Impact of spray drying conditions on the reconstitution, efficiency and flow properties of spray dried apple powder-optimization, sensorial and rheological assessment.

Spray drying is a preferred choice for development of highly soluble, rapidly dispersible apple powder. However, adhesion during spray drying of syrups and juices is encountered which leads to product loss. The main solution to reduce adhesion is using drying aids. Besides, control of spray drying operating parameters (inlet air temperature and feed flow rate) also closely govern the powder yield, physical, functional and microstructural properties of spray dried fruit powder. Thus, the aim of the study was to evaluate the effect of inlet air temperature (IAT), carrier agent concentration (MD:GA), feed flow rate (FFR) & feed TSS (FTSS) on moisture content, hygroscopicity, dispersibility, water solubility index (WSI), bulk density (BD), porosity (Φ), flowability, lightness (L*) and radical scavenging activity (RSA). Design expert predicted IAT of 160 °C, MD and GA concentration of 14% and 6% respectively, FFR of 350 rpm & FTSS of 15oBrix as optimum condition for development of easily dispersible, highly soluble and least hygroscopic powder. The powder developed after following the optimized condition (SDAP) recorded moisture content as 2.91%, hygroscopicity as 25.29%, dispersibility as 92.50%, WSI as 94.17%, bulk density as 314.1 kg/m3, porosity as 57.19, flowability as 25.83°, L* value as 70.54 and RSA as 14.37. Among different powder reconstitution concentrations, 25% w/v concentration came out to be the best for reconstitution on the basis of sensory evaluation and rheological test. Frequency sweep test for all the reconstituted juice samples showed higher storage modulus than loss modulus for all the applied frequencies. The results of the study conferred that the developed powder could be used for commercial purpose.

Preparation of a biodegradable chitosan packaging film based on zinc oxide, calcium chloride, nano clay and poly ethylene glycol incorporated with thyme oil for shelf-life prolongation of sweet cherry.

This study includes development of chitosan-based films with incorporated essential thyme oil and different combinations of cross-linkers viz., ZnO, CaCl2, NC, and PEG for the safe storage of sweet cherries. The resulting films stored with sweet cherries were analyzed for different physicochemical and antimicrobial properties. Incorporation of ZnO, CaCl2, NC, and PEG in chitosan-based films maintained fruit quality by conserving higher total soluble solids, titratable acidity, and reduced weight loss. The combined ZnO + CaCl2 + NC + PEG in chitosan-based films also suppressed microbial activity. The sensorial quality of fruits stored with CH + ZnO + CaCl2 + NC + PEG treatment was also stable during storage. In conclusion, the combined CH + ZnO + CaCl2 + NC + PEG with added thyme oil application is an effective approach to maintain the postharvest quality and could be an alternative to increase the shelf life of sweet cherries, besides decreasing environmental impacts of non-biodegradable packages.

Development of low glycemic index instant Phirni (pudding) mix-its visco-thermal, morphological and rheological characterization.

High amylose rice (HAR) and carboxymethyl cellulose (CMC) are the preferred choices for enhancement of resistant starch content and lowering of glycemic index in dairy desserts. The effects of different levels of skimmed milk powder (SMP): HAR flour (45:55 to 75:25) and CMC (0.1 to 1%) were investigated on physical characteristics of dry-mix and on texture profile parameters, resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL) and overall acceptability of phirni (a traditional milk pudding). Design expert predicted SMP (70): HAR (30) and CMC (0.8%) as optimum levels for reducing the pGI and maximizing the RS content and other quality characteristics in phirni. RS content of phirni (4.38%) prepared from optimized dry-mix (ODM) was higher while pGI (48.12) and GL (7.50) were lower as compared to phirni prepared from market dry-mix (MDM). The visco-thermal properties of ODM and MDM also showed significant variations. Storage modulus (G') and loss modulus (G'') indicated that ODM phirni was less solid than MDM phirni. Scanning electron micrographs showed fused structures in ODM, while coarse sheet like structures were observed across the surface of MDM. Thus, ODM can be a promising substitute for the available milk desserts for diabetic patients.

Visco-thermal and structural characterization of water chestnut flour.

In order to increase flour recovery, resistant starch content and to lower the glycemic index and glycemic load, the water chestnuts were subjected to pre-optimized conditions of pre-conditioning. The low glycemic index water chestnut flour (F1) obtained thereafter was analyzed for different functional, viscous, thermal and structural properties. F1 exhibited improved functional properties due to gelatinization of starch followed by retrogradation during pre-conditioning which confirms its feasibility for development of diverse food products in comparison to commercially available market flour (F2). Pasting properties-peak viscosity, hold viscosity, breakdown viscosity, final viscosity and set back viscosity (SBV) were found significantly (p < 0.01) higher in case of F1 than F2. Higher peak viscosity of F1 can be accorded to its higher swelling capacity than F2. Further, higher SBV of F1 suggests its susceptibility towards retrogradation and gel formation. Differential scanning calorimetry results revealed that gelatinization temperature, endothermic peak width, onset, peak and conclusion temperatures were significantly (p < 0.01) lower, whereas enthalpy of gelatinization and peak height index were significantly (p < 0.01) higher in case of F1 as compared to F2. Lower gelatinization transition temperatures of F1 could be attributed to its more water absorption ability than F2 which suggests its potential as a thickening agent in foods. ATR-FTIR studies revealed high absorbance ratio at 1047/1022 cm-1 in F1 as compared to F2 which confirmed the presence of packed double helices within the starch crystalline regions in F1 sample. Scanning electron microscopy showed the smooth, plumper and fused granules in F1 whereas disintegrated granules were observed in F2.

Influence of defatted soy flour addition on the quality and stability of pretzel type product.

Effect of soya flour addition to 70% extraction bread wheat flour (PBW-343) at (0, 5, 10, 20 & 30%) was investigated for physico-chemical, dough handling and pretzel making properties. Results revealed that with increasing DSF addition, farinogram characteristics; water absorption, arrival time, dough development time and dough stability increased while mixing tolerance index and degree of softening decreased. Amylogram characteristics gelatinization temperature, peak viscosity, peak temperature and viscosity at 95 °C decreased with extended rate of DSF addition. Pretzels developed with different levels of DSF addition observed decrease in moisture, fat, non reducing sugars and starch where as ash, protein, reducing and total sugars increased compared to control. Calories calculated from proximate composition showed lower values than control due to high protein and low fat soy flour addition. Minerals increased significantly with increased levels of defatted soy flour addition. Organoleptic evaluation revealed that 5% level of soy flour blended pretzels were found best with respect to texture, colour and flavor on the basis of mean acceptability scores. Pretzels recorded shelf life of 90 days in laminated pouches irrespective of the level of DSF addition.