Glass Transition and Sticky Point Temperatures and Stability/Mobility Diagram of Fruit Powders

Abstract

Principal components present in fruits are low molecular weight sugars and some organic acids. They have low glass transition temperature (T g ) and are very hygroscopic in their amorphous state, so the dry product becomes sticky. Water acts as a plasticizer and decreases the glass transition temperature of the product with the increase in moisture content and water activity. To overcome this problem, ingredients having high T g value, such as maltodextrin, and food grade anti-caking agents were added to prepare vacuum dried fruit powders. The relationship between T g and a w provides a simple method for prediction of safe storage temperature at different relative humidities environment. Food powders namely, mango, pineapple, and tomato (3-4% w.b moisture content) were produced by mixing with maltodextrin and tri calcium phosphate at predetermined levels before drying. The relationship among glass transition temperature (T g ), sticky point temperature (T s ), moisture content and water activity of the three powders was represented in a stability/mobility diagram to find out safe storage conditions. Glass transition temperature of the fruit powders were interpreted in terms of the Gordon-Taylor model for verification. Glass transition and sticky point temperatures were compared by plotting them in a graph against moisture content.

Obtaining orange juice–maltodextrin powders without structure collapse based on the glass transition temperature and degree of polymerization

“…Carbohydrates such as sucrose, fructose and glucose typically present a T g value in the range of 5-68°C (Jaya & Das, 2009). This wide T g range may induce changes in the initial state of the powders subjected to drying processes such as spray drying (Shrestha, Ua-Arak, Adhikari, Howes, & Bhandari, 2007).…”

Measurement and Comparison of Glass Transition and Sticky Point Temperatures of Distillers Dried Grains with Solubles (DDGS) with Varying Condensed Distillers Solubles (CDS) and Drying Temperature Levels

“…closely related. Jaya and Das (2007) also showed correlation between T g and T s values, indicating that T s and T g are both similar parameters with different experimental techniques to measure them. According to Ozmen and Langrish (2006), in skim milk powder T g and T s were highly correlated, and they are virtually the same measurement with different experimental approaches.…”

“…Previous research on T g with various food and fruit powders predicted the T g for varying moisture contents, but there have been no studies done (prior to this paper) that examined DDGS, specifically the effects of drying temperature, CDS, and moisture content factors on the Gordon-Taylor (1952) Jaya and Das (2007) was able to construct a power law type of equation for predicted K parameter, but there was only moisture content as the independent variable, unlike our research design. Similar to this study, Sablani et al (2007) was able to calculate predicted K and T g values for different types of salt with low moisture contents by using the Gordon-Taylor model (1952).…”

“…However, the traditional setup (Lazar et al 1956) and procedure of measuring T s were modified several times by several authors (Pasley et al 1995;Hennigs et al 2001;Chegini and Ghobadian 2007). There are peer-reviewed articles comparing T g with T s and elaborately describing the phenomenon of stickiness or caking in food powders (Downton et al 1982;Chuy and Labuza 1994;Jaya and Das 2007).…”

“…For more details on how to calculate X s and X w for given binary system (water/solid), refer to Gordon and Taylor (1952). The K parameter, which is dependent on the X w , is different for individual materials and must be determined through regression analysis (Jaya and Das 2007).…”