-like flavor-causing compound, 2,6-dichlorophenol (DCP), was detected. The detected amounts of 2,6-DCP and 2,4,6-TCA were less than 0.1 and 0.1 ppb in Rio flavor-free coffee beans, 0.8 and 1.2 ppb in weak Rio flavored beans, and 3.0 and 2.6 ppb in strong Rio flavored beans, respectively. Musty and chlorine flavors were sensed more strongly in model coffee containing both 2,4,6-TCA and 2,6-DCP than in the coffee containing them individually. In the present study, 2,6-DCP was identified as a new causal substance of Rio flavor, and it was found that the presence of 2,4,6-TCA intensifies Rio flavor, as a synergy effect.
In this study, we investigated preventive effects of black tea on obesity and hyperglycemia in C57BL/6 mice fed a high-fat diet for 14 weeks. During the feeding period, mice were given the following black teas: BT1 containing 3,000 mg/L total catechins and 864 mg/L caffeine; and BT2 containing 1,437 mg/L total catechins and 594 mg/L caffeine. Both BT1 and BT2 suppressed high-fat diet-caused body weight gain, deposition of white adipose tissue, and increases in plasma lipids and glucose. Moreover, both BT1 and BT2 counteracted the high-fat diet-caused decrease in the expression of insulin receptor (IR)-β and glucose transporter 4 (GLUT4), markers for insulin resistance. Of these effects, BT2 were stronger than that of BT1. In conclusion, black tea prevents hyperglycemia and insulin resistance through maintenance of IR-β and GLUT4 expression in high-fat diet-fed mice, with an appropriate concentration of tea producing maximal effectiveness.
We present the use of near-infrared (NIR) spectroscopy with particle size compensation to analyze the apparent amylose content in rice flour. NIR spectra (1100 − 2500 nm) of rice flour samples with different particle sizes were acquired in the reflectance mode. Initially, the effect of rice flour particle size on the determination of amylose content using NIR data was examined. The bias introduced by particle size was discussed. Subsequently, in order to obtain an authentic and accurate apparent amylose content analysis from the NIR data, a calibration model that compensates for particle size was investigated. As a result, a possible automatic method that removes the influence of particle size on NIR data used for determining the apparent amylose content of rice flour was developed with relatively good precision, with standard error of prediction (SEP) of < 1.53% and bias of 0.5%.
Twenty-two strains of Saccharomyces cerevisiae isolated from tape-mash for the production of brem, a traditional rice wine from Bali, Indonesia, were divided into three groups (I, II, and III) based on the sequences of the rDNA spacer region and SUC2 gene. DNA analyses suggested that the seventeen strains in groups II and III were taxonomically closer to baking strains than the five strains in group I. These differences were reflected in their leavening ability in dough with and without addition of 5% sucrose, and their α-glucosidase activity, although most of the strains did not leaven dough with addition of 30% sucrose. Strain S-10 in group II showed a high rate of CO2 production from sponge dough without addition of sugar and consumed fermentable sugar within 2.5 h. When baking tests were conducted, strain S-10 and commercial baking strain HP 216 yielded comparable products by the straight-dough and sponge-dough methods.
The antimicrobial activity of edible films from whey proteins, alginate, zein and chitosan incorporated with polylysine (PL) and PL-ethylenediaminetetraacetic acid (Na2EDTA) combination have been tested on different bacteria including Escherichia coli, Listeria innocua, Salmonella Typhimurium and Stapylococcus aureus. The PL-containing films of whey proteins, alginate and chitosan were effective on L. innocua, but had limited effect on E. coli. On the other hand, the PL-containing zein films showed good antimicrobial activity on both E. coli and L. innocua as well as on S. aureus. PL-Na2EDTA combination also gave zein films effective on S. Typhimurium. The incorporation of PL alone or PL-Na2EDTA combination did not cause any significant change in mechanical properties of zein films. Zein has a good potential to develop novel antimicrobial packaging materials incorporated with PL.
The non-linear rheological properties of commercial mayonnaise were studied. The stress growth behavior under constant shear flow was observed using a strain control-type rheometer. As the stress-strain curves of commercial mayonnaise showed non-linear behavior, the curves were analyzed with a polynomial model that is a power series of strain. Two types of commercial mayonnaise were investigated in this study; traditional and low-fat mayonnaise. The second order coefficient of the polynomial model revealed that the structure fracture behavior of these types of mayonnaise was very different. Because the fracture behavior of semisolid foodstuffs is considered to be an important mechanical property, the present approach may be useful for quantitative estimation of the texture of such foods.
The preservative effects of different types of polyhydroxyl compounds on the stability of biocatalysts, β-amylase, pyruvate kinase and heat shock proteins, under dehydration stress were investigated. Polyhydroxyl compounds used in the present study were trehalose, sucrose, raffinose, maltose, lactose, glucose, glycerol, and dimethyl sulfoxide. The enzymatic activity of β-amylase was lost following both freeze-drying and air-drying; that of pyruvate kinase was lost only after air-drying. Non-reducing sugars, including trehalose, sucrose, and raffinose had marked preservative effects on the stability of these two biocatalysts. In contrast, glycerol caused the deterioration of their enzymatic activities. To our surprise, however, glycerol effectively retarded the inactivation of heat shock proteins, GroEL and Hsc73, caused by short-term dehydration. These findings are of considerable significance for understanding the interplay between heat shock proteins and the stress-induced accumulation of glycerol in anhydrobiotic organisms. Moreover, the utilization of non-reducing sugars as well as glycerol for storage of food materials and certain specific biocatalysts has been elucidated.