Development of an edible coating based on chitosan-glycerol to delay ‘Berangan’ banana (Musa sapientum cv. Berangan) ripening process

Response surface methodology (RSM) was used to optimize the concentrations of chitosan and glycerol for coating Berangan banana (Musa sapientum cv. Berangan). The effects of main edible coating components, chitosan (0.5-2.5%, w/w) and glycerol (0-2%, w/w) on weight loss, firmness, total colour difference, total soluble solids content (TSS) and titratable acidity (TA) of coated banana were studied during 10 days of storage at 26±2°C and 40-50% relative humidity. Results showed that the experimental data could be adequately fitted into a second-order polynomial model with coefficient of determination (R2) ranging from 0.745 to 0.930 for all the variables studied. In general, the chitosan concentration appeared to be the most significant (P< 0.1) factor influencing all variables except for TSS. The optimum concentration of chitosan and glycerol were predicted to be 2.02% and 0.18%, respectively. Statistical assessment showed insignificant difference between experimental and predicted values

Evaluation of effectiveness of three cellulose derivative-based edible coatings on changes of physico-chemical characteristics of ‘Berangan’ banana (Musa sapientum cv. Berangan) during storage at ambient conditions

Three edible coating formulations, namely methyl cellulose (MC)-glycerol, sodium carboxymethyl cellulose (Na-CMC) - glycerol and hydroxypropylmethyl cellulose (HPMC) - stearic acid-glycerol with three concentrations of main edible components, MC (2, 3.5 and 5% w/v), Na CMC (0.1, 0.8 and 1.5% w/v) and HPMC (2, 4 and 6% w/v) were applied on the peel surface of green mature Berangan banana and stored at 26±2°C and 40-50% relative humidity. Results showed that coated banana using high concentration (1.5% w/v) of Na-CMC and 1% (w/v) glycerol had the least weight loss, total colour difference and total soluble solids content (7.14%, 6.06 and 3.95° Brix, respectively) and had the highest firmness and pH (20.42 N and 5.36) at day 10 of storage while the control samples were already completely ripened. This was followed by banana coated with low concentrations of Na-CMC (0.1% w/v)-glycerol (1% w/v) and HPMC (2% w/v)-stearic acid (1% w/v)-glycerol (1% w/v), MC and control. However, no significant difference was observed between banana coated with low concentration of MC (2% w/v)-glycerol (1.25% w/v) and control

Effects of pH, ions, and thermal treatments on physical stability of astaxanthin nanodispersions

In this work, astaxanthin nanodispersions were prepared using selected three component stabilizer system through a solvent-diffusion technique, with the particle size of 98.3 nm. The stability of produced nanodispersions against pH, salts, and heating were then evaluated. The produced nanodispersions exhibited good physical stability under wide ranges of pH (except around isoelectric point), sodium ion concentrations, and relatively high-temperature treatments (up to 60°C). However, formation of large particles was observed in either presence of calcium ions or higher thermal treatments (more than 60°C)

Effect of organic-phase solvents on physicochemical properties and cellular uptake of astaxanthin nanodispersions.

A simplex centroid mixture design was used to study the interactions between two chosen solvents, dichloromethane (DCM) and acetone (ACT), as organic-phase components in the formation and physicochemical characterization and cellular uptake of astaxanthin nanodispersions produced using precipitation and condensation processes. Full cubic or quadratic regression models with acceptable determination coefficients were obtained for all of the studied responses. Multiple-response optimization predicted that the organic phase with 38% (w/w) DCM and 62% (w/w) ACT yielded astaxanthin nanodispersions with the minimum particle size (106 nm), polydispersity index (0.191), and total astaxanthin loss (12.7%, w/w) and the maximum cellular uptake (2981 fmol/cell). Astaxanthin cellular uptake from the produced nanodispersions also showed a good correlation with their particle size distributions and astaxanthin trans/cis isomerization ratios. The absence of significant (p > 0.05) differences between the experimental and predicted values of the response variables confirmed the adequacy of the fitted models

Shelf life extension of banana using edible surface coatings conjugated with silver nanoparticles

Banana is one of the most favoured specialty tropical fruits and is very popular world-wide. Short shelf life of banana limits the storage, handling and transport potentials of the fruit. ‘Berangan’ banana (Musa sapientum cv. Berangan) is one of the most popular dessert cultivars and very highly priced in Malaysia. In the present study, edible coatings incorporated with silver nanoparticles as an alternative packaging were used in combination with low temperature (15+1'C and 65+10% RH) storage to extend the shelf life of banana. Green mature ‘Berangan’ bananas were coated using eight different edible coating formulations based on polysaccharides and proteins and stored at ambient conditions (26+2'C and 45+5% RH). Results of physico-chemical analysis of coated and control banana samples at day 10 of storage, indicated that edible coatings based on chitosan – glycerol – Tween 80 and sodium carboxymethyl cellulose (Na-CMC) – sodium caseinate (Na-Cas) – glycerol were more effective in slowing ripening process of banana among all different edible coating formulations selected based on literature review. Optimum concentrations of edible components of these two selected coating formulations were obtained using response surface methodology (RSM). Optimum concentrations of chitosan, glycerol and Tween 80 were 2.02%, 0.18% and 0.1% (w/w), and for Na-CMC, Na- Cas and glycerol, the optimum concentrations were 1.32%, 0.40% and 0.86% (w/w), respectively. Silver nanoparticles (SNPs), as a strong antimicrobial agent, was incorporated in the optimized edible coating formulations based on chitosan and Na-CMC. Due to high antimicrobial activity of edible coating based on chitosan, addition of small amount of SNPs (0 – 90 mg l-1) to this coating formulation, did not show significant (p> 0.05) effect on antimicrobial properties of resulting coating. The minimum bactericidal concentration (MBC) of SNPs to be incorporated into the edible coating formulation based on Na-CMC was 60 mg l-1. Application of the optimized edible coatings based on chitosan – glycerol –Tween 80 and Na-CMC – Na-Cas – glycerol with and without SNPs, at a concentration of 60 mg l-1, on green mature ‘Berangan’ banana followed by storage at both ambient (26+2'C and 7010% RH) and low temperature (15+1'C and 65+10% RH) conditions, indicated that all these three coating formulations could increase the shelf life of bananas stored at ambient and low temperatures by 3 days and 1 week, respectively. The maximum shelf life of control banana samples stored at ambient and low temperatures were 15 days and 5 weeks respectively. Results of the present study revealed that there was no significant (p> 0.05)differences in the most of physico-chemical, physiological and sensory attributes between banana samples coated with coating formulations based on Na-CMC – Na-Cas – glycerol with and without SNPs. The coating formulations based on chitosan and Na-CMC conjugated with SNPs, significantly (p< 0.05) inhibited growth of bacteria, yeasts and moulds on the banana surface, while the coating formulation based on Na-CMC without SNPs did not show inhibition effect on microbial growth, during storage at ambient and low temperatures. Evaluation of penetration of SNPs in both peel and pulp of coated banana samples with coating formulation based on Na-CMC – Na-Cas – glycerol – SNPs, indicated that during the ripening of coated banana samples, 92.5% and 90% of the SNPs which penetrated into the banana peel were detected in the outer layer of peel and the rest were detected in the inner layer of peel at both ambient and low temperature conditions, respectively. No SNPs were detected in the banana pulp, at both storage conditions. This could be due to the thickness and structure of banana peel. ‘Berangan’ banana is a thick-skinned banana and cell wall of its peel is composed of pectic, cellulose and hemicellulose components. These cell wall components of the peel can strongly create ionic bonds with SNPs and decrease their penetration rate through the banana peel. Thus, no SNPs could penetrate the pulp

Aloe vera leaf extract mediated green synthesis of selenium nanoparticles and assessment of their In vitro antimicrobial activity against spoilage fungi and pathogenic bacteria strains

Selenium as an essential trace element for the health of the humans was used to hydrothermally synthesis of selenium nanoparticle (Se NPs) using Aloe vera leaf extract (ALE). Effects of synthesis parameters namely; amount of ALE (1–5 ml) and amount of Na2SeO3 solution (10–30 ml), on the particle size and colour intensity of the solution containing Se NPs were studied using response surface methodology. FT-IR spectroscopy, UV-Vis spectrophotometry, DLS analyzer and TEM were used to determine the specifications of the ALE and synthesized Se NPs. Obtained results indicated that the ALE contained several bioactive compounds, which they had hydroxyl and amide І groups in their structures and these two functional groups had key roles in the reduction of the selenium ions to form Se NPs and stabilizing of them. Furthermore, spherical fabricated Se NPs using obtained optimum synthesis parameters, 4.92 mL of ALE and 13.03 mL of Na2SeO3 solution, had colour intensity, mean particle size, zeta potential and polydispersity index values of 3.0% a.u., 50 nm, -18 mV and 0.344, respectively according to the DLS analysis. The synthesized Se NPs had also high antibacterial and antifungal activities against 4 selected pathogenic bacteria and spoilage fungi strains

Selenium supplementation during fermentation with sugar beet molasses and Saccharomyces cerevisiae to increase bioethanol production

A bench scale submerged fermentation process was used to bioethanol produce using sugar beet molasses and Saccharomyces cerevisiae, as substrate and microbial strain, respectively. Effects of selenium amount on growth of S. cerevisiae and bioethanol production were evaluated. The obtained results indicated that growth of S. cerevisiae (manifested as turbidity intensity) in the samples containing 0, 5, 10, 15, 20 and 25 μg sodium selenite, during aerobic process, was 0.1707, 0.1678, 0.1679, 0.1664, 0.1627 and 0.160% a.u./h (after 14 h incubation), respectively. Statistical analysis based on compression test indicated that there were insignificant (p > 0.05) differences between growth rate of the yeast in the fermented samples containing S. cerevisiae and 5 to 25 μg selenium salt. Response surface methodology was utilized to evaluate effects of two fermentation parameters namely, amount of selenium (5-25 μg) and substrate brix (10-25°Bx) on the concentration (g/L) of produced bioethanol. Obtained results revealed that maximum bioethanol concentration (55 g/L) was achieved using 15 μg selenium and molasses with 25°Bx. Furthermore, results have also indicated that, without using selenium and using molasses with 25°Bx, bioethanol with concentration of 29 g/L was produced

Green approach in fabrication of photocatalytic, antimicrobial, and antioxidant zinc oxide nanoparticles – hydrothermal synthesis using clove hydroalcoholic extract and optimization of the process

Zinc oxide nanoparticles (ZnO NPs) were hydrothermally fabricated, using hydroalcoholic clove extract. GC-MS analysis demonstrated that Eugenol is the main bioactive compound of the prepared extract. Experiments were designed, based on the central composite design. The effects of different amounts of zinc nitrate (2–6 g) and clove extract (10–30 mL) were evaluated for antioxidant and bactericidal properties of the formed ZnO NPs using the response surface methodology. The attained results demonstrated that more desirable NPs with maximum antioxidant activity (85.23%) and bactericidal effect, against Escherichia coli and Staphylococcus aureus, as manifested in the diameter of formed clear zones of 11.12 and 12.11 mm, respectively, were resulted using 3.98 g of the zinc salt and 20.30 mL of the clove extract. Furthermore, XRD and SEM analysis results revealed that the fabricated ZnO NPs had a hexagonal shape with a particle size of 50 nm and could degrade 70% of methylene blue during UV radiation

Effectiveness of six different methods in green synthesis of selenium nanoparticles using propolis extract: Screening and characterization

Selenium nanoparticles (Se NPs) were fabricated with propolis hydro-alcoholic extract and six different methods, namely, hydrothermal, microwave irradiation, ultrasonication, UV radiation, self-assembling, and conventional heating. Results indicated that antioxidant activity, turbidity, pH, and brix values of the provided hydroalcoholic propolis extract were 85.8%, 2.235% a.u., 4.1, and 3.2°Bx, respectively. Gas chromatography analysis revealed that approximately 38 bioactive compounds were detected in the provided extract within 40 min of retention time, including chalcone. Results also revealed that each method had advantage in fabrication of Se NPs compared to others, but spherical Se NPs with overall appropriate physicochemical attributes of particle size (50–60 nm), polydispersity index (0.362), zeta potential (−41.8 mV), maximum broad absorption peak (321 nm), and antioxidant activity (12.4%) were synthesized using the ultrasonication method with a frequency of 20 kHz and a power of 300 W for 10 min

Evaluation of the saponin green extraction from Ziziphus spina-christi leaves using hydrothermal, microwave and Bain-Marie water bath heating methods

Saponin as a biosurfactant was extracted from Iranian Ziziphus spina-christi leaves using three green extraction methods namely, autoclave, microwave and Bain-Marie heating methods. In this study, three solvents namely, methanol, ethanol and water were used to extract saponin. The results revealed that water, as compared to the methanol and ethanol, is a more suitable solvent to extract saponin from the Z. spina-christi leaves. The obtained results indicated that saponin extraction using autoclave provided more suitable physico-chemical properties along with a better yield. In fact, maximum foam volume (12.56 cm3), color intensity (3.24% absorbance unit [a.u.]) and turbidity (1.39% a.u.) of the extracted solutions was obtained by the autoclave heating method. The high performance liquid chromatography (HPLC) results also illustrated that the amounts of extracted saponin using autoclave, Bain-Marie and microwave heating extraction methods were 14, 8.8 and 1.3 (intensity mV), respectively. The results obtained by HPLC were reconfirmed by Fourier transform infrared (FT-IR) analysis