The evaluation of the physicochemical and thermal properties of garlic powder dried under freeze and cabinet drying
2014
Bayat, Fariba | Saedi,Hamid | Shaabanian, Mohammad | Badii, Fojan
Chemical and thermal properties of powders were used for determining stability and suitable conservation parameters like temperature and relative humidity. For this reason, garlic slices with 2 mm thickness were dehydrated using two methods, includings freez and cabinet dryings. Apparent density, color, total and reducing sugars, protein, fat, fiber and total and nonenzymic pyruvate of powders were measured for both methods. Garlic powders were treated for seven days at the temperature of 25±2 ΊC and the relative humidity of 0, 11, 22, 33, 40, 55, 77 and 95 %. The glass transition temperature and specific heat capacity were measured precisely. Results showed that at freez dried powder, density and the loss of pyruvate and color changes was less than the other powder. Isotherm curves until relative humidity of 40 % were relatively constant and at they increased at higher relative humidity the moisture content of treated powders. The moisture sorption isotherm curves for both powders were similar and showed minor differences. The value of glass transition temperature of freez dried powder with 50.36 ΊC was more than cabinet dried powder with 44.5 ΊC. The glass transition temperatures of powders decreased with increasing moisture content of them. Heat capacity of powders increased with increasing the glass transition temperatures. The value of critical condition for garlic powder storage estimated on the relative humidity higher than 55 % and temperatures higher than 35 ΊC that increased the risk of moisture absorption and adhesive.
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