This study was performed to investigate the physicochemical properties of lutein microencapsulation (LM) and to assess its bioavailability (BA). LM was prepared with advanced spray and starch-catching drying technology. Its physicochemical properties (characterization, storage stability and dissolution) and BA were evaluated. The BA study of LM was performed using SD rats following a single oral administration of lutein equivalent to 100 mg, and were compared with commercial reference sample (RS). LM was nearly sphericity, its mean particle size was 214.7 nm. It can be free-flowing. Solubility of lutein was increased and it could be directly dissolved in water to form a homogeneity of solution. The storage stability of lutein was enhanced under accelerated and long-term storage conditions. More than 85% lutein could be released from LM after 15 min during the dissolution test. The relative BA of lutein was 139.1% in comparison to RS. The results would be helpful to conduct the application of LM in food industry.
The distribution coefficients, Kapp, of non-electrolytes of different molecular masses on a tapioca starch gel were measured at a temperature range of 25 – 60°C. The swelling pressure of the gel was estimated from the coefficients at each temperature, and was observed to increase from 1 to 3 MPa with a temperature increase from 25 to 50°C. The swelling pressure, however, decreased at 60°C. The decrease was ascribed to the gelatinization of tapioca starch, which was observed using differential scanning calorimetry. The temperature dependency of the swelling pressure suggested a significant effect of gelatinization on the distribution equilibrium of a solute on the starch gel. The experimentally observed Kapp values of electrolytes (0.5 to 0.8) were lower than the values calculated using the swelling pressure and specific molecular volumes of the electrolytes. This suggested the involvement of another factor, such as an electrostatic interaction, in the distribution of electrolytes on the gel.
Recently, loop-mediated isothermal amplification (LAMP) method has been rapidly developed and shown promise for direct detection of genetically modified organisms (GMOs). We developed a LAMP method for detecting GM soybean DP-356043-5. The optimum amplification was performed at 65°C within 60min, with a set of four specific primers that recognize six distinct sequences on the target gene. The result verdict was based on SYBR Green I and agarose gel electrophoresis. Different plant materials were utilized to ensure the specificity of developed LAMP assay, and the result indicated high specificity. The sensitivity of LAMP was detected at low concentration (1% – 0.005%), and the limit of detection (LOD) was 0.05%, corresponding to about 20 copies. The results revealed the LAMP assay developed can provide a reliable and efficient method to detect the GM soybean DP-356043-5, which was a rapid and high-throughput analysis.
The change in viscosity of expressible water associated with mass transfer during meat cooking was described using dynamic viscoelasticity measurement of meat juice containing 78.9 ± 5.71 mg/mL of protein. We observed a temperature-dependent decrease in the complex viscosity of meat juice up to 49.4°C; however, the viscosity increased drastically when the temperature exceeded 60°C. This trend was similar to that observed for temperature-dependent denaturation of dissolved water-soluble proteins in the meat, suggesting that the change in viscosity of meat juice is dependent on the denaturation of dissolved water-soluble proteins as well as the temperature. Therefore, a hypothetical new model equation, incorporating the denaturation of water-soluble proteins into Andrade's equation (in order to demonstrate the relationship between liquid temperature and viscosity), enabled the estimation of changes in the viscosity of expressible water in meat associated with mass transfer at an arbitrary temperature during heating.
Thermoanaerobic spore-forming bacteria such as Thermoanaerobacter, Moorella, Thermoanaerobacterium, and Caldanaerobius produce spores with extremely high heat resistance. They are known to spoil various sealed, sterile drinks; in particular, low-acid drinks distributed at high temperatures, such as canned coffee containing milk. These bacteria are difficult to culture and identify on the basis of traditional biochemical characteristics. We developed novel primers for single and multiplex PCR methods for simple identification of these bacteria at the genus level. Bacteria were correctly identified approximately 2 h after DNA extraction among 86 strains of 35 species of Gram-positive and -negative bacteria including various spore-forming bacilli. Furthermore, new Loop-Mediated Isothermal Amplification (LAMP) primers were designed to develop a specific detection method for Thermoanaerobacter mathranii and Thermoanaerobacter thermocopriae, highly problematic microbes in the food industry due to their extremely high resistance to heat and various antibacterial agents. Our LAMP method using the novel primers was able to easily detect these microbes. Our present methods effectively improve upon the complicated procedures employed in the quality control of raw materials and products in the food industry.
Sweet potato a nutritious and abundantly available food crop in many developing countries has been explored for baking to increase its use in food processing. Though it often results in lower quality bread it can be improved with enzyme treatments. Thus, this study evaluated the effect of purple sweet potato powder (PSPP) supplementation, and α-amylase (AM) and hemicellulase (HC) treatments on the texture and retrogradation during storage, and structure of bread. Results showed that PSPP supplementation gave rise to bread with higher firming rate related with greater starch-gluten interaction. On the other hand, AM and HC treatment resulted in lower firming rate, amylose content, enthalpy of retrogradation, rupture properties, and moisture loss during storage of PSPP supplemented bread. These improvements in texture properties and structure indicate more acceptable bread that may lead in increased utilization of purple sweet potato.
The objective of this research was to develop a method using the fluorescence fingerprint (FF) to measure cheese maturation. FFs of sixteen cheese samples with maturation periods of 7 to 329 days were measured with 8 replicates for each sample, along with reference values of proteolysis index (ratio of soluble to total nitrogen) and total free amino acids. A partial least-squares (PLS) model to predict the maturation time, proteolysis index and free amino acids from the FF data was constructed. The coefficient of determination for cross-validation (R2CV) was 0.93, 0.79, and 0.90 for the three indices, respectively. From the loadings of the PLS model, it was found that emission spectra at 345 nm excitation, attributable to oxidized lipids and Maillard reaction products, increased in intensity with prolonged maturation time.
Several polyphenolic compounds which were derived from the fermented soybean had been identified and investigated for their potential effects on some diseases. However, such a biotransformation phenomenon is seldom discussed and has not been studied by using submerged culture with isoflavone, such as pure daidzein, as a substrate. In this study, the conditions for hydroxylation of pure daidzein into 8-hydroxydaidzein by Aspergillus oryzae were systemically investigated. Our results indicated that the optimal culture conditions for the hydroxylation were 200 rpm and pH 6. Moreover, the production was significantly increased 57.4% by an optimized concentration of 3 g/L MgSO4. On the other hand, 77.8% high biotransformation efficiency of 8-hydroxydaidzein could be obtained by providing pure daidzein; that can avoid many derived polyphenolic compounds were generated by isoflavone biotransformation. Our results suggest that the biotransformation of 8-hydroxydaidzein can be performed through a highly selected catalysis under specified conditions using certain microorganisms.
This study investigated the antioxidative and antiglycative abilities of flesh and peel extracts of Chinese purple yam. Among five fractions of purple yam extracts, the ethyl acetate (EA) fraction exerted the best antioxidant activity. Peel (P-EA) and flesh EA extracts (F-EA) exhibited excellent antiglycation ability by efficiently suppressing different stages of the glycation cascade, and the effect was mainly due to their antioxidant activities. The cytoprotective effect of F-EA and P-EA on methylglyoxal induced oxidative damage in HepG2 cells was also determined, and the underlying mechanism was the strengthened antioxidant defense system in HepG2 cells. Peel extract exerted better bioactivity than flesh extract, which indicated that purple yam peel, a kind of kitchen waste that is always overlooked, might serve as a promising therapeutic natural product for the prevention of diabetes or other advanced glycation end products-related diseases.
Ultra-high temperature (UHT) and retort processes are widely applied in the sterilization of liquid enteral formulae. This study investigated the effects of sterilization process on the physicochemical and nutritional properties of a liquid enteral formula. An ingredient mixture was sterilized by either UHT processing at 150°C for 5 s, or retort processing at 121°C for 10 min (retort A) or 121°C for 40 min (retort B). In vitro assays showed less protein modification in the UHT formula than in either retort formula. In vivo assays also demonstrated that net protein utilization was greatest with the UHT formula, and cecal nitrogen and ammonia concentrations in rats fed the UHT formula were lower than in rats fed either retort formula. These results indicate that the sterilization process affects the protein quality of the formula as well as the intestinal environment of rats fed the formula.
Although most Gram-positive bacteria are sensitive to epigallocatechin gallate (EGCg), some species of lactic acid bacteria (LAB) are highly tolerant. The mechanism of LAB tolerance to the antibacterial action of EGCg was investigated. LAB strains with three different cell wall composition types were used: Lactobacillus plantarum NBRC15891 (meso-DAP-type), Lactobacillus fermentum NBRC15885 (Orn-type), and Lactobacillus delbrueckii NBRC3073 (Lys-type). The minimum inhibitory concentration of EGCg for L. plantarum NBRC15891, L. fermentum NBRC15885, and L. delbrueckii NBRC3073 were >1000, >1000, and 500 µg/mL at pH 6.5, respectively. The cell surface hydrophobicity (CSH), and contents of extracellular polymeric substances (EPS) and teichoic acid of these strains suggested that strains with low CSH and producing greater amounts of EPS are highly resistant to EGCg at pH 6.5. After EGCg treatment, the membrane potential decreased in strains with high susceptibility to EGCg. Our findings suggested that LAB characterized by high EPS level and low CSH are resistant to EGCg at pH 6.5.
Yabumame, a legume family member, similar to hog-peanut, is an important traditional food for the Ainu people of Japan. However, its nutritional components and bioactivities are unknown. It has been suggested that low-density lipoprotein (LDL) oxidation by reactive oxygen species (ROS) may be a key factor in the onset of atherosclerosis. In this study, we evaluated the antioxidant activity of yabumame extract (YE) against LDL oxidation in vitro. Total polyphenol content in YE was 1.9%. YE showed 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity in solution. YE suppressed lipid peroxidation in LDL induced by free radicals or transition metal ions. YE also inhibited the oxidative modification of apolipoprotein B-100 in the oxidized LDL. The results suggest that YE can suppress LDL oxidation by ROS that leads to atherosclerosis.
Effects of ionic strength on chemical forces and functional properties of heat-induced myofibrillar protein gel were investigated. The decrease of total sulfhydryl groups suggested that more disulfide bonds formed with the increase of ionic strength. The increase of surface hydrophobicity and normalized intensity of 760 cm−1 band of Raman spectra indicated that higher ionic strength strengthened hydrophobic interactions. The decrease of normalized ratio of I850/I830 and absolute value of zeta potential indicated that higher ionic strength weakened hydrogen bonds and electrostatic interactions. The storage modulus (G′), hardness and water holding capacity (WHC) all increased significantly with the increase of ionic strength from 0.2 – 0.6 (p < 0.05). The enhancement of functional properties at higher ionic strength was achieved by strengthening attractive forces and weakening repulsive forces.
The aim of this study was to investigate the influence of milk on the aroma release and aroma perception of coffee. The amounts of in-mouth odorants exhaled through the nostrils during the consumption of black coffee and milk coffee were compared using the Retronasal Flavor Impression Screening System (R-FISS) by 3 trained panelists. As a result, it was found that the amounts of most in-mouth odorants including the potent odorants in brewed coffee did not significantly differ between the black coffee and milk coffee. However, the amounts of furfuryl methyl sulfide (FMS), difurylmethane, and furfuryl pyrrole exhaled through the nostrils during the consumption of milk coffee were significantly lower than those of the black coffee regardless of the panelist. It has been previously indicated that FMS could result from the methylation of 2-furfurylthiol (FFT), one of the most important potent odorants in brewed coffee. Based on these results, FFT and FMS were added to milk coffee so that the amount of FMS exhaled through the nostrils was about the same as that of black coffee, resulting in improved intensity of the coffee-like aroma quality for the milk coffee. The present results suggested that the significantly decreased intensity of the coffee-like aroma quality might result from decreased aroma release of a few odorants, including FFT, by the addition of milk to the coffee. Moreover, it was inferred that the difference in aroma release of FFT would have an especially significant impact on the perception of coffee-like aroma quality between the black coffee and milk coffee.
The present study evaluated the optimal parameters for Psidium guajava leaf extraction by ultrasound to obtain maximal anti-hyperglycemic activities in the extract. The response surface methodology was employed for empirical model building. The maximum inhibition of the two starch-digesting enzymes α-amylase and α-glucosidase was determined. The optimized extraction parameters of solvent-to-solid ratio, extraction time, and extraction temperature for obtaining the maximum inhibitory activity for 50 µg/mL extract were determined to be the following: 12.07 (v/w), 5.22 min, and 59.77°C for α-amylase (47.23% ± 0.76%) and 12 (v/w), 5.22 min, and 59.94°C for α-glucosidase (59.42% ± 0.65%), respectively. The F values for the lack-of-fit were not significant (p > 0.05) for both second-order models, indicating them to be appropriate for describing the response surface. In conclusion, our study presents the optimal conditions for ultrasound-assisted extraction of guava leaf as a potential substance for use in diabetes treatment.
The wild yeast Saccharomyces cerevisiae AK46 was isolated from cherry fruits and commercialized as baker's yeast. We isolated a 2-deoxyglucose (2-DOG)-resistant mutant of AK46 (MCD4) and evaluated its leavening ability in bread dough. Our findings show that the maltose utilization of MCD4 was significantly enhanced in the presence of glucose and α-glucosidase activity was increased by approx. 1.6-fold compared to that of AK46, indicating release from catabolite repression. In addition, baking performance results using the sponge dough and no-time dough methods showed that the CO2 production rate of MCD4 was increased by approx. 1.6-fold (sponge and dough method) and the specific volume of bread was increased by 6.3% and 7.8%, respectively. These results demonstrate that the 2-DOG resistance exhibited by MCD4 significantly improved the leavening ability in bread dough.
Aspergillus oryzae is known to have remarkable potential for the production of secreted enzymes. Submerged (Smf) and solid-state fermentation (SSF) are optimized with regard to temperature, pH, moisture, fermentation time, inoculum concentration, etc. Besides these parameters, the effect of light on growth and its role as a bioprocess variable in controlling enzyme production in A. oryzae is pivotal and hence the subject of study. A. oryzae was shown to be susceptible to light; growth was affected and the vegetative phase of the fungus was retarded. Biochemical alterations in biomass, growth diameter, chitin, and conidiation were also observed. The acid protease production by Smf and SSF showed improvement when incubated under darkness. Our study demonstrates for the first time that light must be considered as a bioprocess variable, as certain strains of A. oryzae are sensitive to light. Moreover, total darkness could be effectively employed in protease production on a pilot scale.