Effects of xylanase on the quality of frozen dough and steamed bread stored at a freezing temperature for 15, 30, and 45 d were investigated. Results showed that prolonging the frozen storage time can decrease the leavening power and yeast survival rate of frozen dough as well as the specific volume and anti-staling activity of frozen dough steamed bread. By contrast, these properties can be improved significantly through the addition of xylanase. The frozen dough supplemented with 80 mg/kg of xylanase had a low freezable water content (28.51 ± 0.37)%, which was 29.11% lower than that of the control (40.22 ± 0.43)%. The addition of xylanase can also significantly reduce the melting point and melting scope of ice crystals (P < 0.05), which can result in a homogeneous, small ice crystal structure in frozen dough and improve the quality of frozen dough steamed bread.
This study investigated the effects of pressure level, holding time, and storage period on the physicochemical properties of chilled abalone. Pressure level and storage period had a significant effect on the qualities of abalone, while the impact of holding time was negligible compared to those of pressure level and storage period. Pressurization at 400 – 500 MPa had the potential advantage to extend shelf-life of abalone to more than 15 days, while quality modifications were noticeably identified. Moderate pressurization (< 200 MPa) had no effect on the shelf-life of abalone. The optimal processing condition was 200 – 300 MPa at which the shelf-life of abalone could be extended to around 10 days with minimizing quality modification. Although, the mechanisms involved in shelf life extension and quality modification of pressurized abalone were not fully understood, the present study demonstrated the potential application of high pressure in the abalone industry.
Maintaining a suitable gas composition in a transportation container with controlled atmosphere is important. When O2 concentration is below the suitable value, gas exchange is activated to improve O2 concentration. Computational fluid dynamics was used to compute the effects of exhaust valve location, driving speed, and valve diameter on the gas exchange process. Gas exchange time can be reduced by relocating the exhaust valve to a lower area and by improving driving speed and valve diameter. Moreover, running the fan can shorten gas exchange time and enhance the distribution uniformity of the O2 volume fraction in a container. The influence of gas exchange on temperature in the container can be reduced by shortening processing time, but this reduction significantly affects the distribution uniformity of O2 volume fraction. A test was conducted to verify the accuracy of the numerical models. A good agreement was found between the simulation and test values of O2 volume fraction during gas exchange. Results reveal the rules and characteristics of gas exchange in fresh-keeping transportation containers with a controlled atmosphere.
A modified American Association of Cereal Chemists (AACC) parameter for white bread crumb, CFV20, was established using a 20-mm-diameter plunger, and represents an interchangeable parameter to compression force values (CFV) used in the AACC method. The relationship between CFV and storage days was expressed by a 2nd order polynomial equation. Using this equation, the storage days at maximum CFV was around 4 days at 5°C. In addition, mouthfeel firmness was evaluated by 20-year-old participants, and also showed a maximum score at around 4 storage days. Moreover, CFV20 reflected not only mouthfeel firmness but also tactile sensory score, resulting in a good parameter describing sensory white bread crumb firmness, and is interchangeable with CFV of the AACC method, evidenced by the high correlation between CFV20 and CFV of the AACC method.
The effect of calcium fertilization on the processing properties and storability of frozen French fries was investigated using three different varieties of processing-type potatoes, namely Toyoshiro (TS), Kitahime (KH) and Snowden. We attempted to understand the possible mechanisms contributing to quality differences in the French fries, by comparing tuber, starch and cell wall material properties. Calcium fertilization significantly increased the calcium contents of cell wall materials of all varieties, while a significant increase in chelating-agent soluble pectin content was observed in TS. The oil content of French fries was not significantly affected by calcium fertilization. On the other hand, two-way ANOVA indicated a significant effect of calcium fertilization on the hardness of the center and bud-end of French fries after 24 weeks of frozen storage. Results of this study suggest that calcium fertilization may be an effective method to improve the processing properties and storability of French fries.
In order to examine microbial decontamination by UV-C treatment of strawberries on a continuously moving conveyor, we developed a three-dimensional irradiation model based on a discrete ordinates (DO) method to evaluate UV-C dose distribution on strawberries. The sliding mesh method was employed to describe the motion of strawberries placed on a UV-C-transparent film tray on a conveyor through a UV-C treatment system. We also estimated total UV-C radiation dose distribution on the surface of strawberries for four different configurations. The models with four lamps installed in parallel to the direction of movement provided uniform dose distribution. The time required for three-log inactivation of Penicillium digitatum on the surface of strawberries was also calculated. For the optimal model (Model D), 131 s was required for three-log inactivation of P. digitatum. The proposed radiation model was shown to be a useful tool for the optimization of UV-C treatment for strawberry.
The microbial community in the fermentation process of Chinese homemade paocai (CHP), which was a traditional fermented vegetable food in China, was analyzed firstly by PCR-denaturing gradient gel electrophoresis (DGGE) and quantitative PCR (qPCR). In bacterial DGGE profile, a total of 15 bands were identified, which fell into two phyla including Firmicutes and Proteobacteria, and Weissella, Lactobacillus, Lactococcus, Bacillus, Citrobacter, Pantoea, Pseudomomas and unclassified Pseudomonadales were detected. Weissella, Lactobacillus and Lactococcus are dominant lactic acid bacteria (LAB) during the CHP fermentation. The number of Weissella, which was detected as the dominant bacteria during the whole fermentation, was quantitated and its quantity was shown to exist at 107 – 108 cells/mL during the fermentation. The results of fungal DGGE analysis demonstrated two genera, Pichia and Geotrichum, were detected and Pichia was the main yeast during the whole CHP fermentation process. There are microbial successions occurred in the CHP fermentation process.
In this study, a new method for producing cyclo(-Gly-Pro) using collagen as a raw material was examined. First, collagen was enzymatically hydrolysed and purified to obtain collagen tripeptide (CTP), rich in “Gly-X-Y” tripeptides. After heating this product under atmospheric pressure in an aqueous solution at 95°C for 24 h, purification was achieved by reverse-phase column chromatography. The isolated component was confirmed to be cyclo(-Gly-Pro) through structural analysis by MS and NMR spectroscopies. Purity was determined to be 93.6%, and the recovery rate from CTP was 22%, indicating that much Gly-Pro-Y in CTP contributed to cyclization. The cyclization rate from Gly-Pro-Hyp or Gly-Pro-Ala was much higher than that of Gly-Pro, suggesting that cyclo(-Gly-Pro) was efficiently generated from the Gly-Pro-Y sequence. In summary, this is a simple, practical manufacturing method for producing cyclo(-Gly-Pro) from collagen at low cost with high efficiency.
We evaluated the effect of both the change in velocity (Vc) and the peak acceleration (PAcc) on the bruise area (BA) of apple fruit by shock tests. The results demonstrated that the BA of apple fruit caused by shock changes depends on a combination of Vc and PAcc. We also drew damage boundary curves (DBCs) corresponding to the BAs that were determined from the combination of Vc and PAcc. Moreover, by using a multiple regression analysis, we inferred that an increase in the BA of apple fruit due to shock is caused by an increase in the PAcc, rather than the Vc; the relative contributions of the independent variables in the regression for Vc and PAcc were 0.48 and 0.71, respectively. This finding will contribute to the consideration of measures to counteract the occurrence of bruising of apple fruit during transport.
Noodles were prepared using wheat flour with 0 – 20% (w/w) added powdered gluten, and the transient changes in their moisture content during cooking were measured. Kinetic analysis of the water sorption process during cooking indicated that the process occurred in two distinct stages for all of the noodles. Water diffusion and consequent starch gelatinization predominantly controlled water sorption during the early stage, while relaxation of the gluten network structure was rate-limiting for the water sorption process during the latter stage. The moisture content, at which the rate-limiting factor for the water sorption process changed, was lower for the wheat noodles having a higher gluten content. Thus, it was suggested that the change in the gluten network structure induced by the addition of gluten to wheat flour affected the water sorption behavior of wheat noodles.
Volatile compounds of Camellia seed oils from 5 different varieties were characterized by headspace solid phase microextraction/ gas chromatography/mass spectrometry (HS-SPME/GC/MS). Four parameters of SPME were optimized and the best extraction conditions were: 50/30 µm DVB/CAR/PDMS fiber, 45°C and 45 min of SPME, and 4.00 g sample size. Forty-six volatiles were identified, including 16 aldehydes, 10 alcohols, 4 acids, 7 ketones, 3 terpenes and 6 esters. Further correlation analysis between aroma compounds and sensory attributes revealed pentanal, hexanal, (E)-2-hexenal, octanal, (E)-2-heptenal, nonanal, (E)-2-octenal, (E)-2-decenal, (E,E)-2,4-heptadienal, 2-hexanol, 2-heptanol, hexanol, octanol, acetic acid, pentanoic acid, 1-p-menthene, limonene, γ-terpinene, ethyl-2-methylbutanoate, 2-methylbutyl acetate, ethyl 2-methyl-2-butenoate, γ-butyrolactone, γ-hexalactone were the important characteristic aroma compounds of Camellia seed oils. Additionally, electronic nose (e-nose) was applied to analyze the aroma of Camellia seed oils. HS-SPME/GC/MS and e-nose techniques combined with multivariate analysis can be used to distinguish between different Camellia seed oils.
Fucoidan from sea cucumber is reported to exhibit anti-hyperglycaemic effect, but its influence on pancreatic islets is lacking. The effects of fucoidan from Cucumaria frondosa (Cf-FUC) on inhibiting pancreatic islets apoptosis in high-fat high-sucrose diet (HFSD)-induced insulin resistant mice were investigated in this study. The results showed that Cf-FUC significantly prevented HFSD-injured pancreatic islets, decreased blood glucose, insulin and TNF-α levels, and increased adiponectin level. Cf-FUC significantly reduced Bid, Bax, cytochrome c, caspase 9, and caspase 3 mRNA expression levels, and increased Bcl-2 and Bcl-xL mRNA expression levels. Cf-FUC also caused significant down-regulation of t-Bid, Bax, cytochrome c in cytoplasm, caspase 9, and cleaved-caspase 3 proteins, and up-regulation of Bcl-2 and Bcl-xL proteins. Furthermore, Cf-FUC enhanced the effects of RSG. This study demonstrates that Cf-FUC inhibits pancreatic islets apoptosis via inhibiting mitochondrial pathway, which may provide a dietary intervention hyperglycaemia-induced pancreatic islets apoptosis.
With the predominance of producing γ-aminobutyric acid (GABA) in milk fermentation as basis, the objective of this study was to investigate the production of high-vitality starter cultures by Lactobacillus plantarum NDC 75017. The strain, isolated from traditional yogurt in Inner Mongolia of China, can produce γ-aminobutyric acid-enriched fermented milk and possesses beneficial properties. In this study, the strain was grown in optimized mMRS media in 3.7 L fully instrumented fermenter to produce biomass. Cells grown in the stationary phase were harvested and freeze dried. The viable cell count was up to 2.22 × 1011 CFU g−1 of freeze-dried product upon the addition of 8% w/v trehalose, 4% w/v maltodextrin, 4% w/v L-glutamate sodium salt, and 10% w/v skim milk as cryoprotectants. These freeze dried cells were stored at temperatures of 25°C and 4°C and periodically checked for viability and preparation of fermented milk, which showed a higher cell viability and stability after stored at 4µC in 210 days. Based on our result, the high-viability starter cultures could be easily and economically produced.
Molecular nutrition study is essential for assessing food quality. Pyropia haitanensis is nutritious and delicious health food in southern China. Consumers prefer the first harvested P. haitanensis for its tender taste. To understand the comprehensive alteration in the nutrition of P. haitanensis with different harvest time, we characterized the metabolomic variations induced by harvest time using NMR spectroscopy coupled with multivariate data analysis. We found that harvest time was an important factor influencing the nutrient composition of P. haitanensis. The levels of glutamine, alanine, aspartate, taurine, and isofloridoside contained in seaweeds were significantly increased over the harvest time. These findings enhanced our understanding of the nutritional features of P. haitanensis harvested at different times and provided useful information on the quality assessment of P. haitanensis.
Bamboo hemicellulose hydrolysate (BHH) was extracted from bamboo by high temperature and enzymatic treatment. The ratio of total sugars in BHH was 75.7% on a dry matter basis (sugar components: 46.4% glucose, 12.7% arabinose, 40.9% xylose). These were mainly comprised of low molecular weight oligosaccharides containing ferulic acid. BHH exhibited strong anti-oxidative activities. In high fat (HF) diet-fed mice, 5% BHH supplementation significantly ameliorated increases in plasma cholesterol levels compared to the control mice fed HF diet alone. Also, while the fecal pH of control mice increased, that of test mice (5% BHH supplementation) did not increase to similar levels. Greater amounts of propionic acid were detected in the feces of HF diet-fed mice fed HF supplemented with BHH than one fed HF diet alone.
The effect of milk fat (MF) and milk solids–nonfat (MSNF) on the release of retronasal-aroma (RA) compounds from coffee with milk was investigated by correlating with the lipophilicity (log kw) of the compounds. RA compounds of a coffee flavor-added (FA) sample with MF (0 – 3%) and/or MSNF (0 – 8%) were collected by exposing a solid-phase microextraction fiber to RA simulator effluent gas and analyzed by gas chromatography-mass spectrometry (GC-MS). GC-MS analysis of volatiles released from the FA sample revealed that the relative release ratios of compounds with log kw values >2 decreased significantly as the MF and/or MSNF content increased. Changes in relative release ratios with different MSNF contents were smaller than those with different MF contents, indicating that MF is the predominant factor affecting RA compound release. In FA samples with 0.5 – 3% MF, relationships between the relative release ratios and log kw values could be approximated by sigmoid functions, and exponential regression models for the relative release ratios at different MF contents were obtained for compounds with log kw >2. The resulting model for FA samples is applicable to coffee-added samples for the prediction of relative release ratios.
A Tartary buckwheat variety, ‘Manten-Kirari’, which is rich in rutin but lacks bitterness because of trace rutinosidase activity, was recently developed. Rutin content was 1,269 and 1,421 mg/100 g DW in dried noodles and cookies made with 50% ‘Manten-Kirari’ flour, respectively. The residual ratio of rutin during preparation of dried noodles and cookies was 99.3% and 80.6%, respectively. Hydrophilic antioxidant capacity (H-ORAC) was 149.8 µmol TE/g DW and 209.2 µmol TE/g DW in dried noodles and cookies, respectively. The contribution ratio of rutin to H-ORAC was 96.2% and 69.8% in dried noodles and cookies, respectively. These results indicated that the antioxidative activities of dried noodles and cookies made with ‘Manten-Kirari’ flour were mainly due to the hydrophilic antioxidant rutin. Tartary buckwheat ‘Manten-Kirari’ is a potentially excellent source of antioxidative food, and is characterized by a high rutin content and minimal bitterness.
Fruits are a major dietary source of phytochemicals with health benefits for humans. In particular, apples are an important source of dietary phytochemicals including procyanidins. Thus, in the present study, we investigated procyanidin concentrations in apples using normal-phase high-performance liquid chromatography with fluorescence detection and hydrophilic oxygen radical absorbance capacit. (H-ORAC) values. Apple procyanidin concentrations were significantly correlated with H-ORAC values (r = 0.8284, P < 0.0001) in 30 varieties of apple cultivars (dessert, processing and crab apples). These data suggest that the anti-oxidative activity of apples is mainly due to procyanidins.
Unripe apples contain large quantities of starch and represent an unused organic resource. Starch hydrolysis in unripe apples may provide an effective method to utilize this resource as a food material. Aspergillus oryzae can be grown using unripe apples. However, the activity level of α-amylase produced by A. oryzae grown in dried unripe apple pulp remains unconfirmed. Therefore, we here examined various culture conditions that might increase this α-amylase activity. Our results suggested that for culturing A. oryzae in dried unripe apple pulp using the shaking culture method, the addition of NaNO3 and MgSO4·7H2O as nitrogen and magnesium and/or sulfur sources, respectively, was essential. Thus, α-amylase production by A. oryzae required high oxygen levels and additional nitrogen and magnesium and/or sulfur sources, both of which occur in low quantities in dried unripe apple pulp.