Research And Application On Edible Film's Forming Property Made By Mixture Of Hsian-taso Gum And Carrageenan

Hsian-tsao(Mesona procumbens Hemsl.), called Eone Chinensis or Mesona Blumes, is an annual herbaceous plant of Labiatae. Hsian-tsao gum extracted from the Stem and leaf of Hsian-tsao have good performance of natural hydrocolloids. Different decoloring methods was applied to hsian-tsao gum extraction, and preparation and characterization of hsian-taso gum/carrageenan film was analyzed. Futhermore, the antimicrobial activity was experimented, and effect of edible hsian-taso gum/carrageenan coating as carrier of nisin and natamycin on shelf life of loquat was also investigated. Therefore an effective utilization way for the use of Hsian-tsao was offered, a theoretical basis for the applications of natural hydrocolloids in food field was also provided.1. Three different decoloring methods, including activated carbon, resin and ultrafiltration, were compared to determine the most optimum method and condition. The best result was obtained when activated carbon dosage was 2.5%, decolorization temperature was 60℃and decolorization time was 50min, under which the decolorizing rate reached 92.3% and polysaccharide loss rate was 20.5%; The D301 resin used to decolorize hsian-tsao gum was selected from five types of ion exchange resins and macroporous absorption resin. The best result for decolorizing hsian-tsao gum was determined as follows: the volumn of resin was 3%, decolorization time was 3h(130r/min), decolorization temperature was 50℃and pH was 5.0, under which the decolorizing rate reached 95.5% and polysaccharide loss rate was 15.5%; the pigment substance would remove efficiently from hsian-tsao gum by 10000Da molecular weight cut-off PES, under which the decolorizing rate reached 85.4% and polysaccharide loss rate was 20.4%. Through the research of the process conditions on decolorizing, the D301 resin possessed higher decolorizing rate and lower polysaccharide loss rate. It was indicated that the D301 resin was the best technology for the decoloration of hsian-tsao gum.2. Effects of different factors on the properties of hsian-tsao gum/carrageenan film were studied. Based on the indices of puncture strength, tensile strength, elongation at break and water vapour permeability, the uniform orthogonal designs method was conducted by selecting four factors such as total solid(1.5%, 2.0%, 2.5%), different ratio(10/90, 20/80, 30/70), sucrose ester(0.1%, 0.2%, 0.3%) and drying temperature(40℃, 50℃, 60℃), and the principal component geometric mean analysis method was adopted to carry out multi-index analysis of the edible film according to the factors and levels. The best result was obtained when total solid was 1.6%, ratio of hsian-tsao gum and carrageenan was 20/80, sucrose ester was 0.1%, drying temperature was 52℃, glycerol content was 1.5% and pH was 7, under which hsian-tsao gum/carrageenan film is of good comprehensive property.3. The antimicrobial properties of nisin and natamycin supported in decolorized hsian-tsao gum/carrageenan film was tested, and then applied to loquat storeage. The results showed that edible coating made by mixture of hsian-taso gum and carrageenan had significant inhibitory effects on bacteria such as Staphylococcus aureus, Listeria monocytogenes and mould such as Penicillium, Rhizopus when the addition of Nisin was 200mg/L, natamycin was 20mg/L. The results showed that edible coating with antimicrobial agents could significantly inhibit the physiological metabolism of loquat, and decrease nutrient loss. Thus, edible coating made by mixture of hsian-tsao gum/carrageenan could get the best performance for room temperature preservation of loquat.