RESUMO
A blend of cassava starch (CS), carboxymethyl cellulose (CMC), and paraffin was prepared as a coating material to maintain the quality of eggs during 4 wk of storage at different temperatures. The efficacy of the CS/CMC/paraffin (6/1/0.5% w/v) coating was investigated in terms of the Haugh unit (HU), weight loss, pH, and microbial load at the end of storage. The best egg storage temperature was 4°C, which maintained an HU of grade AA in coated and uncoated eggs for 4 wk. Lower weight loss (2.14%) was observed in coated eggs at 4°C storage than at 30°C storage (3.26%). The pH in the albumen of coated and uncoated eggs at 4°C increased from 6.84 to 6.88 and 7.01 to 7.03, respectively, after 4 wk of storage. No microbes were detected in the coated and uncoated eggs at 4°C. The maximum microbial count was 728 ± 35 cfu/mL in uncoated eggs at 30°C storage. Egg coating prevented microbial contamination of eggs stored at 30°C for 4 wk. The freshness of the eggs did not affect the nutrient content. The egg-coating material effectively maintained egg quality, prevented microbial contamination of eggs, and increased the shelf life of eggs at storage temperatures of 25 and 30°C.
Assuntos
Manihot , Parafina , Animais , Carboximetilcelulose Sódica , Galinhas , Amido , TemperaturaRESUMO
An egg-coating material was developed to extend the shelf-life and freshness of eggs by blending cassava starch (CS) with gelling agents and waxes. The effects of the properties of this egg coating on egg quality were investigated. Hydroxypropyl methylcellulose (HPMC), carboxymethyl cellulose (CMC), beeswax, and paraffin wax were used. CS blended with low-molecular-weight paraffin (Paraffin(L)) and CMC coating material displayed a tensile strength of 4 MPa, 34% elongation at break, 0.0039 g day-1 m-2 water vapor permeability, and a water contact angle of 89° at 3 min. Eggs coated with CS/CMC/Paraffin(L) solutions had a Haugh unit value of 72 (AA grade) and exhibited a weight loss of 2.4% in 4 weeks. CMC improved the compatibility of CS and Paraffin(L). This improvement and the hydrophobicity of Paraffin(L) provided suitable mechanical and water-resistance properties to the coating material that helped to maintain the quality of the coated AA-grade eggs with low weight loss for 4 weeks.
RESUMO
Oil resistant thermoplastic elastomers (TPE) were prepared using mung bean thermoplastic starch (MTPS) blending with rubbers and sericin. Sericin was incorporated into MTPS as a compatibilizer. MTPS with sericin (MTPSS) was blended with natural rubber (NR) and epoxidized NR (ENR). Sericin at 5% improved the tensile strength (10 MPa), elastic recovery (52%) and morphology of the MTPSS/ENR blend. The mechanical properties, elastic recovery and morphology of the MTPSS5/NR blend were improved by the addition of ENR. The MTPSS/ENR showed palm (28%) and motor oils (8%) swelling resistance because of the hydrophilicity of MTPS and high polarity of ENR. The MTPSS/ENR/NR showed gasoline swelling resistance (104%) because of the hydrophilicity of MTPS and low polarity of NR. FTIR confirmed a reaction between the -NH groups of sericin and the epoxy groups of ENR. This reaction improved the compatibility, mechanical properties, elastic recovery, morphology and oils swelling resistance of the blends.
Assuntos
Elastômeros/química , Óleos/efeitos adversos , Plásticos/química , Fenômenos Bioquímicos , Compostos de Epóxi/química , Óleos/química , Borracha/química , Amido/química , Temperatura , Resistência à Tração/efeitos dos fármacosRESUMO
Thermoplastic elastomer (TPE) was developed by blending thermoplastic starch (TPS) with rubber. Thermoplastic starch-chitosan (TPSC) was prepared by the solution mixing of cassava starch, chitosan (CTS) and glycerol in acidified water (lactic acid 1 wt%) at 80 °C follow by melt mixing at 130 °C. Sodium benzoate (BEN) and chlorhexidine gluconate (Cl) were added during the solution mixing as additives for antimicrobial properties. TPSC was melt-mixed with epoxidized natural rubber (ENR) (70/30 wt/wt). The tensile strength and elongation at break of the TPSC/ENR increased with the additive content. Elastic recovery was improved by the addition of Cl. A new peak in the FTIR data confirmed the reaction between the reactive functional groups of the CTS and the additives with the epoxy groups of ENR. These reactions and miscibility of the TPSC/ENR/additives blends improved the mechanical properties, elasticity, morphology, and antimicrobial properties of the blends.
Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/química , Antifúngicos/química , Quitosana/química , Quitosana/farmacologia , Clorexidina/análogos & derivados , Clorexidina/química , Clorexidina/farmacologia , Elastômeros/química , Elastômeros/farmacologia , Compostos de Epóxi/química , Compostos de Epóxi/farmacologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Tamanho da Partícula , Benzoato de Sódio/química , Benzoato de Sódio/farmacologia , Amido/química , Amido/farmacologia , Propriedades de Superfície , TemperaturaRESUMO
Thermoplastic starch (TPS) was prepared by melt-mixing cassava starch with glycerol. Polyethylene (PE), polyethylene-grafted-maleic anhydride (PE-MAH) and poly(lactic acid) (PLA) solutions at 2% (w/v) were used to coat TPS using the dip coating process. The tensile strength of TPS increased with the dip coating solution technique, especially for PLA coating. Swelling index, water-soluble matter and water droplet contact angle confirmed the water resistant improvement of TPS by PE-MAH and the PLA dip coating solution. Plasticizer bleeding was found in uncoated TPS after storage, but not in the coated TPS. Coating TPS with PE-MAH and PLA improved the tensile properties, water resistance and conquered plasticizer bleeding problems in TPS.