Antimicrobial potato starch — based films incorporating lactic acid

A multi-layer barrier coating technology was developed using nano-fibrillated cellulose (NFC) alongside a hydrophobic, paraffin-free biowax for manufacturing an eco-friendly functional packaging paper. Anionic NFC was prepared by isolating hardwood-bleached kraft pulp (Hw-BKP) using a micro-grinder, and cationic NFC was prepared by the quaternization reaction of the anionic NFC. Thereafter, a three-layer barrier-coated paper was manufactured using cationic and anionic NFCs and biowax. The air permeability and water vapor transmission rate (WVTR) of the three-layer barrier-coated paper were measured, and its coverage and coating layer structure were observed by scanning electron microscopy (SEM). The air permeability of the three-layer barrier-coated paper was more than 15,000 s and those WVTR was 67.1 g/m2/day. Its coverage and surface were considerably uniform and smooth. Thick and effective barrier coating layers were formed as indicated by SEM images. Therefore, it was concluded that a multi-layer barrier-coated paper with considerably high barrier properties could be produced using cationic and anionic NFCs with high gas barrier properties and biowax with high moisture barrier properties. Further, the structure could be used as a functional packaging paper with high barrier properties.

Lactic acid (LA) is an important platform chemical due to its significant applications in various fields and its use as a monomer for the production of biodegradable poly(lactic acid) (PLA). Free LA production is required to get rid of CaSO4, a waste material produced during fermentation at neutral pH which will lead to easy purification of LA required for the production of biodegradable PLA. Additionally, there is no need to use corrosive acids to release free LA from the calcium lactate produced during neutral fermentation. To date, several attempts have been made to improve the acid tolerance of lactic acid bacteria (LAB) by using both genome-shuffling approaches and rational design based on known mechanisms of LA tolerance and gene deletion in yeast strains. However, the lack of knowledge and the complexity of acid-tolerance mechanisms have made it challenging to generate LA-tolerant strains by simply modifying few target genes. Currently, adaptive evolution has proven an efficient strategy to improve the LA tolerance of individual/engineered strains. The main objectives of this article are to summarize the conventional biotechnological LA fermentation processes to date, assess their overall economic and environmental cost, and to introduce modern LA fermentation strategies for free LA production. In this review, we provide a broad overview of free LA fermentation processes using robust LAB that can ferment in acidic environments, the obstacles to these processes and their possible solutions, and the impact on future development of free LA fermentation processes commercially.

A new mathematical model is proposed to analyze the mass transfer behavior in lactic acid fermentation using immobilized cells entrapped in calcium alginate. The model is comprised of material balance equations for glucose, free lactic acid, and several ions. The dissociation rate of lactic acid (rdiss) is involved in the proposed equations. To solve the equations numerically, a modified calculating method is proposed. Through model analysis, the possible mass transfer behavior in the gel bead was discussed. The model is validated by comparisons with the experimental results obtained from batch and continuous fermentation. The simulations using the model were made to investigate the mass transfer limitation in the gel beads. The results showed that the cell density gradient was formed in the gel beads and it was caused by the accumulation of the inhibitory product (free lactic acid), not by substrate starvation. Moreover, unusual mass transfer behavior of lactate ion in the immobilization support was pointed out.

The study explores composite polysaccharide films made from plantain pulp starch and chitosan, incorporating extracts from Panadol leaves of Plectranthus barbatus and Plectranthus caninus to improve physicochemical and antimicrobial properties. Plantain pulp starch was extracted using 25% NaOH and films were created via solvent casting by combining equal volumes of 5% starch and 2.5% chitosan. Phytochemical screening of the ethanolic leaf extracts employed spectroscopic methods. Evaluations included antioxidant capacity, total phenolic and flavonoid contents, water solubility, swelling indices, water vapour transmission rates and optical properties. Antimicrobial activity was tested using the disk diffusion method and plate count agar. Antioxidant activities showed % DPPH inhibition of 74.60 ± 0.05 and 64.77 ± 0.07 for Plectranthus barbatus and Plectranthus caninus, with phenolic contents of 86.56 ± 0.03 and 69.59 ± 0.04 mg/g gallic acid equivalents, and flavonoid contents of 91.25 ± 0.005 and 74.49 ± 0.003 mg/g quercetin equivalents respectively. The composite films exhibited increased opacity, density and moisture content alongside decreased swelling indices. Water solubility varied by component with no significant difference in water vapour transmission rates among the films. Both gram-positive and gram-negative bacteria were inhibited by the leaf extracts. The starch-chitosan composite films with leaf extracts demonstrated enhanced physicochemical and antimicrobial properties making them suitable for sustainable food packaging.

This study investigates the synthesis of potato starch elastomers reinforced with silicon dioxide (SiO2) and citric acid as a crosslinking agent to enhance their mechanical and barrier properties. Surface morphology analysis using optical microscopy revealed that pure potato starch films had uneven surfaces. However, higher SiO2 concentrations increased roughness, while citric acid crosslinked films displayed smoother surfaces overall. Water vapor transmission rates (WVTR) indicated that native starch films were highly hydrophilic, while SiO2 incorporation and citric acid crosslinking significantly reduced WVTR of 17% (30% lower than native film), enhancing the barrier properties. Tensile strength testing revealed that citric acid crosslinking increased the tensile strength by 25%, while SiO2 further reinforced the films but decreased elasticity by 15%. SiO2 had little impact on degradation rates, while citric acid crosslinking delayed microbial growth, extending film longevity by 20%. Biocompatibility assays using SiHa, HT-29, and HEK 293 cell lines revealed that the films had varying degrees of cell confluency. Films with both SiO2 and citric acid showed improved confluency (20% higher) compared to films containing only SiO2. However, citric acid alone resulted in the highest confluency (95% viability), suggesting its significant role in biocompatibility. This eco-friendly approach demonstrates substantial advancements in film properties, offering potential applications in diverse biomedical industries.

<p>The use of blends containing biodegradable polymers like starch and poly (lactic acid) (PLA) has gained considerable attention, especially for the food packaging production. Current research has also highlighted the use of chitosan because their antimicrobial activity, biodegradability and applicability in the production of active biodegradable food packaging. The objective of this work was to produce cassava starch and PLA sheets incorporated with chitosan by flat extrusion process (calendering-extrusion), and evaluate the mechanical, water vapor barrier and microstructural properties. In order to simplify the obtainment of the material reducing processing steps, all components of the blend were homogenized in one step extrusion The incorporation of chitosan in the starch/PLA sheets decreased significantly the tensile strength, Young's modulus, elongation at break and density. In addition, the scanning electron microscopy images showed the formation of non-homogeneous mixtures with the presence of pores between the blend compounds, and this fact affected the water vapor barrier properties increasing water vapor permeability, solubility and diffusion coefficients. It was possible to conclude that although the incorporation of chitosan to the starch/PLA sheets has not contributed to obtain materials with suitable properties, it was able to produce them by calendering-extrusion process in pilot scale. Studies about chitosan incorporation in starch and PLA sheets still needed.</p><p> </p><p>DOI: 10.14685/rebrapa.v6i1.208</p><p> </p>

Water vapor transmission rate was measured on uncoated and ethyfeae-plasma-coated whey (65-93.5% whey protein), on chitosan and starch films and on aluminum-coated chitosan. Surface hydrophobicity was assessed by contact angle measurements, and X-ray photoelectron spectroscopy was used to characterize the coatings. The water vapor transmission rate through the uncoated polymer films was highest for starch and lowest for chitosan. Whey showed intermediate water permeability, with the sample containing 65% whey-protein having the lowest water vapor transmission rate. An improvement in water vapor barrier properties was observed only for the aluminum-coated sample and not for any of the polyethylene-coated samples. It is observed that the penetrating water caused the substrate to swell and the polyethylene coating layer to crack. According to profilometry, the thickness of the polyethylene coating layer was 0.1-1 μm after 15 min exposure time. The coating was hydrophobic and contained almost exclusively carbons typical of linear or crosslinked hydrocarbons. It is suggested that the observed decrease in hydrophobicity with time during the contact angle measurements is due to the reorientation at the surface of carbonyls present in small amounts in the coating.

Morus alba L. (Moraceae) leaves are used effectively to treat fever, protect liver from damage, strengthen the joints, facilitate discharge of urine in Turkey folk medicine. In this study we aimed to determine in vitro antioxidant and antimicrobial activity with GC/MS analysis of the Morus alba L. leaves. Dried plant leaves samples are milled and extracted with distilled water and ethanol in Soxlet machine. After extraction, extract samples were concentrated in rotary evaporator machine. Total antioxidant status values were determined as mmol Trolox Equivalent/L spectrophotometrically by using Erel’s method. Sterile extracts used to avoid contamination in antimicrobial activity test. As test microorganisms Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Pseudomonas aeroginosa (ATCC 27853), Candida albicans (ATCC 90028) were used. Antimicrobial activity was determined with disk diffusion method. We used ethanol extracts of samples in GC/MS analysis. Ethanol and distilled water extracts showed antioxidant activity in different rate. Besides, ethanol extracts have an antimicrobial activity but water extracts have not antimicrobial activity on our test microorganisms. We determined four compounds (9,12,15-octadecatrienoic acid, ethyl ester, linolenic acid ethyl ester, gibberellic acid) with GC/MS analysis in ethanol extracts. In this researh we enlightened antimicrobial and antioxidant activities with GC/MS analysis of Morus alba L. leaves. So this research support of using this plant leaves in pharmacological and medical processes. Keywords: Antioxidant activity; Antimicrobial activity; GC/MS analysis; Morus alba L., extraction DOI: 10.17350/HJSE19030000006 Full Text:

Transparent, high gas barrier films are crucial in the medical, food, and electronic industries. The main properties required for electronic devices such as flexible displays include transmittance of >90% and oxygen transmission rates (OTRs) and water vapor transmission rates (WVTRs) of 10–3 to 10–6 cc(g) m–2 day–1. Herein, we report reduced graphene oxide (rGO)/inorganic and organic/inorganic composites coated on poly(ethylene terephthalate) (PET) film with superior oxygen and water vapor barrier properties and high transmittance. The OTR (at 23 °C, 0% relative humidity) and WVTR (at 37.8 °C, 100% relative humidity) values of the composite films (140 μm) decreased by 8 × 104 times and 6.71 × 102 times, respectively, relative to those of the PET substrate film (125 μm). The transmittance of the composite films at 550 nm was 84%, corresponding to only a 9% decrease compared to that of the PET film. Additionally, with only nanolayers of SiOxNy (100 nm) and rGO (13 nm) coating on the PET substrate, the OTR and WVTR were reduced by 2000 times and 470 times, respectively. A polyvinylidene fluoride/rGO (PVDF/rGO) layer on the SiOxNy/PET substrate showed 8.8 × 105 times lower oxygen permeability and 1.6 × 104 times lower water permeability compared to those of PVDF/rGO on the PET substrate, implying that the inorganic SiOxNy nanolayer is crucial, affording a synergistic effect toward the barrier film. The gas permeabilities of the composite films strongly depend on the design of the coating structure, rGO content, and blend ratio of PVDF and PMMA; this allows efficient control of the nanodefects of the composite film. This study shows the significance of inorganic materials and the synergistic effect of composites on barrier films, which are required for applications in organic electronic devices and packaging materials.

The main objective is to produce an electro spun mat from ardil fibers in combination with polyvinyl alcohol which can be used for medical applications. Ardil fibers are the fibers extracted from the protein obtained from the defatted oil cake of groundnut. The inherent anti-microbial activity of ground nut allows the use of ardil fibers for medical applications. Since ardil fibbers are not capable of forming fibers of its own by electro spinning, they are used in blend with polyvinyl alcohol. Polyvinyl alcohol is chosen mainly because of its biocompatibility, biodegradability and non-toxicity. The electro spun mat produced from ardil and polyvinyl alcohol was checked for anti-microbial activity so that it can be used for medical applications and X-ray diffraction was seen to check the presence of proteins which was absolute. Other test such as moisture vapor transmission rate (MVTR) and thermo gravimetric analysis (TGA) were also conducted to check whether the produced electro spun mat can be used for the required end use. MVTR is checked to check the breathability of the mat and control of moisture. The MVTR is between the acceptance levels which can be used for medical applications. TGA is to check absorption and adsorption. From the results obtained from different results, it is obvious that the produced mat can be used for medical applications.

This study focused on the development of high‐performance bio‐based films from chitosan and rice husk nanocellulose, reinforced with either nano‐magnesium oxide (MgO) or neem oil. The films were evaluated for strength, crystallinity, thermal stability, swelling degree, solubility, water vapor transmission rate, moisture retention, apparent density, and antimicrobial and antioxidant activities. Adding nano‐MgO significantly enhanced film crystallinity by 84.9%, increased tensile strength and Young's modulus, and improved thermal stability up to 265°C while reducing swelling and biodegradability (33.07% compared to 35.71% for chitosan‐nanocellulose). The addition of MgO increased surface roughness, which influenced water uptake and barrier properties. However, neem oil improved flexibility, elongation at break (15.29%), antimicrobial activity against E. coli , antioxidant capacity (70.16% DPPH scavenging), and moisture management, but decreased crystallinity and thermal stability. Solubility and swelling behaviors were moderated by the interactions among chitosan, nanocellulose, and the fillers. Apparent density analysis indicated that MgO increased density by filling polymeric spaces, whereas neem oil slightly reduced stiffness without significantly affecting density. The functional properties of chitosan‐nanocellulose films could be tailored through selective incorporation of MgO or neem oil, achieving an optimized balance of mechanical, thermal, barrier, and bioactive performance, making them promising candidates for sustainable and effective food packaging applications.

Poly(lactic acid)/halloysite nanotube nanocomposites containing epoxidized natural rubber were prepared using melt compounding, followed by compression molding. The mechanical properties of the nanocomposites were determined by tensile, flexural, and Charpy impact test. The addition of 15 wt.% epoxidized natural rubber into poly(lactic acid)/halloysite nanocomposites increased the impact strength to about 340%. However, the tensile modulus, flexural modulus, tensile strength, flexural strength, and elongation at break of poly(lactic acid)/halloysite nanotube were decreased in the presence of epoxidized natural rubber. Water absorption tests were performed at three immersion temperatures (i.e. 30, 40, 50℃). The equilibrium water absorption ( Mm), diffusion coefficient ( D), and activation energy ( Ea) of water diffusion of the poly(lactic acid)/halloysite nanotube/epoxidized natural rubber nanocomposites were determined. The activation energy of poly(lactic acid)/halloysite nanotube was increased from 14.7 to 31.8 kJ/mol by the addition of epoxidized natural rubber. The percentage retention of impact strength of poly(lactic acid)/halloysite nanotube/epoxidized natural rubber nanocomposites after exposure to water absorption is higher than 80% for the one containing 5 and 10 wt.% epoxidized natural rubber loading.

Enzymatic synthesis of AHA derivatives for cosmetic application

The objective of this research was to use chitosan coating for shelf life extension of refridgerated ready-to-eat food product. The research was separated into 3 sections. Firstly, the optimum packaging material and condtion for packaging of brioled boneless por1<. (BBP) was determined by using polypropylene bag under atmospheric air (OPP) and polyamide bag under atmospheric air (PA) and vacuum condition (PA-V) and stored at 2 ± 1 °C. The results suggested that PA-V could maintain qualities including color, texture, pH, peroxide values (POV) and organoleptic qualities of BBP better than PA and OPP. Therefore, PA-V was used for further experiment. Secondly, the optimum method for preparation of chitosan coating was determined by using different solvents including lactic acid 1% (wlv) and acetic acid 1% (w/v) and different concentrations of plasticizer including 0, 10, 20 and 30 % w/w of chitosan. It was found that using acetic acid, the chitosan film had higher tensile strength (TS), while thickness, elongation at break (% EAS) and water 'vapor transmission rate (WVTR) were not different from those using lactic acid. It was also found that 20 % plasticizer was optimum to be used for preparing chitosan film because the film had higher % EAB, while maintaining thickness, TS, and WVTR. Lastly, the effect of using chitosan coating on qualities and shelf life of BBP was determined by coating the BBP with chitosan concentrations of 2.0 % w/v (Coat-A) and 2.5 % w/v (Coat-B), SSP without chitosan coating was used as Control. All samples were then packaged in PA-V and stored at 2 ± 1°C. It was found that BBP coated with chitosan could maintain color, texture, pH, POV and organoleptic qualities better than Control. The results suggested that chitosan coating could inhibit microbial growth and lipid oxidation of the product and thus extending the shelf life of the SSP, Control samples had had shelf life of less than 21 days, while BBP coated with chitosan had shelf life of up to 28 days .

The water vapour transmission rates (WVTR) through solvent cast polymer films prepared from cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate have been determined. They were influenced by the relative humidity, the substituent type and the extent of substitution. Increasing the relative humidity from 32 to 90% increased the WVTR 3 to 5 times depending on the polymer used. The WVTR increased in the order of butyrate less than propionate less than acetate. An increase in the extent of substitution with acetyl and/or butyryl groups resulted in an exponential decline in the WVTR.