D. C. Saxena

Effect of Pretreatments on Drying and Rehydration Kinetics and Color of Sweet Potato Slices

The effect of air temperature and pretreatments (KMS: citric acid) on drying kinetics of sweet potato slices was investigated. Drying experiments were performed in a tray dryer. In falling rate period, moisture transfer from sweet potato slices was described by applying the unsteady-state Fickian diffusion model, and the rate constant (k) were calculated. The effect of temperature on k could be interpreted according to Arrhenius law. Drying rate and therefore k values were found to be affected by pretreatments. Rehydration rates of dried sweet potato slices at 25, 40, 80°C were also determined and found to be independent of drying conditions and rehydration temperature. The ΔE value was found to be the highest for slices treated at 50°C with 0.5:1.0% KMS and citric acid.

Analysis of modes of heat transfer in tandoor oven

Individual modes of heat transfer were estimated for the baking of roti, an Indian traditional product, in a tandoor oven. Mathematical expressions were proposed for the heat adsorbed by and transferred to roti during baking. Heat transfer parameters such as thermal conductivity and emissivity for roties were determined. Conduction and radiation from refractory surfaces were more prominent (51.4 and 44.0%, respectively) than other modes of heat transfer, and conduction contributed more to the product quality aspects when compared to other modes of heat transfer.

Indian Wheat Cultivars: Correlation between Quality of Gluten Proteins, Rheological Characteristics of Dough and Tandoori Roti Quality

Physico-chemical, rheological characteristics and quality of tandoori roti were determined for whole wheat flours from eight commercial wheat cultivars grown at one location. Tandoori roties baked from these flours indicated wide differences in baking performance. Among the varieties, Cpan-3004, GW-180 and K-8804 and WL-1562 were found suitable for the preparation of tandoori roti. These four varieties had higher water absorption capacity (718–735 ml kg-1) when measured in a farinograph at an optimum tandoori dough consistency of 400 BU. The doughs from these varieties also had higher cohesiveness (0·38–0·45) and extensibility (114–121 mm) than other varieties. Total protein, gluten as well as total glutenin (soluble and insoluble) contents were found to be maximum in these four varieties. Varieties having Glu-1 score of 6 were found to be more suitable for roti preparation. The prediction equation derived for correlating total protein and total glutenin in flour with overall sensory score of roti was found highly significant (R2 = 0·92). The results suggest that the medium hard wheats are suitable for the preparation of tandoori roti.

Physical, textural, and sensory characteristics of wheat and amaranth flour blend cookies

Abstract This study examined the effects of whole amaranth substitutions at various proportions and evaluated the cookies baking behavior. Six types of formulations of cookies were prepared with whole amaranth flour ranging from 20, 40, 60, 80, and 100%. These cookies were evaluated for physical (thickness, diameter, spread ratio, and bake loss), textural, and organoleptic attributes. The diameter and spread ratios were found to be higher in whole amaranth flour cookies 52.20 mm and 6.46, respectively, as compared to other blends (20–80%) of cookies from 51.37 to 51.92 mm and 6.13 to 6.36, respectively. Textural measurement showed that hardness of cookies decreased with the addition of amaranth flour. Whole amaranth flour cookies required least snap force (72.4 N) compared to control (whole-wheat flour) cookies (145 N). Sensory data indicated that the amaranth cookies with up to 60% were acceptable, while additional amaranth flour resulted in a decreased mean score for overall acceptability.

Thin layer drying characteristics of sweet potato starch based films and mathematical modelling.

Drying kinetics of sweet potato starch based films was studied at different temperatures (45, 50, 55 and 60°C). Films were prepared by casting technique and were dried in hot air oven. In declining rate period, moisture transfer from films was described by applying the Page’s model, and the rate constant (k) was calculated. Results indicated that removal of moisture from these thin films was fast in initial hours and with increase of temperature as well. The effect of temperature on rate constant (k) was interpreted according to Arrhenius law. The rate constant increased (0.000–0.002 h-1) with the drying air temperature.

Antioxidant activity, total phenolics, flavonoids and antinutritional characteristics of germinated foxtail millet (Setaria italica)

Abstract A central composite rotatable design was applied to analyse the effects of independent variables [soaking time (ST), germination time (Gt) and temperature (GT)] on responses [antioxidant activity (AoxA), total phenolic contents (TPC) and flavonoid contents (TFC)]. The results indicated that with increase in ST, Gt and GT, AoxA, TPC (free/bound) and TFC (free/bound) of foxtail millet increased significantly. The best combination of germination bioprocess variables for producing optimized germinated foxtail millet flour with the highest AoxA (90.5%), TPC (45.67 mg gallic acid equivalent (GAE)/100 g sample) and TFC (30.52–43.96 mg RU/g sample) were found with soaking time of 15.84 min having germination temperature of 25°C. The optimized germinated foxtail millet flour was nutritionally rich as it produced higher protein (14.32 g/100 g), dietary fibre (27.42 g/100 g), calcium (25.62 mg/kg), iron (54.23 mg/kg), magnesium (107.16 mg/kg) and sodium (69.45 mg/kg) per kg as compared to un-germinated foxtail millet flour.

Effect of different baking modes on the physico-chemical and sensory characteristics of tandoori roti

Studies were carried out to determine the effect of baking, in different types of oven such as an earthen tendoor, a gas tandoor, an electric oven and a heated plate, on the physico-chemical and quality characteristics of tandoori roti. The studies indicated that the extent of gelatinization of starch varied depending on the type of oven used and was found to be 74.6, 78.4, 90.7 and 88.4% in roties baked in an earthen tandoor, a gas tandoor, an electric oven and a heated plate respectively. The pasting characteristics of starch, separated from the tandoori roti sample and measured using a Rapid Visco Analyzer, indicated the highest peak viscosity (36 SNU) for tandoori roti baked in an earthen tandoor and the lowest (25 SNU) for that baked in an electric oven. The concentration of high molecular weight proteins was lower in roti baked in an earthen tandoor and a gas tandoor, indicating greater dissociation of high molecular weight proteins during baking in such ovens. The sensory texture, taste and flavour of roti baked in an earthern tandoor was found to be superior to those baked in other types of ovens.

Changes in the GABA and polyphenols contents of foxtail millet on germination and their relationship with in vitro antioxidant activity

Germination along with ultrasonic assisted extraction induced a significant beneficial effect on the characteristics of polyphenolic components profile, GABA contents and in vitro antioxidant capacity of the foxtail millet flour extracts. The total antioxidant activity (29.0-45.23 mgAAE/g) and reducing power (0.53-0.76 µg/ml) increase during germination were due to quantitative increase in phthalicacid; hex-3yl-ester; hexadecanoicacid methylester etc. whereas, increase in DPPH (48.32-59.62%) and hydrogen peroxide scavenging activities (35.44-63.07 mM-Trolox/g) were attributed to increase in hexadecanoic acid methylester; 9,12-Octadecadienoicacid ethylester and synthesis of new compounds like pentadecanoicacid; 14-methyl-methylester etc. The metal chelating abilities (34.92-57.38 mgEDTA/g) and in vitro antioxidant activity increase due to overall increase in phenolics, flavonoids along with GABA contents. Synthesis of additional polyphenolic components viz. astaxanthin, propanoicacid, 1-monolinoleoylglycerol trimethylsilylether, 9,12,15-octadecatrienoicacid etc. as a result of germinated explored the possible potential utilization of germinated foxtail millet grains in various functional and convenience food formulations.

Effect of storage conditions and packaging materials on the quality attributes of gluten-free extrudates and cookies made from germinated chenopodium (Chenopodium album) flour

This study evaluated the effect of storage and packaging materials on the quality attributes of germinated C. album flour extrudates and cookies. For the storage studies of the extrudates low density polyethylene (LDPE) and laminated pouches (LP) of polyester-aluminium-polypropylene (PE-AL-PP) and for cookies LDPE and LP of metalized polyester polyethylene (MET-PPE)were used at ambient temperature (25 ± 2 °C). Quality parameters like moisture content, water activity, free fatty acids, peroxide value, bulk density, color, hardness, microbial and sensory analysis of developed products were evaluated at an interval of 15 days during 4 months of storage period. Higher quality changes were observed in extrudates and cookies packed in LDPE than in LP and MET-PPE. The overall acceptability data showed higher decrease in the sensory scores of extrudates and cookies packed in LDPE (7.9–5.5 for extrudates and 7.75–5 in cookies) as compared to LP (7.9–6.12 for extrudates) and MET-PPE (7.75–6.10 for cookies) packages. From the above study and results, it is suggested that the LP for extrudate and MET-PPE in cookies can be used for their storage upto 4 months at ambient conditions.

Using combined optimization, GC–MS and analytical technique to analyze the germination effect on phenolics, dietary fibers, minerals and GABA contents of Kodo millet (Paspalum scrobiculatum)

A central composite rotatable design was applied to study the effects of soaking time, germination time and temperature on the responses; total phenolics, total flavonoids and antioxidant activity for the biochemical enhancement of bioactive components of Kodo millet. The optimum conditions for producing germinated Kodo millet flour of highest TPC (83.01mgGAE/100g), TFC (87.53mgRUE/g) and AoxA (91.34%), were soaking time (13.81h), germination temperature (38.75°C) and germination time (35.82h). Protein increased significantly form, 6.7 to 7.9%, dietary fibers from 35.30 to 38.34g/100g, minerals from 232.82 to 251.73mg/100g, GABA contents from 9.36 to 47.43mg/100g, whereas phytates and tannins decreased from 1.344 to 0.997mol/kg and 1.603 to 0.234mg/100g respectively, in optimized germinated Kodo millet sample. Six new bioactive compounds [n-propyl-9,12,15-octadecatrienoate (0.86%), pregan,20-one-2hydroxy,5,6,epox-15-methyl (3.45%), hexa-decanoicacid (8.19%), 9,O-ctadecenoicacid (5.00%), butyl-6,9,12,15-octadecatetraenoate (4.03%), hexadecanoicacid-methylester (1.43%)], synthesized as a result of germination under optimum conditions in the Kodo millet depicted the germination potential of millets as a source of valuable bioactive compounds.