Nikoo, MehdiRegenstein, Joe M.Noori, FarzanehGheshlaghi, Shima Piri...
9页
查看更多>>摘要：Autolysis (at fixed temperatures (40, 50, 60 degrees C) or gradually increasing temperatures (40-60 degrees C) with different times) was used to produce protein hydrolysates from rainbow trout processing by-products. Total proteolytic and trypsin activities with fixed temperatures was higher than gradually increasing temperatures, decreased with increasing autolysis time and temperature with fixed temperatures (P <= 0.05). TCA-soluble peptides decreased with increasing autolysis times from 1 to 3 h (P <= 0.05). Autolysis increased peroxide value and thiobarbituric acid-reactive substances in both lipids and hydrolysates, particularly with gradually increasing temperatures (P <= 0.05) and was associated with oxidation of polyunsaturated fatty acids. Sulfhydryl groups decreased, while protein carbonyls and solubility were increased with fixed temperatures at higher temperatures (50 and 60 degrees C) or with gradually increasing temperatures at longer autolysis time (P <= 0.05). Free radical scavenging activity and the metal chelating ability of hydrolysates were governed by autolysis times and temperatures. Results of size exclusion chromatography-high performance liquid chromatography indicated that autolysis for 1 h at lower temperature (40 degrees C) was sufficient to produce autolysates rich in small peptides from rainbow trout by-products. Autolytic hydrolysis might be useful for production of such protein hydrolysates.
查看更多>>摘要：Oleogels are being increasingly used as solid fat alternatives in food. Low-saturation chocolates (referring to chocolates with low content of saturated fat) were prepared by replacing 50 g/100 g cocoa butter with three oleogels (monoglyceric stearate, beta-sitosterol + lecithin, and ethyl cellulose oleogel), which were fabricated through different gelation mechanisms (crystalline particles, self-assembly fibers, and polymeric strands, respectively). The physical characteristics and microstructures of oleogel-based chocolates during isothermal (4 and 20 degrees C) and fluctuating (20 degrees C for 17 h and 29 degrees C for 7 h) storage conditions were evaluated for 60 d, including whiteness index, hardness, thermal behavior, and crystal polymorph. We found that oleogel-based chocolates exhibited bloom delaying property through assessing whiteness index and polarized light microscopy images, especially under fluctuating temperatures. Among three oleogel-based chocolates, beta-sitosterol + lecithin oleogel-based chocolate maintained the lowest whiteness index. Differential scanning calorimetry and Xray diffraction revealed that oleogel-based chocolates showed sustained thermal and polymorphic stability throughout the storage period. Crystal morphology of fat phase observed by polarized light microscopy confirmed the existence of stable beta crystals in oleogel-based chocolates. Collectively, oleogel-based chocolates not only lower the degree of saturation but also exhibit high physical and bloom stability during isothermal and fluctuating storage.
查看更多>>摘要：A high-performance nitrogen-doped chitosan-TiO2 nanocomposite to be used as a photocatalyst for patulin degradation in apple juice was successfully prepared by a simple precipitation method. The structure and properties were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR), and UV-Vis diffuse reflectance spectrum. According to XPS and UV-Vis analyses, nitrogen had been successfully doped into the TiO2 nanoparticle crystals and reduced the band gap energy of TiO2 nanoparticles. The synthesized nanocomposite was able to photocatalytically degrade the patulin in apple juice under ultraviolet irradiation. The patulin (500 mu g/kg) was completely degraded within 35 min, which exhibited significantly enhanced photocatalytic activities compared with TiO2 nanoparticles or chitosan-TiO2 nanocomposite. Moreover, the photocatalytic treatment significantly reduced the occurrence of juice browning, and had little effects on reducing sugar, pH, titratable acid and soluble solids of the apple juice. The nitrogen-doped chitosan-TiO2 nanocomposite would be an ideal photocatalyst for patulin degradation in apple juice due to its high photocatalytic activity and little effects on the quality of apple juice.
查看更多>>摘要：The disinfection efficacy of slightly acidic electrolyzed water (SAEW) has been recognized in food industry. However, the application of single SAEW limited its disinfection potential. The efficacy of the two-step disinfection with SAEW for the reduction of L. monocytogenes contamination on different food raw materials was evaluated compared to the one-step disinfection with SAEW in this study. Results demonstrated that SAEW could reduce both the natural aerobic bacterial count and inoculated L. monocytogenes population on endive and chicken immediately after processing and SAEW with approximately 60 mg/L of available chlorine concentration (ACC) had equal or higher antibacterial efficacy compared to NaClO solutions with approximately 150 mg/L of ACC. Moreover, SAEW treatments could control the growth of microbial populations of L. monocytogenes during storage and the efficacy on the microbial reduction was associated to the initial populations. In addition, the SAEW-treated food raw materials were stored and disinfected again after storage and the results showed that the two-step disinfection method could decrease the survival populations of L. monocytogenes by 24.8%-99.6% compared to the one-step disinfection of SAEW. Therefore, considering storage habits, the two-step disinfection of SAEW may be a better choice in the disinfection of non-consumed-directly food raw materials.
查看更多>>摘要：Egg shell that accounts about 11% of egg weight is one of the industrial wastes that in this research has been used for soybean oil bleaching. The effects of using 1% and 2% of five different types of adsorbents; egg shell powder, egg shell ash, acid activated egg shell powder, acid activated egg shell ash and commercial bleaching earth have been investigated on the bleaching of neutralized soybean oil. The peroxide value, free fatty acid, chlorophyll, carotenoids, metals (copper and iron) and oil retention were determined. Egg shell structure was investigated. According to the results, the bulk of the egg shell consists of calcium and some other compounds such as magnesium, iron and manganese while silicate is the main composition of commercial bleaching earths. The results indicated that soybean oil bleaching with 2% egg shell powder reduced carotenoids and chlorophyll contents up to 82.56% and 46.33%, respectively. Also using of adsorbents based on egg shell reduced significantly (p < 0.05) the peroxide value, free fatty acid contents and oil retention as compared to commercial bleaching earth. It might be concluded that egg shell powder as an industrial waste can be employed as an adsorbent and regarded as a good alternative for bleaching of edible oils due to its high efficiency to remove undesirable components (pigments, iron, copper, oxidation products and free fatty acids) from neutralized oils and environmental protection against acid pollution.
Vishnuraj, M. R.Devatkal, SureshVaithiyanathan, S.Kumar, R. Uday...
8页
查看更多>>摘要：Use of edible by-products like chicken giblets in processed meat products without proper ingredient declaration amounts to food adulteration. DNA based methods are not able to detect this type of intra species adulteration. Hence, organ specific microRNAs are employed in this study to develop an assay using digital droplet PCR (ddPCR). Eight miRNA target sequences were tested using Locked Nucleic Acid (LNA) miRNA primer (Exiqon, Qiagen, USA) in a QX200 Automated digital droplet PCR (Bio-Rad, USA). Annealing temperature and primer input volume were optimized using 20 mu L ddPCR reaction. Specificity of miRNA primers were confirmed through melt curve analysis as well as for impact of gDNA contamination using SYBR Green based qPCR. In sensitivity evaluation, LODabs and LODrel were reported to be 2.5 copies/mu L and 0.94 copies/mu L. Separate cut-off values were established for each miRNA targets in raw as well as cooked samples. Validated assay detected gizzard using gga-mir-148a -3p, gga-mir-126 -5p and gga-mir-490 -5p, heart using gga-mir-218 -5p and gga-mir-499 -3p and liver using gga-mir-122 -5p in raw as well as cooked samples at 25 g/100 g substitution level. The miRNA-ddPCR methodology established in this study can be a valuable tool for accurate detection of tissue origin of meat products.
查看更多>>摘要：Raman, near-infrared and fluorescence spectroscopy were evaluated for determination of collagen content in ground meat. Two sample sets were used (i.e. ground beef and ground poultry by-products), and collagen concentrations (measured as hydroxyproline) varied in the ranges 0.1-3.3% in the beef samples and 0.4-1.5% in the poultry samples. Similar validation results for hydroxyproline were obtained for NIRS (R-2 = 0.82 and RMSECV = 0.11%) and Raman (R-2 = 0.81 and RMSECV = 0.11%) for the poultry samples. For the beef samples, NIRS obtained slightly less accurate results (R-2 = 0.89, RMSECV = 0.25%) compared to Raman (R-2 = 0.94, RMSECV = 0.19%), most likely due to less representative sampling. Fluorescence spectroscopy gave higher prediction errors (RMSECV = 0.50% and 0.13% for beef and poultry, respectively). This shows that Raman spectroscopy employing a scanning approach for representative sampling is a potential tool for on-line determination of collagen in meat.
查看更多>>摘要：The diversity and technological properties of Pediococcus pentosaceus strains, isolated from some traditional fermented foods in Nigeria, were studied with the aim of selecting suitable strains as a starter and/or adjunct cultures. Eighteen lactic acid bacteria isolates from ogi, gari and fufu were presumptively identified as Pediococcus species using the conventional methods, these isolates were screened for technological and safety properties such as exopolysaccharide production, acidifying activity, antimicrobial activity, and biogenic amine production. The LAB isolates were further differentiated by using internal transcribed spacer-restriction fragment length polymorphism (ITS-RFLP), randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) and pulsed-field gel electrophoresis (PFGE) molecular typing techniques. The Pediococcus sp. displayed antimicrobial activities against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecium. They all had high acidifying activities and were able to reduce the pH to lower than 5.20 after 24 h. Pediococcus pentosaceus OF31 showed interesting potential technological characteristics due to its antimicrobial activity and exopolysaccharide production. The combination of RAPD-PCR (using primers OPA20 and M13) and PFGE-SfiI genotypic fingerprinting technique allows successful intraspecific differentiation. The present study confirmed the presence of exopolysaccharide-producing strain of P. pentosaceus in indigenous fermented foods which could be used as autochthonous starter culture to impart more functional attributes to fermented foods.
NSTL
Elsevier