Glass Transition Temperature Of Powder Research Articles

The optimization of spray-drying process for the development of apricot powder using response surface methodology

PurposeApricots are not only nutritionally-rich but also possess pharmacological significance owing to their high antioxidant activity, and they are rich in vitamins, fibers, bioactive phytochemicals and minerals. Because of its immense organoleptic characteristics, apricot juice (AJ) is well accepted; however, it has a limited shelf-life, thereby demanding it to be converted into other shelf-stable form. One of the approaches is converting this juice into dehydrated powder. Amongst the various dehydration techniques available, spray drying is usually preferred; however, it involves the use of several independent variables, which need to be optimized, thus prompting to optimize the process to obtain spray dried apricot powder (SDAP) with improved quality.Design/methodology/approachThe spray-drying process of apricot juice was done using the response surface approach. The process variables included the inlet air temperature of 135–220°C, gum arabic concentration of 4–25%, feed flow rate of 124–730 mL/h, feed total soluble solids (TSS) of 10-30°Brix and atomization speed of 11,400–28,000 rpm. The dependent responses were powder yield, hygroscopicity, solubility, moisture content, carotenoids (CT), ascorbic acid (AA), radical scavenging activity (RSA), lightness, wettability, bulk density, particle density and porosity.FindingsAmongst all independent variables, inlet air temperature had most predominant impact on all the investigated responses. The optimum processing conditions for development of apricot powder with optimum quality were 190°C inlet air temperature, 18.99% gum arabic, 300.05 mL/h feed flow rate, 24°Brix feed TSS and 17433.41 rpm atomization speed. The experimental values were found to be in agreement with the predicted values, indicating the suitability of models in predicting optimizing responses of apricot powder. Flowability as Carr's index (CI) (22.36 ± 1.01%) suggests fair flow of powder. Glass transition temperature of powder was 57.85 ± 2.03°C, which is much higher than that of ambient, suggesting its better shelf stability.Originality/valueTo the best of author's knowledge, very limited or very few studies have been carried out on the spray-drying process for the manufacture of SDAP. The results of this investigation will open up new horizons in the field of food industry in the Union Territory of Jammu and Kashmir, India or elsewhere in the apricot-growing areas of India.

A Method for Estimating Glass Transition Temperature of Powders by Discoloration of Betanin under Temperature-programmed Heating Conditions

A Method for Estimating Glass Transition Temperature of Powders by Discoloration of Betanin under Temperature-programmed Heating Conditions

Effect of Slurry Concentration and Inlet Temperature Towards Glass Temperature of Spray Dried Pineapple Powder

Spray drying of fruit juices represents another alternative way to improve the physicochemical stability and increase their shelf life. Samples of pineapple powder was produced using the spray drying method to investigate the effect of inlet temperature and slurry concentrations towards the glass transition temperature of the pineapple powder. The spray dryer model used was a laboratory scale dryer and samples were run at different inlet temperatures of 130˚C, 140˚C, and 150˚C. Maltodextrin was used as a carrier agent at different concentrations of 15%, 20%, and 25% (wt/wt). The resulting powders were then analysed for glass transition temperature, moisture content, pigmentation, pH value, and particle morphology. Results showed that at higher inlet temperatures and increment of maltodextrin content, the moisture content of pineapple powder decreased. The glass transition temperature of the powders increased as the inlet drying temperature increased. A similar trend in the glass transition temperature was also observed with the addition of maltodextrin concentration. The pH value of the pineapple fruit juice increased with addition of maltodextrin, the same trend was also observed in the reconstituted pineapple juice. The particle size of the pineapple powders decreased with increasing maltodextrin content and at higher inlet temperatures. The highest yield of powder was produced at spray drying conditions of 130˚C with a maltodextrin content of 25%. The pineapple juice with high ratio of water obtained low glass temperature. Furthermore, the result also shows that the higher amount of pineapple juice and maltodextrin increase had produced more pineapple powder. From the studies it is shows that the best processing condition to obtain a free flowing and least hygroscopic pineapple powder is the sample of 900g of pineapple juice used with 200g of water with the present of 25% maltodextrin.

Physical stability of infant milk formula made with selectively hydrolysed whey proteins

A whey protein ingredient, in which β-lactoglobulin was selectivity hydrolysed, was evaluated during manufacturing of infant formulae. Three model infant milk formula (IMF) powders were produced containing: non-hydrolysed (NH) proteins (60:40; whey proteins:caseins); partially hydrolysed (PH) caseins and whey proteins; and selectively hydrolysed (SH) whey proteins. After homogenisation, particle size (D[4,3]) of the SH formulae was similar (P > 0.05) to NH formulae and was significantly (P < 0.05) smaller than PH formulae. Prior to spray drying (∼55% w/w), the viscosity of SH formulae (14.8 ± 0.3 mPa s) was significantly lower (P < 0.05) than that of the NH (48.6 ± 0.8 mPa s) or PH formulae (27.6 ± 1.5 mPa s). Surface free fat, wettability and glass transition temperature of powders were not significantly (P > 0.05) different. IMF manufactured with SH ingredients have applications in high dry matter processes with potential for reduced energy costs in spray drying.

The use of moisture sorption isotherms and glass transition temperature to assess the stability of powdered baby formulas

The influence of adverse conditions of environment in the case of baby formulas, which are multiple mixtures, should be minimised. Water activity (a w) and moisture content, correlated through sorption isotherms, and glass transition temperature have been considered relevant parameters to describe food stability. The aim of the study was to analyse water activity and glass transition temperature as the function of water content for samples of baby formulas. Three types of baby formulas (mixture, agglomerate, coated agglomerate) were determined by sorption isotherms, DSC and MDSC. DSC curves of mixture, agglomerate and coated agglomerate did not show differences in shape and course. The glass transition temperature of powders stored at different water activities was measured and it decreased with the increase in moisture content, confirming the strong plasticising effect of water on this property. Critical water activities varied from 0.14 to 0.68 and critical moisture contents varied from 0.032 to 0.062 g g−1 powder.

Effect of relative humidity on the store stability of spray-dried beta-carotene nanoemulsions

In order to overcome the limitations of liquid-base emulsion system, beta-carotene nanoemulsions stabilized by modified starch were spray-dried to powders after the emulsification process. The powders showed a good dissolution in water and the reconstituted emulsions had similar particle sizes with the fresh nanoemulsions. A 30 days storage test was carried out to investigate the effect of relative humility (RH) on the storage stability of beta-carotene powders at 25.0 °C. The beta-carotene degradation profiles over time were found to fit well with a Weibull model and also closely related to the film property of the matrix, moisture sorption property and glass transition temperature of the powder. The results showed that modified starches with lower film oxygen permeability had a higher retention of beta-carotene during storage. The glass transition temperature of powder in different RH also affected the rate of beta-carotene degradation. Overall these results provide useful information for choosing wall materials and storage conditions to protect nutraceuticals in delivery systems.