Navdeep Singh Sodhi

Morphological, thermal and rheological properties of starches from different botanical sources

Corn, rice, wheat and potato are the main sources of starches which differ significantly in composition, morphology, thermal, rheological and retrogradation properties. Cereal starches contain a significant quantity of phospholipids, while potato starch is rich in esterified phosphorus. Potato starch exhibits higher swelling power, solubility, paste clarity and viscosity than wheat, rice or corn starches. Morphological characteristics, such as shape and size of the starch granules, exhibit significant differences. Potato starch granules are smooth–surfaced, oval and irregular or cuboidal-shaped while corn, rice and wheat starch granules are angular, pentagonal and angular; and spherical and lenticular–shaped, respectively. Corn, rice and wheat starch granules are less smooth–surfaced than potato starch granules. Potato starch granules are largest (<110 μm) in size followed by wheat (<30 μm), corn (<25 μm) and rice (<20μm) starches. Gelatinization temperatures (To, Tp, Tc) and enthalpies of gelatinization (ΔHgel) of starches from different sources also differ significantly. Corn and rice starches generally show higher transition temperatures than wheat and potato starches while the ΔHgel values are higher for potato and wheat starches. Potato starch shows a higher tendency towards retrogradation than the cereal starches. The rheological properties, such as storage modulus (G′) and loss modulus (G″) of the starches from the different sources increase to a maximum and then drop during heating of all the starches. Potato starch shows highest peak G′, G″ and lower tan δ than corn, rice and wheat starches during the heating cycle.

Effect of liquid whole egg, fat and textured soy protein on the textural and cooking properties of raw and baked patties from goat meat

Abstract Effects of addition of liquid whole egg (LWE), fat and textured soy protein (TSP) on textural and cooking properties of goat meat patties were studied. Textural properties of raw and baked patties were measured using an Instron Universal Testing Machine. Regression models were computed for textural and cooking properties as well as overall acceptability scores of patties as a function of LWE, fat and TSP. TSP showed greatest effect on cohesiveness, puncture force, back extrusion force and hardness of both raw and baked patties. While fat showed the highest effect on gumminess, chewiness and adhesiveness of raw patties, LWE improved the juiciness of the patties, lowered the shrinkage and cooking losses. Addition of TSP significantly decreased overall acceptability of baked patties, particularly at highest addition level (20%). The majority of the models had an R2 over 0.9, indicating they are appropriate and can be used to describe the effect of LWE, fat and TSP on textural and cooking properties of goat meat patties.

Physico-chemical, morphological, thermal, cooking and textural properties of chalky and translucent rice kernels

Studies were undertaken to compare physico-chemical, morphological, thermal, cooking and textural properties of chalky and translucent kernels separated from three rice cultivars. Physico-chemical properties, such as 1000 kernel weight, bulk density, kernel hardness, length-breath (L/B) ratio and amylose content, were determined. The morphological properties of chalky and translucent kernels were studied using scanning electron microscopy while the thermal properties were determined by differential scanning calorimetery. The chalky kernels separated from different cultivars showed higher 1000 kernel weight and bulk density but lower kernel hardness and amylose content than their counterpart translucent kernels. Microscopic analysis revealed that the cells, as well as amyloplast, were loosely packed in the chalky kernels. Chalky grains showed higher transition temperatures, enthalpy of gelatinization, peak height index and gelatinization range than the translucent grains. The cooking and textural properties of chalky and translucent kernels differed significantly. The chalky kernels from different varieties showed lower values for cooking (cooking time, water uptake, L/B ratio and elongation ratio) and textural parameters (packability, cohesiveness, chewiness, hardness) than the translucent kernels.

Some properties of potatoes and their starches. I. Cooking, textural and rheological properties of potatoes

Abstract Three different potato cultivars (Kufri Jyoti, Kufri Badshah and Pukhraj) were analyzed for cooking, sensory, textural and rheological properties. Potato cultivars (Kufri Jyoti and Kufri Badshah) with higher mealiness scores had lower cooking times and compression forces than cultivars with lower mealiness scores (Pukhraj). Kufri Jyoti and Kufri Badshah potatoes also showed higher total solids loss and water uptake values during cooking than Pukhraj potatoes. The cooked potatoes from different cultivars were also evaluated by stress relaxation test and texture profile analysis (TPA). The stress relaxation test for Kufri Jyoti and Kufri Badshah cooked potatoes yielded higher Maxwell elastic moduli (E0, E1 and E3) than Pukhraj cooked potatoes. The viscous moduli (η1,η2 and η3) were found to be significantly lower for Kufri Jyoti cooked potatoes than for Kufri Badshah and Pukhraj. TPA parameters, such as hardness, fracturability, cohesiveness and adhesiveness values, were higher for Kufri Jyoti and Kufri Badshah and were found to be related to elastic factors, such as E0, E1 and E3.

Structure and Functional Properties of Acid Thinned Sorghum Starch

The structural and physicochemical properties of acid thinned sorghum starch prepared by treating starch with 2.2 M HCl at 30°C for different durations (0–72 h) were studied. Amylose content and swelling power decreased and crystallinity increased with increase in acid hydrolysis. The scanning electron microscopy observations demonstrated that the acid thinning did not cause any disruption of the granular crystalline structure. However, the thermal properties observed by DSC showed a decrease in onset temperature (To) and enthalpy of gelatinization (ΔHgel) and an increase in conclusion temperature (Tc) upon acid hydrolysis. A significant reduction in starch pasting viscosities and gel hardness was also observed with acid thinning

Back extrusion properties of wheat porridge (Dalia)

Abstract The effects of wheat grits and sugar concentrations and temperature on the rheological characteristics of wheat porridge were investigated using the back extrusion method. Wheat porridge (Dalia) was prepared with addition of grits at concentrations of 10%, 12.5% and 15% and sugar at levels of 0%, 6% and 12% in distilled water. The porridge was back extruded at temperatures of 20°C, 40°C and 60°C. Plunger speeds varying from 100–2500 mm/min were used so that the porridge could be back extruded over a wide range of shear rates. The force displacement data were used to determine the consistency coefficient and flow behaviour index. The study revealed the non-Newtonian and pseudoplastic behaviour of wheat porridge. Wheat grits concentration had the most pronounced effect on the consistency followed by temperature and sugar concentration. Consistency coefficient increased with increasing grits and sugar concentration but decreased with increasing temperature. The consistency coefficient of the porridge samples varied from 5.9 to 241.6 Pa s n and the activation energy varied from 9.23 to 33.57 kJ/g mol. The porridge samples exhibited yield stress only at the highest grits concentration of 15% and lowest temperature of 20°C.

EFFECT OF MILLING VARIABLES ON THE DEGREE OF MILLING OF UNPARBOILED AND PARBOILED RICE

ABSTRACT Three different rice cultivars varying in length breadth ratio were parboiled. The effects of weight of sample milled and weight applied on the mill chamber on the degree of milling, length breadth ratio, head rice yield, thousand kernel weight and bulk density of milled rice were studied. It was observed that the degree of milling was inversely proportional to the weight of sample being milled and directly proportional to the weight applied on the mill chamber during milling. Parboiling led to an increase in the milling duration for the same degree of milling. Cultivars with higher length breadth ratio showed higher degree of milling for the same milling duration. The presence of husk in the mill chamber during the polishing process resulted in an increase in the degree of milling. The coefficients of regression models determined had high R 2 values and can be used to predict the degree of milling of unparboiled and parboiled rice for the three different cultivars.

EFFECT OF ADDITIVES ON DOUGH AND COOKIE MAKING PROPERTIES OF FLOUR

ABSTRACT The study was carried out to see the effect of different recipe ingredients (shortening, sodium chloride, sugar, sodium bicarbonate and water) on dough and cookie properties. Dough properties were measured using mixograph and cookie fracture force was measured using Instron Universal Testing Machine. Dough and cookie properties were described using regression to fit a response surface analysis. The models computed had correlation coefficient (R2) values ranging between 90.1–93.0%, regarded as appropriate. Shortening showed greatest effect on peak height of dough followed by sugar, sodium bicarbonate and sodium chloride. Dough development time increased with the increase in sodium chloride and decreased with the increase in shortening level. Both sodium bicarbonate and sodium chloride increased the mixing tolerance of dough. Sugar and sodium bicarbonate were observed to be the main constituents that control spread factor of cookies. Shortening improved cookie spread factor in the presence of high sugar concentration. Fracture force of cookies was observed to mainly dependent on formula water and sugar content.

Effect of Acidified Methanol Modification on Physico Chemical Properties of Black-Eyed Pea (Vigna unguiculata) Starch

Black-eyed pea starch was hydrolyzed using concentrated HCl (36% by weight) at different levels (10–60 mL) in the presence of methanol and the physico-chemical properties of native and acidified methanol modified black-eyed pea starches were compared. Results revealed high recovery (>93%) of acid-alcohol treated black-eyed pea starch upon modification. A drop in swelling power and increase in solubility was also observed during acidified methanol treatment. Acid hydrolysis increased paste clarity and the freeze–thaw stability; however, the trend was found to vary at a specific modification level. Acid thinning of starch revealed significant decrease in gel consistency, sediment volume, water, and oil binding capacity. Disruption of interactions between amylose chains resulted in increased amylose leaching on modification. The X-ray diffraction pattern of black-eyed pea starch was of C-type obtained and with increase in acid concentration the intensity of peak was found to be increased. Increased acid concentration showed significant increase in crystallinity; however, marked loss of crystallinity was observed at an acid level of 40 mL which further increased on acid concentrations of 50 and 60 mL. Also, acid concentration showed significantly improved post-reaction color difference (∆E) of the modified starches.