Abstract Modification of composite components has been proposed as a tool to improve their functional properties. The present work studied crosslinking of a starch/oat hull mixture by reactive extrusion with sodium trimetaphosphate (STMP), for application in composites with polylactic acid (PLA). The treated mixture was characterized regarding degree of substitution, FT-IR, and thermal properties. The native and modified mixtures were processed by injection molding, together with PLA and glycerol. The microstructure, mechanical properties, shrinkage, density, and thermal properties of the composites were determined. The FT-IR results, increase in phosphorus content and thermal stability after starch/fiber mixture treatment with STMP suggested the occurrence of crosslinking. Better interfacial adhesion between oat hulls and the polymeric matrix was observed in electron micrographs of the composites containing the modified components. Slight decreases in tensile strength and modulus were observed in the modified composites, suggesting that extrusion and subsequent milling may have broken some structures/linkages.

Abstract The aim of this work was to study the relationship of chain size of partially hydrolyzed PVA blended with starch in properties of biodegradable sheets produced by thermoplastic extrusion. It was also studied the effect of extrusion temperature profile to determine the better PVA chain size and temperature profile to produce biodegradable sheets through a factorial design. The processability and the mechanical, thermal, optical, and microstructural properties of the biodegradable sheets were adequate, indicating that PVA/cassava starch blends have potential to replace conventional non-biodegradable polymers. Tensile strength and Young’s modulus ranges from 1.0 to 2.6 and 3.0 to 6.9 MPa respectively, the elongation at break ranges from 42 to 421%. It was not possible to state a conclusive relationship between PVA molecular weight and the materials properties, but in general, PVA with medium molecular weight and high extrusion temperature profile promote an increase of mechanical properties of the sheets.

Resumo: O objetivo deste trabalho foi avaliar períodos de armazenamento em câmara fria e longevidade pós-colheita da uva apirena 'BRS Vitória', submetida à aplicação do indutor de resistência a doenças acibenzolar-S-metil (ASM). Os cachos foram tratados, ou não, com ASM a 1%, individualizados em bandejas de plástico e mantidos em câmara fria a 2±1ºC e à alta umidade relativa por três períodos (30, 45 e 60 dias), seguidos por cinco dias de avaliação da vida de prateleira, a 22±2ºC. Após cada período de armazenamento, avaliou-se a incidência de mofo-cinzento (Botrytis cinerea), e realizaram-se as análises físico-químicas dos cachos. Utilizou-se o delineamento completamente casualizado, com quatro repetições, em dois arranjos fatoriais 2x3: um com avaliação de ASM e períodos de armazenamento em câmara fria; e outro, de ASM e períodos de armazenamento em câmara fria + vida de prateleira. O ASM não alterou as características físico-químicas dos cachos, e a incidência de mofo-cinzento foi inferior a 1% em todos os tratamentos. A perda de água dos cachos aumentou com os períodos de armazenamento. Mesmo sem a aplicação de ASM, a uva 'BRS Vitória' pode manter sua qualidade pós-colheita por até 60 dias de armazenamento em câmara fria, além de mais cinco dias de vida de prateleira em bandejas de plástico.

Abstract: The objective of this work was to evaluate cold storage periods and postharvest longevity of the seedless table grape 'BRS Vitória' subjected to the application of the disease-resistance inducer acibenzolar-S-methyl (ASM). Bunches were treated or not with 1% ASM, placed individually in plastic clamshell trays and stored in a cold chamber at 2±1ºC, at a high relative humidity, for three periods (30, 45, and 60 days), followed by a 5-day period of shelf life in plastic clamshells, at 22±2ºC. After each storage period, gray mold (Botrytis cinerea) incidence was evaluated, and the physicochemical analysis was performed. A completely randomized design, with four replicates, was used in two 2x3 factorial arrangements: one evaluating ASM application and cold storage periods; and another, ASM and cold storage + shelf-life periods. ASM did not change the physicochemical characteristics of the bunches, and the incidence of gray mold was lower than 1% in all treatments. Water loss from bunches increased with storage periods. Even without ASM application, 'BRS Vitória' grape can preserve its postharvest quality for up to 60 days of cold storage, plus five days of shelf life in plastic clamshells.

Abstract This study aimed to prepare whey protein-based films incorporated with oregano essential oil at different concentrations, and evaluate their properties and antimicrobial activity. Films were more flexible with increasing the concentration of oregano oil and water vapor permeability was higher in the films with oregano oil. Increasing the concentration of essential oil decreased the water solubility. The solubility of control film and film with 1.5% oregano oil was 20.2 and 14.0%, respectively. The addition of 1% of oregano oil improved the resistance of the films. The tensile strength for the control film was 66.0 MPa, while for the film with 1% of oregano oil was 108.7 MPa. Films containing 1.5% oregano oil showed higher antimicrobial activity. The zone of inhibition ranged from 0 to 1.7 cm. The results showed that the whey protein-based films incorporated with oregano essential oil has potential application as active packaging.

AbstractThe demand for renewably sourced biodegradable materials has increased the need to produce materials that combine appropriate functional properties at competitive costs. Thermoplastic starch and polyester blends are an interesting alternative to current materials due to the low cost of starch and the functional properties and processability of the resulting blends. Producing thermoplastic starch (TPS) requires using a plasticiser at concentrations between 20 and 30%wt (in relation to starch). Glycerol is the most common plasticiser due to its high plasticising capacity and thermal stability at processing temperatures. The objective of this study was to evaluate glycerol waste from the biodiesel industry, with different degrees of purification, as plasticisers for TPS / poly (butylene adipate-co-terephthalate) (PBAT) blends. Different purities of glycerol produced films with similar mechanical, optical and barrier properties to those made with purified glycerol (99.7%). Therefore, crude glycerol is a renewable alternative plasticiser that reduces the cost of plasticisation by 6-fold.

The production of plant seedlings has traditionally used polyethylene bags, which are thrown out in the soil or burned after transplant because the large amount of organic material attached to the bags makes recycling difficult. Additionally, when a seedling is taken from the bag for transplant, there is the risk of root damage, which compromises the plant’s development. In this study, we developed biodegradable bags to be used in seedling production, and we verify their influence on the development of Brazilian ginseng (Pfaffia glomerata (Spreng) Pedersen), when the plant is planted without being removed from the bag. Both black and white biodegradable bags remained intact throughout the seedling production period (60 days). After being transplanted into containers (240 days), they were completely biodegraded, and there was no significant difference between the dry mass of these plants and that of plants that were transplanted without the bags. The plants that were cultivated without being removed from the polyethylene bags had root development difficulties, and the wrapping showed no signs of degradation. The use of biodegradable films is an alternative for the production of bags for seedlings, as these can then be transplanted directly into the soil without removing the bag, reducing the risk of damage to the roots during the moment of transplant.