Search

Abstract: The antimicrobial and antioxidant potential of zein and zein–wax composite films having different release profiles for lysozyme and mixture of lysozyme, catechin and gallic acid were tested on cold-stored fresh Kashar cheese inoculated with Listeria monocytogenes ATCC 7644. All lysozyme containing films prevented the increase of L. monocytogenes counts in Kashar cheese for 8weeks at 4°C, but it was only the zein–wax composite films with sustained lysozyme-release rates which caused a significant reduction (−0.4 decimals) in initial microbial load of inoculated cheese samples. The mixture of catechin and gallic acid improved the in vitro antimicrobial effect of films against L. monocytogenes, but showed no considerable antimicrobial effect in cheese. However, the films containing catechin and gallic acid were effective in preventing oxidative changes in cheese. This study showed the possibility of increasing safety and quality of fresh cheeses by use of active packaging employing natural antimicrobial compounds and controlled release technology. Industrial relevance: There has been a growing interest to develop the functional properties of packaging materials and to obtain packed foods with better shelf-life and quality. Active packaging incorporating antimicrobials is one of the most promising areas since application of this method can improve safety of foods by inhibiting pathogenic bacteria or controlling spoilage flora by using minimum amounts of active compounds. Recently, health concerns of consumers and environmental problems related to plastics increased the popularity of using natural antimicrobial substances in edible films and coatings. This work employs a GRAS status natural antimicrobial lysozyme and zein a major by-product of rapidly growing oil and bioethanol industries which can form self-standing films, coatings or casings. The results of this study showed the possibility of using flexible antimicrobial and antioxidant films with controlled release properties in diary industry. [Copyright &y& Elsevier]

Abstract: The aim of this study was controlled release of lysozyme by modification of hydrophobicity and morphology of zein films using composite and blend film making methods. The incorporation of beeswax, carnauba or candelilla wax into films at 5% (w/w) of zein gave composite films containing amorphous wax particles, while incorporation of oleic acid into film at 5% of zein caused formation of blend films containing many spherical zein capsules within their matrix. The lysozyme release rates of composites reduced as the melting point of waxes increased. The composites and blends showed 2.5 to 17 fold lower lysozyme release rates than controls. The films were effectively plasticized by using catechin. The catechin also provided antioxidant activity of films (up to 69μmol Trolox/cm2) and contributed to their controlled release properties by reducing film porosity. The films showed antimicrobial activity against Listeria innocua. This work showed the possibility of obtaining advanced edible films having flexibility, antimicrobial and antioxidant activity and controlled release properties. [Copyright &y& Elsevier]

Abstract: To eliminate their classical brittleness and flexibility problems zein films were plasticized by incorporation of different phenolic acids (gallic acid (GA), p-hydroxy benzoic acid (HBA) or ferulic acids (FA)) or flavonoids (catechin (CAT), flavone (FLA) or quercetin (QU)). The use of GA, CAT, FA and HBA at 3mg/cm2 eliminated the brittleness of films and gave highly flexible films showing elongations between 135% and 189%, while FLA and QU caused no considerable effect on film elongation. The films containing FA and HBA showed extreme swelling and lost their structural integrity when hydrated in distilled water. In contrast, CAT and GA containing films maintained their integrity following hydration. Most of the GA (up to 93%) and a considerable portion of CAT (up to 60%) in the films existed in soluble form. Therefore, the films showed antioxidant and/or antimicrobial activity. The TEACs of soluble phenolic compounds in 3mg/cm2 CAT and GA containing films were 21.0 and 86.2μmoltrolox/cm2, respectively. The GA containing films showed antimicrobial activity on Listeria monocytogenes and Campylobacter jejuni, while CAT showed no antimicrobial activity on these bacteria at the studied concentration. This work opens a new perspective for using zein in flexible bioactive packaging. [Copyright &y& Elsevier]

Abstract: This study investigated the effects of controlled pepsin hydrolysis on antioxidant potential and fractional changes of chickpea protein extracts (CPE). The enzyme hydrolysis increased soluble protein content (1.2 to 2-fold) and free radical scavenging activity (1.9 to 3-fold) of hydrolyzed chickpea protein extract (HCPE), but almost unaffected its antioxidant potential in oil-in-water emulsion system and reduced its iron chelating capacity (1.3-fold) and functional properties. The chromatographic fractions of CPE are mainly acidic, while those of HCPE are mainly basic and neutral. The majority of chickpea proteins had pI between 4.5 and 5.5, and molecular weight (MW) between 15 and 40kDa, while MW of their pepsin hydrolysis products ranged between 6.5 and 14.2kDa. The main antioxidant proteins in CPE and HCPE fractionated by ultrafiltration had MW greater than 30kDa and between 2 and 10kDa, respectively. The chickpea proteins and hydrolysates showed different potentials as functional food ingredients. [Copyright &y& Elsevier]

Abstract: In this study, antioxidant activities of water-soluble protein extracts from chickpeas and white beans were investigated. The area under the curve (AUC) values of lyophilized crude protein extracts (dialyzed or undialyzed) from thermally processed (121°C for 20min) or heat-treated (90°C for 20min) chickpeas (73–91μmol trolox/g) and white beans (39–67μmol trolox/g) indicated a higher free radical-scavenging capacity and thermostability for chickpea proteins than for white bean proteins. The thermal processing also increased the Fe+2-chelating capacity of lyophilized chickpea crude protein extracts 1.8-fold whereas it caused a 2.3-fold reduction in the Fe+2-chelating capacity of lyophilized white bean crude protein extracts. Dialysis increased the protein content of lyophilized chickpea extracts 1.5–2-fold but it did not affect the protein content of lyophilized white bean extracts significantly. Ammonium sulfate precipitation was not effective for selective precipitation of antioxidant proteins. However, it improved the free radical-scavenging capacity of lyophilized protein extracts from thermally processed chickpeas and white beans by almost 25% and 100%, respectively. DEAE-cellulose chromatography, indicated the presence of five (A1–A5) and three (B1–B3) antioxidant protein fractions in heat-treated and thermally processed chickpea protein extracts, respectively, and can be used for the partial purification of antioxidant proteins. The results of this study showed the good potential of chickpea proteins as thermostable natural food antioxidants. [Copyright &y& Elsevier]