碩士 / 國立屏東科技大學 / 食品科學系 / 89 / Edible films, due to its high environmental appeals, possess a great potential in replacing traditional petrochemical plastic films for food packaging and storage. It greatly contributes to reducing environmental pollution, as well as conserves the resources. Edible film enhances the anti-microbiological capability, serves as nutritional supplements, and improves the mechanical properties and processibility of foods. This study consists of two parts：investigations on the edible film formulation; and the observation of coating effects on garlic. Microstructure of surface, solid-liquid contact angle, and surface adhesion were elucidated to predict the film forming properties.
Scanning electron micrograph (SEM) results showed no surface rupture either on garlic skin or garlic kernel by sodium alginate solutions. It also indicated tubular texture for the surface of garlic skin, and sponge-like structure for the surface of garlic kernel, respectively. Average surface roughness by magnetic force microscopy (MFM) were under 57 [nm] for garlic skin, and under 13[nm] for garlic kernel, respectively. Through the
contact angle measurements of various formulations of sodium alginate solution, it was revealed that all solutions resulted in low contact angle on the garlic skin surface, indicating stronger solid-liquid interaction of the interface. This was consistent with the results from SEM and MFM, with the conclusion of higher surface roughness for garlic skin.
No significant difference was found for the liquid surface tension among the formulations prepared. Adopting 6 standard liquids surface tension values and their corresponding contact angles on top of garlic skin and garlic kernel, solid surface tension were derived as 46 and 34 [mN/m] for garlic skin and garlic kernel, respectively. Surface index of hydrophilicity were 52 and 43 [mN/m] for garlic skin and garlic kernel, respectively. Higher values of solid surface tension along with higher surface index of hydrophilicity, agreed well with the phenomena of rougher surface topography and higher solid-liquid interaction.
On the subject of mechanical properties, addition of glycerin or palmitic acid resulted in the decrease of water vapor permeability for the formed edible films. The value was 28 [g-mm/kPa-m2-day] for pure sodium alginate film, compared 20 [g-mm/kPa-m2-day]
for 0.5% addition of glycerin, and 19 [g-mm/kPa-m2-day] for 0.5%
addition of palmitic acid. Glycerin also resulted in the decrease of tensile strength yet to increase the elongation percentage at break. Palmitic acid seemed to decrease the elongation percentage, although no conclusive results were found on tensile strength.
Preliminary results showed the possibility of tools in the research fields of edible coating. Assessment of interaction between edible film and coated objects was also elucidated through the study of surface topography and contact angle measurements.
| Identifer | oai:union.ndltd.org:TW/089NPUST253009 |
| Date | January 2001 |
| Creators | Whitney Chen, 陳惠琳 |
| Contributors | C.C. Liu, Y.K. Guu, 劉展冏, 古源光 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 108 |
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