Biomedical subjects

H K Vyas

Publications and source records attributed to H K Vyas.

4 recordsLinked to original sources

PubMed2004

Impact of source and level of calcium fortification on the heat stability of reconstituted skim milk powder.

Calcium enrichment of food and dairy products has gained interest with the increased awareness about the importance of higher calcium intake. Calcium plays many important roles in the human body. Dairy products are an excellent source of dietary calcium, which can be further fortified with calcium salts to achieve higher calcium intake per serving. However, the addition of calcium salts can destabilize food systems unless conditions are carefully controlled. The effect of calcium fortification on the heat stability of reconstituted skim milk was evaluated, using reconstituted skim milks with 2 protein levels: 1.75 and 3.5% (wt/wt) prepared using low and high heat powders. Calcium carbonate, phosphate, lactate, and citrate were used for fortification at 0.15, 0.18, and 0.24% (wt/wt). Each sample was analyzed for solubility, heat stability, and pH. The addition of phosphate and lactate salts lowered the pH of milk, citrate did not have any major effect, and carbonate for the 1.75% protein samples increased the pH. In general, changes in solubility and heat stability were associated with changes in pH. Calcium addition decreased the solubility and heat stability. However, interestingly, the presence of carbonate salt greatly increased the heat stability for 1.75% protein samples. This is due to the neutralizing effect of calcium carbonate when it goes into solution. The results suggested that the heat stability of milk can be affected by the type of calcium salt used. This may be applied to the development of milk-based calcium enriched beverages.

Animals↗

PubMed2004

Characterization of particles in cream cheese.

Cream cheese is used as a spread and as an ingredient in many food applications. A gritty or grainy mouthfeel is an undesirable textural defect that occurs in cream cheese. However, the factors that cause the textural defect are not well understood. The objectives of this study were to isolate and characterize particles from cream cheese and to study the effect of particles on cheese texture. Particles were isolated by washing cream cheese with water first at 25 degrees C and then at 50 degrees C repeatedly 4 to 5 times. The size of these particles was determined using a particle size analyzer. The particles as well as the original cheeses were analyzed for moisture, fat, protein, ash, and lactose. The particle size ranged of 0.04 to 850 microm. It was found that isolated particles were significantly higher in protein content as compared with the whole cheese. To study the effect on the cheese texture, particles were added at 5, 15, and 25% (wt/wt) levels to smooth cream cheese, and a sensory ranking test was done on the samples. Isolated particles were further separated into 2 size classes of 2.5 to 150 microm and > or =150 microm. These particles were then mixed with smooth cream cheese at 16 and 29% (wt/wt), and a sensory test was conducted on these samples. Smooth cream cheese with only 5% (wt/wt) added particles was perceived as significantly grittier than the control sample. This experiment also revealed that the perceived grittiness increased with increase in amount and size of particles.

Caseins↗

PubMed2003

Process for calcium retention during skim milk ultrafiltration.

Lactose is separated from milk or other fluid dairy products for a variety of reasons. Ultrafiltration is a known process of removing lactose from these products. However, during ultrafiltration, valuable minerals, such as calcium in soluble form, are also lost into permeate. In this study, a process was developed in which first the lactose reduction in skim milk was achieved by ultrafiltration (4x volumetric concentration) using a 10-kDa membrane. Then, the calcium present in permeate was precipitated using one of three methods: 1) heat treatment, 2) pH adjustment, or 3) a combination of pH adjustment and heat treatment to permeate, then recovered by refiltering permeate. The process was first developed at laboratory scale, and then its applicability was tested at the pilot scale. Skim milk, retentates, permeates, and the treated permeates were analyzed for total solids, ash, protein, or total nitrogen, calcium, and lactose content. About 76% of the total lactose and about 16% of the calcium present in skim milk permeated through the membrane during ultrafiltration. The three treatments applied produced white precipitates and turned the clear permeates turbid. On refiltering the treated permeates approximately 42, approximately 50, and approximately 70% of the total calcium present could be recovered from 1) heat-treated, 2) pH-adjusted, and 3) pH-adjusted and heat-treated permeates, respectively. There was no marked change in the lactose content due to any of the three treatments and subsequent refiltering of the treated permeates.

Animals↗

PubMed2002

Scale-up of native beta-lactoglobulin affinity separation process.

Affinity separation of beta-lactoglobulin in its native form with all-trans-retinal immobilized on calcium bio-silicate was scaled up and applied to separate it from industrial sweet whey. Three different methods of mixing the modified calcium bio-silicate and whey for the interaction between all-trans-retinal and beta-lactoglobulin were tried at pilot scale. The three methods used were 1) a column packed with calcium bio-silicate, 2) a stirred tank, and 3) a fluidized bed column of calcium bio-silicate particles. Adsorption and desorption of beta-lactoglobulin were carried out at pH 5.1 and 7.0, using 0.01 and 0.1 M phosphate buffers, respectively. The phosphate buffer containing desorbed beta-lactoglobulin was concentrated 20 times using ultrafiltration and then freeze-dried. The packed column, stirred tank, and fluidized bed column produced beta-lactoglobulin with purity of 80, >95, and >95%, and recovery of 0.65, 2.88, and 2.88 g per kilogram of calcium bio-silicate, respectively. The comparative poor purity and recovery of beta-lactoglobulin in the case of the packed column was attributed to insufficient contact between the passing fluids and the calcium bio-silicate during adsorption, desorption, and intermittent washing. The fluidized bed column method, with a gentle mixing action, was considered the best suited for further scale up to the industrial level.

Adsorption↗