Physical modification of starch: changes in glycemic index, starch fractions, physicochemical and functional properties of heat-moisture treated buckwheat starch.

Native buckwheat starch was extracted and modified by heat-moisture treatment (HMT) with different treatment time (15, 30 and 45 min) to investigate its effect on physicochemical, morphological, functional properties, starch profile (rapidly digestible starch, RDS; slowly digestible starch, SDS and resistant starch, RS fractions) and expected glycemic index (eGI). Results revealed that with increasing time duration of HMT from 15 to 45 min, amylose content, pasting temperature and thermostability increased substantially whereas swelling power, solubility and viscosity parameters decreased. The SEM micrographs showed that HMT caused fissures in the granule and surface indentation. HMT-45 (starch treated for 45 min) had the lowest RDS content (29.33%) and the highest SDS (51.30%) and RS (8.21%) levels. The decreased hydrolysis rate, high amylose and RS content of HMT-45 resulted in a significant decrease in estimated glycemic index (eGI) values from 51.49% (Native) to 44.16% (HMT-45) thus indicating its role in prevention of non-insulin- dependent diabetes.

Engineering properties of horse gram (Macrotyloma uniflorum) varieties as a function of moisture content and structure of grain.

The study was conducted to determine the engineering properties of horse gram varieties namely GPM-6, PAYIUR-2, and BHK as a function of moisture content in range of 10-30%. The average length, width, thickness, geometric mean diameter, arithmetic mean diameter, thousand kernel weight, sphericity, porosity and angle of repose ranged from 5.43 to 6.53 mm, 3.96 to 4.48 mm, 2.21 to 2.99 mm, 3.62 to 4.41 mm, 3.86 to 4.64 mm, 30.32 to 49.11 g, 63.56 to 72.66%, 35.20 to 38.76% and 22.72° to 29.86° respectively as the moisture content of the grain increased from 10.08 to 29.98%. The bulk density and true density of the grain decreased from initial range of 810-901 to 734-801 kg m-3 and 1250-1426 to 1168-1308 kg m-3. The volume, porosity and terminal velocity of the grain increased linearly with increase in moisture content. The coefficient of friction also showed positive correlation for all surface materials, the highest increase was found for plywood in all varieties of horse gram seeds. Dehulling properties of the grain found to be significantly affected by the change in moisture content. The overall dehulling ranged from 53.44 to 61.21% for GPM-6 and 55.58 to 61.06% for PAYIUR-2 variety of horse gram. Textural properties of the grains were also found to be significantly affected by the change in moisture content from 10 to 30%. The data generated in this study will be highly useful in optimization of post-harvest processing operations as well as to design and develop related processing equipment for horse gram.

Development and storage stability of buckwheat chips using response surface methodology (RSM).

Processing conditions (potato level, frying temperature and frying time) were optimized for the development of buckwheat based chips using response surface methodology (RSM). Moisture content, oil uptake, color values, hardness and overall acceptability (OAA) were used as indices of product quality. The polynomial regression model was fitted with R2 values of 0.983, 0.982, 0.98, 0.996, 0.973, 0.984 and 0.985 for moisture content, oil uptake, L, a*, b* values, hardness, and OAA respectively indicating fitness of the models. Potato level and frying temperature showed a significant effect on all responses at linear and quadratic levels except frying temperature for OAA at the linear level and hardness at quadratic level. Frying time showed significant effect on a* value, b* value, hardness and OAA at linear level. Interaction between all processing variables had a significant effect on a* value. Interaction between potato level and frying temperature had significant negative effect on moisture content of buckwheat chips. Potato level (30%), frying temperature (169 °C) and frying time (51 s) were found to be the optimum processing conditions with maximum OAA (8.36). 0.33 aw was established as the water activity at which maximum stability of chips was shown. Buckwheat chips packed in both polypropylene (PP) and metallised polyester (MP) remained stable and acceptable for 6 months at RT whereas for 3 and 6 months in PP and MP films respectively at 37 °C.

Studies on the shelf-life enhancement of potato stuffed parotha using thermal processing.

Convenient, ready-to consume thermally processed potato stuffed parothas retaining their natural sensory attributes have been developed. Response Surface Methodology was used to optimize the Stuffing: dough ratio along with other ingredients. Optimized Stuffed parothas were packed in indigenously developed retortable pouches and processed in a steam-air retort. The time-temperature history was recorded during heat processing using an Ellab data cum Fo recorder. The total processing time was 25 min with a Fo value of 3.5. The quality of the developed product was evaluated chemically, sensorily and microbiologically to assess the shelf-life. After 12 months of storage, peroxide value (PV), thiobarbituric acid value (TBA) and free fatty acid value (FFA) increases significantly (p ≤ 0.05) from 9.98 to 29.16 meqO2/Kg fat, 0.101 to 0.171 mg MA/Kg sample and 1.01 to 2.66 % oleic acid respectively. The chemical changes and overall acceptability scores were found to be negatively correlated during storage. Textural and colour values also had an impact on the sensory scores of stuffed parothas during storage. After 12 months of storage, sensory scores decreases significantly (p ≤ 0.05) from 8.6 to 7.1 on a nine point hedonic scale. Microbiologically stuffed parothas remained stable during entire period of storage.

Optimization of process variables for instant preparation of neyyappam like product and extension of shelf-life.

Neyyappam is a very popular traditional sweet of Kerala and Tamilnadu. It is prepared from soaked rice (10-12 h) and had limited shelf-life. Response surface methodology was adopted to optimize, the levels of variables i.e. jaggery, baking powder and holding time based on quantity of rice with selected responses i.e. hardness, bulk density and overall acceptability. All the three variables i.e. jaggery, baking powder and holding time had negative effect (p ≤ 0.05) on hardness at linear level. Bulk density was also negatively affected (p ≤ 0.05) by jaggery and baking powder. However, the overall acceptability was positively affected (p ≤ 0.05) by jaggery and baking powder. It was recommended to use jaggery 90 g/100 g rice flour, baking powder 1.5 g/100 g rice flour and holding time of 13.0 min. Optimized samples were packed in polyethylene pouches, heat treated in a cabinet dryer at 90°C for 2 h, stored under ambient temperature conditions along with control and monitored for peroxide value, free fatty acids and thiobarbutyric acid values as well as microbiological, sensory and textural changes. It was observed that control samples had visible yeast and mould growth at 3rd day, while the treated ones remained highly acceptable up to 30 days with respect to chemical, textural, sensory and microbiological changes.

Development of shelf stable protein rich composite cereal bar.

Protein rich composite cereal bar based on cereal ingredients was prepared using semi automatic tablet making machine, packed in poly propylene (PP), paper aluminium foil polyethylene (PFP), metallised polyester (MP) followed by vacuum packing in metallized polyester films. Proximate composition, mineral contents as well as changes in peroxide value (PV), free fatty acid value (FFA), thiobarbituric acid value (TBA), browning, fatty acid profile, vitamins, effect of water activity on lipid peroxidation, fortification with vitamins and minerals, microbiological as well as sensory parameters during storage under ambient (15-34°C) and 37°C temperature conditions were studied. Composite cereal bar remained shelf stable for 3 months in PP and 6 months in PFP, MP and MP plus vacuum packing under ambient and 37°C temperature conditions.