Influence of pinhão starch and natural extracts on the performance of thermoplastic cassava starch/PBAT extruded blown films as a technological approach for bio-based packaging material.

Films were produced using the blown extrusion method from blends made with cassava and pinhão thermoplastic starch, compostable polyester (poly(butylene adipate co-terephthalate, PBAT) and natural extracts (rosemary and green tea). The effect of the incorporation of the extracts and the type of starch added in the film properties were investigated following the mixture design (23 ) approach. Regression models and response surface curves were generated to predict the film properties. The effect of the cold storage (6 °C and 17% of humidity relative, for 60 days) on the film properties was also investigated in order to simulate future applications. All the properties were mainly influenced by the extract type. The incorporation of the extracts decreased the lightness parameter and the films produced with green tea extract were more opaque than those made with rosemary. Starch/rosemary blends were more flexible, while the extract type did not have a significant effect on tensile strength (TS). Film elongation (ELO) ranged from 520% to 719% and might be comparable to some synthetic polymers. The water vapor permeability was improved in approximately 14% with addition of the extracts. The storage conditions, on the one hand, increased the TS, elastic modulus, and opacity of films and, on the other hand, decreased the elongation parameter. The thermal stability of films was not modified by adding extracts or varying the starch type. The results demonstrated that pinhão/cassava/PBAT blends and the natural extracts are a good alternative matrix to produce packagings with adequate mechanical and barrier properties. PRACTICAL APPLICATION: Extruded films produced from cassava or pinhão starch, poly(butylene adipate co-terephthalate) (PBAT) and natural extracts show technological potential to be used as active packaging for food products. Pinhão starch is a great alternative substitute to cassava starch and the incorporation of the commercial compostable polymer (PBAT) is necessary in order to confer suitable mechanical properties to extrusion process. The extrusion blown method, a process widely used by plastic industries, allows the scale-up of bio-based packagings for industrial scale.

Valorization of Euterpe edulis Mart. agroindustrial residues (pomace and seeds) as sources of unconventional starch and bioactive compounds.

Juçara fruit pomace is one of the most abundant byproducts of the pulp-making process, generally discarded despite their attractive nutritional content. In this sense, this study aimed to investigate the potential of juçara fruit pomace as an alternative source of starch and natural dyes. Starch extracted from juçara seed (JS) was characterized in approximate composition, crystallinity, thermal profile, morphology, and equilibrium moisture data. Total phenolic content, anthocyanins content, and in vitro antioxidant capacity were assessed for the juçara seedless pomace (JSP). JSP is rich in monomeric anthocyanins (7.19 to 7.23 mg cyanidin 3-O-glycoside/g dry matter [dm]), presents high antioxidant potential, elevated dietary fibers (72.7% dm), considerable amount of lipids (12.8% dm), low protein content, and ash traces. JS is a rich carbon source (76.91% fibers [dm]; 12.21% amylaceous reserve). Being high in carbohydrates, mainly starch, it can be classified as high starch content flour (juçara seed starch-flour [JSS-F]). JSS-F presented B-type crystallinity and conventional starch-like thermal stability. JSS-F exhibited type III sorption isotherm behavior and the Gugghenheim-Anderson-DeBoer model adequately represented the moisture equilibrium data. As a nutritive source of bioactive compounds and starch, juçara pomace should be regarded as a coproduct to be explored as an alternative natural ingredient to food, pharmaceutical, and chemical industries. PRACTICAL APPLICATION: Juçara agroindustrial residues (pomace and seeds) are a promising source of antioxidants and unconventional starch, which are usually discarded after depulping, representing approximately 74% of the fruits. Juçara pomace can be used to produce flour with marketing potential due to their functional properties and nutritional value. This flour can be incorporated directly into formulations or be used in extraction processes to obtain components of interest, for example, anthocyanins, to be used as a natural food dye. Starch can be extracted from juçara seeds, presenting adequate technological properties for partial replacement of conventional starches.

Chemical modification of citrus pectin: Structural, physical and rheologial implications.

The present study aimed to investigate the physical, structural and rheological modifications caused by the chemical modification process of citrus pectin. Therefore, three commercial citrus pectins with different degree of esterification were chemically modified by sequential alkali and acidic hydrolytic process to produce modified citrus pectins (MCP) with special properties. The molar mass (Mw), degree of esterification (DE), monosaccharide composition, 13C NMR spectra, homogeneity, morphology (SEM) and rheological behavior of both native and modified citrus pectins (MCP) were investigated. The chemical modification reduced the acid uronic content (up to 28.3%) and molar mass (up to 29.98%), however, showed little influence on the degree of esterification of native pectins. Modified citrus pectins presented higher amounts of neutral monosaccharides, mainly galactose, arabinose and rhamnose, typical of the Ramnogalacturonana-I (RG-I) region. Rheological tests indicated that the native and modified citrus pectins presented pseudoplastic behavior, however, the MCP samples were less viscous, compared to the native ones. Modified samples presented better dissolution in water and less strong gels, with good stability during oscillatory shearing at 25°C. This study aims to better understand the implications that chemical modifications may impose on the structure of citrus pectins.