Epoxidation of modified natural plasticizer obtained from rice fatty acids and application on polyvinylchloride films

In recent years, much research effort has been driven to develop alternative plasticizers for medical and commodity plastic materials. In this study, a modified natural plasticizer, synthesized by esterification of rice fatty acids, was modified by epoxidation with peroxy acid generated in situ. Two natural epoxidized plasticizers were obtained, using peracetic acid (NP‐Ac) and peroctanoic acid (NP‐Oc) as reagent. PVC films after addition of these natural epoxidized plasticizers presented fairly good incorporation and plasticizing performance, as demonstrated by results of mechanical properties, T_g values (as shown by DSC), optical microscopy, exudation, and migration tests, FTIR and X‐ray diffraction obtained for plasticized PVC films. NP‐Ac plasticizer presented enhanced plasticizing performance compared with NP‐Oc, probably due to a higher epoxidation degree obtained in the reaction with peracetic acid. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Biocomposite membranes of sodium alginate and silk fibroin fibers for biomedical applications

Biocomposite membranes from biodegradable and biocompatible natural polymers were prepared from sodium alginate solution reinforced with silk fibroin fibers in several fiber content by casting and solvent evaporation. The properties of these biocomposites were investigated by scanning electron microscopy, swelling test, water vapor transmission, mechanical and thermal analyses, and cytotoxicity test. A biocomposite with uniform fiber dispersion and good fiber–matrix interaction was obtained through the incorporation of fibroin fibers in the alginate membrane, even though the fibers were used without any surface treatment to enhance the interfacial adhesion. The incorporation of fibroin fibers improved the tensile strength and also provided a new property to the alginate, that is, the resistance to tear. Moreover, the use of silk fibroin fibers in polymeric composites can result in a material with adequate characteristics for application in the biomaterial field, especially as wound dressings, because of its nontoxic effect to cells, flexibility, and resistance to tear. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3451–3457, 2013     

Hybrid alginate–copper sulfate textile coating for coronavirus inactivation

The sanitary crisis caused by the SARS-CoV-2 has increased the demand for bioactive materials to mitigate coronavirus spread. The use of masks has been reported as an essential strategy to prevent coronavirus transmission, but they can become contaminated rapidly after use. Metals species containing compounds, especially those from the copper group, present properties that can be explored to suppress viral activity. Natural polymers, like alginate, can improve biocompatibility and adjust metal ion availability on hybrid coatings. This study assesses iron, copper, silver, and gold salts and their combination with biopolymers to design surfaces with virucidal properties. Viral inactivation assays with MHV-3 coronavirus strain and cytotoxicity tests with L929 cells were conducted to the hybrid coatings on polypropylene masks. These coatings were characterized by scanning electron microscopy with energy dispersive spectroscopy, Fourier-transform infrared spectroscopy with attenuated total reflectance device, and atomic absorption spectroscopy techniques. Multilayer coatings of alginate–copper sulfate presented 99.99% viral inactivation in a timely release of copper ions.     

Edible mushrooms’ enrichment in food and feed: A mini review

Dietary fibres and high fibre-containing foods have been a huge attraction among researchers and nutraceutical industries due to their health-promoting benefits. From Greek and Roman times, edible mushrooms are considered the ‘elixir of life’ and are often stated as a new source of dietary fibre. Containing rich sources of essential amino acids and polysaccharides, mushrooms are viewed as an advantage over protein sources of both animal and plant origin. Additionally, the ability of mushrooms to grow under controlled conditions and attain high yield in a short span has made this added-value food of extreme interest. Nowadays, mushrooms and their by-products have been used to fortify various food products as well as for use in animal feed owing to their bioactive, therapeutic and nutritional value. Hence, this review intends to highlight the current knowledge on edible mushrooms and their waste for food and feed enrichment and nutritional purposes, along with their role in human and animal diet.     

Effects of microwave and hot‐air drying methods on colour, β‐carotene and radical scavenging activity of apricots

The effects of drying by microwave and convective heating at 60 and 70 °C on colour change, degradation of β‐carotene and the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) scavenging activity of apricots were evaluated. Microwave heating reduced significantly the drying time (up to 25%), if compared with convective one, also owing to the higher temperature reached during the last phase of the process, as monitored by infrared thermography. Colour changes of apricot surface, described with lightness and hue angle, in both drying methods followed a first‐order reaction (0.927 ≤ R² ≤ 0.996). The apricots dried by microwave were less affected by the darkening phenomena. The evolution of β‐carotene in fresh apricots (61.2 ± 5.6 mg kg^?1 d.w.) during the drying highlighted a wider decrease (about 50%) when microwave heating was employed for both the temperatures used. Radical scavenging activity increased (P < 0.05) in all dried samples except for hot‐air dried apricots at 60 °C.     

Bioactive action of β‐glucosidase enzyme of Bifidobacterium longum upon isoflavone glucosides present in soymilk

Bioconversion of isoflavone glucosides and antioxidant activity by probiotic strain (Bifidobacterium longum) during soymilk fermentation was investigated, as well as partial characterisation of the produced enzyme β‐glucosidase. The enzyme has higher affinity for genistin than for other substrates assayed. Maximum activity occurred at 42 °C and at pH 6.0; keeping 70–80% of activity for 60 days stored at low temperatures. Bifidobacterium longum grew well in soymilk (8.26 log CFU mL^?1 and pH of 3.9 at 24 h) and were produced in good quantities of organic acids. High hydrolysis degree of isoflavone glucosides (81.2%) was observed at 24 h. Enhancements in bioactivity were assessed in fermented soymilk by monitoring the radical‐scavenging activity, antioxidant activity and DNA protective action. The use of probiotic Bifidobacterium strain as β‐glucosidase producer increased bioactive isoflavone content and demonstrated that this enzyme plays a key role in the bioavailability of soymilk isoflavones, reducing the bioconversion time compared to other studies.     

A New Label-Free Impedimetric Affinity Sensor Based on Cholinesterases for Detection of Organophosphorous and Carbamic Pesticides in Food Samples: Impedimetric Versus Amperometric Detection

Due to their increasing use in agriculture, the presence of pesticide residues in food and water currently represents one of the major issues for the food safety. Among the pesticides, organophosphate and carbamate species are the most used, and their toxicity is mainly due to their inhibitory effect on acetylcholinesterase (AChE). For this reason, a monoenzymatic acetylcholinesterase impedimetric biosensor was developed in order to sensitively detect carbamate and organophosphate compounds with a very fast response. The working principle of the AChE biosensor exploits the capability of carbamate and organophosphate pesticides to form a stable complex with the enzyme, which causes an impedimetric change. The impedimetric biosensor showed a linearity between 5 and 170 ppb for carbamates and 2.5–170 ppb for organophosphate compounds, with a reproducibility (RSD%) interelectrode equal to 4.8 and 3.1% for organophosphates and carbamates, respectively. Moreover, the common amperometric evaluation of AChE inhibition degree was correlated to the impedimetric changes of the electrode surface, showing a good correlation (R ² = 0.99 for carbamates and R ² = 0.98 for organophosphates) between the two methods. In contrast to amperometric evaluation that needs a response time of 20 min, impedimetric detection requires only 4 min. Finally, the impedimetric biosensor was used to measure carbaryl and dichlorvos spiked in different concentrations in tap water and lettuce samples, showing a recovery near to 100% for all concentrations and for both pesticides.     

Bacillus cereus,Bacillus thuringiensis and Bacillus mycoides differentiation using a PCR-RE technique

A method was developed to differentiate between Bacillus cereus, Bacillus mycoides and Bacillus thuringiensis using the polymerase chain reaction combined with a restriction endonuclease (PCR-RE) technique. This fast and simple protocol, applied to pure culture strains, was developed using the gyrB DNA sequence, as previously proposed by other authors. Strains from international collections were used to optimize the method which was then applied to the identification of strains isolated from food samples. Amplifications were specific for the B. cereus group. Only Staphylococcus aureus gave the same size PCR product, but it was easily differentiated from strains in the B. cereus group by using restriction analysis, based on digestion with the RsaI, Sau3AI and EcoRI endonucleases. Specific amplifications and good differentiations were obtained using pure strains, suggesting the possibility of using the method described to identify the B. cereus group directly in food samples.     

Antioxidant effect of dittany (<Emphasis Type="Italic">Origanum dictamnus</Emphasis>) in pre-cooked chicken meat balls during chill-storage in comparison to rosemary (<Emphasis Type="Italic">Rosmarinus officinalis</Emphasis>)

Dittany (Origanus dictamnus L.) has been compared with rosemary (Rosmarinus officinalis L.) as an antioxidant in pre-cooked meat balls made from chicken breast and added 0.50% salt during chill storage for up to ten days packed in atmospheric air. For an addition of 0.10% of dried leaves, dittany yielded protection of the product against oxidation a little less efficiently but comparable to dried rosemary added at the same concentration. For addition of 0.050%, dittany was less efficient than rosemary, while dittany at this concentration protected vitamin E against degradation in the product during storage even better than rosemary.     

Influence of<Emphasis Type="Italic"> Lactobacillus plantarum</Emphasis> on<Emphasis Type="Italic"> Staphylococcus aureus</Emphasis> growth in a fresh vegetable model system

The influence of a Lactobacillus plantarum (B₄) on the growth of Staphylococcus aureus (Sa₄) was verified by impedometric methods in a suitable model reproducing the characteristics of fresh vegetables. The inoculum size of the single strains and their growth temperature were varied according to a Central Composite Design. The results obtained via statistical analysis showed that the temperature affected the growth of both S. aureus and L. plantarum strains. The pathogenic strain, independently of its inoculum size, was inhibited by L. plantarum at all the tested temperatures. A proper combination of specific lactic acid bacteria and storage temperature should improve the safety of the vegetable products.