Enhanced biomass delignification and enzymatic saccharification of canola straw by steam-explosion pretreatment.

BACKGROUND: In recent decades, bioconversion of lignocellulosic biomass to biofuel (ethanol and biodiesel) has been extensively investigated. The three main chemical constituents of biomass are cellulose, hemicellulose and lignin. Cellulose and hemicellulose are polysaccharides of primarily fermentable sugars, glucose and xylose respectively. Hemicellulose also includes small fermentable fractions of arabinose, galactose and mannose. The main issue in converting lignocellulosic biomass to fuel ethanol is the accessibility of the polysaccharides for enzymatic breakdown into monosaccharides. This study focused on the use of steam explosion as the pretreatment method for canola straw as lignocellulosic biomass. RESULTS: Result showed that steam explosion treatment of biomass increased cellulose accessibility and it hydrolysis by enzyme hydrolysis. Following 72 h of enzyme hydrolysis, a maximum cellulose conversion to glucose yield of 29.40% was obtained for the steam-exploded sample while the control showed 11.60% glucose yields. Steam explosion pretreatment increased glucose production and glucose yield by 200% and 153.22%, respectively, compared to the control sample. The crystalline index increased from 57.48% in untreated canola straw to 64.72% in steam-exploded samples. CONCLUSION: Steam explosion pretreatment of biomass increased cellulose accessibility, and enzymatic hydrolysis increased glucose production and glucose yield of canola straw.

The effect of maltodextrin edible coating containing pyracantha extract and potassium nano-carbonate on secondary metabolites, antioxidant capacity and microbiological properties of grape during cold storage.

This study aimed to investigate the postharvest application of edible coating of maltodextrin containing potassium nanoparticles (KNPs; 0-2%) and pyracantha extract (PE; 0-1.5 %) on the maintenance of phenolic compounds, antioxidant capacity and microbial properties of 'Rishbaba' grape during 60 days at -1 °C using response surface methodology and central composite design. The results showed that the applied coating on Rishbaba grape maintained total phenol, total flavonoids, total anthocyanin, stilbenes (resveratrol and viniferin) and catechin. That also caused higher antioxidant capacity and lower mold and yeast growth in grape during the storage time. Finally, the best cold storage conditions of 'Rishbaba' grape were determined by using the edible maltodextrin coating containing 2 % KNPs and 1.5 % of PE for 34 days with a desirability of 0.728 in terms of investigated Characteristics. The optimized sample has the amount of total phenol (5.79 mg/g), total flavonoid (8.95 mg/g), total anthocyanin (6.48 mg/g) and the greatest ability to inhibit DPPH free radical (42.56 %) and the lowest growth rate of mold and yeast (21 Cfu/g).

Determination of phenolic compounds and their antioxidant activity of Iranian Allium sativum controversum extracts and their antimicrobial properties in fresh sausages.

In this study, Iranian Allium sativum controversum extracts, as a valuable source of bioactive compounds such as antioxidants, extracted by solvents were analyzed. Based on the analysis of total phenolic content (TPC) and total flavonoid content (TFC) and radical scavenging activity (1,1-diphenyl-2-picrylhydrazyl (DPPH)) of each extract, ethanol extracts were finally added to the sausage formulation at 0.5 and 1.5%w/v. Treatments were kept at refrigerated temperature (4-5°C) for 1, 15, and 30 days, and DPPH and microbial assays were performed on the treatments and the control samples. Experimental data were performed in a completely randomized design with the factorial arrangement. Hydroalcoholic extract had the highest total phenols and the aqueous extract of Allium sativum controversum showed the highest radical scavenging activity (11.85 ± 0.81 mg/g). No colony counts were observed on the first day of the coliform count. On 15 to 30 days, the control sample showed the highest count and the treatment containing Allium sativum controversum extract (1.5%) had the lowest coliform count. During the first month, the control sample had the highest count of Staphylococcus aureus. Regarding mold and yeast, a treatment containing Allium sativum controversum extract (1.5%) and the control sample had the lowest and highest count, respectively. The results showed that using Allium sativum controversum extracts and increased radical scavenging activity reduced microbial growth during the storage period.

Chemical composition, antioxidant, and antimicrobial activities of P. roxburghii oleoresin essential oils extracted by steam distillation, superheated steam, and supercritical fluid CO2 extraction.

Pinus roxburghii is a rich source of high-quality oleoresin that is composed of resin acids and essential oil (EO). The present research work was planned to study and compare the yield, biological activities, and chemical profiling of P. roxburghii oleoresin EOs extracted through various green extraction methods. Steam distillation (SD), supercritical fluid extraction, and superheated SD (SHSD) at different temperatures (120, 140, and 160°C) were employed to extract EOs from P. roxburghii oleoresin. Antioxidant potential of EOs was determined by total antioxidant content/ferric-reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging activity (DPPH-FRSA), hydrogen peroxide scavenging assays, and percentage inhibition in linoleic acid. Antimicrobial activity of EOs was determined by resazurin microtiter-plate, disc diffusion, and micro-dilution broth susceptibility assays. Gas chromatography-mass spectrometry was used to determine the chemical composition of EOs. It was observed that extraction methods significantly affected the yield, biological activities, and chemical composition of EOs. The maximum yield (19.92%) was found in EO extracted by SHSD at 160°C. EO extracted by SHSD at 120°C showed the highest DPPH-FRSA (63.33% ± 0.47%), linoleic acid oxidation inhibition (96.55% ± 1.71%), hydrogen peroxide scavenging activity (59.42% ± 0.32%), and total antioxidant contents/FRAP (134.49% ± 1.34 mg/L of gallic acid equivalent). The antimicrobial activity results showed that superheated steam-extracted EO of 120°C revealed the highest antifungal and antibacterial activity. It is concluded that SHSD is an alternative and effective technique for the extraction of oleoresins EO that improves the EO yield and biological activities. Further research on optimization and experimental parameters for the extraction of P. roxburghii oleoresin EO by SHSD is required.

The assessment of microencapsulated Lactobacillus plantarum survivability in rose petal jam and the changes in physicochemical, textural and sensorial characteristics of the product during storage.

The present study aimed to develop a probiotic rose petal jam containing microencapsulated L. plantarum. The attributes of L. plantarum microcapsules and bacteria viability in simulated gastrointestinal conditions and jam were assessed. In addition, L. plantarum effects on physicochemical, textural and sensorial properties of jam were studied. The microencapsulation yield, diameter, and zeta potential value of the microcapsules ranged from 90.23 to 92.75%, 14.80-35.02 µm, and - 16.83 to - 14.71 mV, respectively. The microencapsulation process significantly increases the survival of L. plantarum in simulated gastrointestinal tract and jam. In jam samples containing L. plantarum microencapsulated with 2% sodium alginate and 3.5% or 5% Arabic gum and stored for 90 days, the bacterial count was higher than the acceptable level (106 CFU/g). While there was no significant difference (P > 0.05) between physicochemical characteristics of non-probiotic and probiotic jams, taste and overall acceptance scores of microencapsulated probiotic jams were higher. The microencapsulation of L. plantarum in sodium alginate (2%) and Arabic gum (5%) and its inoculation into rose petal jam could yield a new probiotic product with increased health benefits.

Effect of methyl cellulose coating on physicochemical properties, porosity, and surface diameter of pistachio hull.

Pistachio is a nut with high consumption that can be affected by aflatoxin contamination. Regarding influence of this fungus on global trade, broad studies in this area seem to be necessary. In this research, pistachio nuts were coated with methyl cellulose at different concentrations of 0.1%, 0.5%, 1%, and 2% by immersion method. Samples were stored in an incubator (25°C) for 4 months. Imaging was performed by electron microscope using SEM method and chemical changes (moisture, iodine, peroxide, and acidic value) were investigated during storage periods. Results showed that variations in storage time and methyl cellulose concentration had significant effect on moisture content and peroxide value (P < 0.05). Also, in case of acidic value, a significant difference was observed between treatments so that pistachio at concentration of 2% showed the highest acidic value. The highest iodine value loss was related to a concentration of 0.1% and the lowest value was observed in the control sample.