Number Of Food Applications Research Articles

Heat stability of high-protein ultrafiltration retentate: Effect of concentration factor and stabilizing salts

Pasteurized cow skim milk (PCSM, 1×) was concentrated using ultrafiltration (UF) from 2 ×-7 × concentration factor (CF) to obtain retentates with different protein to total solids (TS) ratio. Alteration in chemical make-up led to poor thermal stability in UF retentates. Therefore, this study was aimed to investigate the changes in permeate flux, chemical composition, pH, viscosity and heat coagulation time (HCT) of UF/DF retentates as a function of CF. Impact of high-shear (20,000 rpm/ 5 min), diafiltration (DF) with 150mM NaCl solution and stabilizing salts on HCT of high-protein 7×UF retentates were also evaluated. With increase in CF; TS, protein, fat, ash, calcium contents and viscosity increased significantly (p<0.05), while permeate flux, lactose content, pH and HCT of retentates significantly decreased (p<0.05). Poor HCT (1 min) of 7×UF retentate was significantly increased (p<0.05) up to 60 min by addition of stabilizing salts (NaH2PO4, Na2HPO4 and Na3C6H5O7). Correlation was established between chemical constituents, pH, viscosity, HCT, permeate flux and concentration factor. Overall, this investigation established that identification of correct stabilizing salts via HCT-pH curve of PCSM and their appropriate addition converted thermally unstable (poor HCT) high-protein (7× UF) retentates to thermally stable product. Hence, they could be now explored in number of food applications.

Investigation of moisture sorption behavior of soluble sodium caseinate

Casein is a potential food protein, used in a number of food applications. In this work, moisture sorption isotherms of casein were determined at 10, 20 and 30 o C under different relative humidity in the range of 12 to 98 percent using gravimetric method. The equilibrium moisture uptake data were interpreted with the help of three well-known sorption isotherm models namely, (GAB, Halsey and Oswin models) using non-linear least square method. The experimental moisture uptake data were best interpreted by GAB model. The monolayer moisture content X m was found to vary from 54.08 x 10 -3 to 10.48 x10 -3 kg kg -1 (db) for a temperature rise from 10 to 30 o C, thus indicating negative temperature dependence. The Clausius-Clapeyron equation was used to determine the isosteric heat of sorption (q st ). The uptake data was also used to determine isokinetic temperature T β (315.9 K) and harmonic mean temperature T hm (292.8 K). The enthalpy-entropy compensation theory indicated that moisture sorption process was enthalpy driven.

Modification of whey protein concentrate hydrophobicity by high hydrostatic pressure

The objective of this study was to evaluate the influence of high hydrostatic pressure (HHP) treatments on hydrophobicity of whey protein concentrate (WPC). An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity, which is positively correlated with functional properties. The effects of HHP treatment (600 MPa, 50 °C, 0 to 30 min) on intrinsic fluorescence of WPC and the binding properties of WPC for aromatic 1-anilino-naphthalene-8-sulfonate (ANS) and aliphatic cis-parinaric acid (CPA) probes were studied. HHP treatment of WPC resulted in an increase in intrinsic tryptophan fluorescence intensity and a 4 nm red shift after 30 min of treatment, which indicated changes in the polarity of tryptophan residues microenvironment of whey proteins from a less polar to a more polar environment. There was an increase in the number of binding sites of WPC for ANS from 0.16 to 1.10 per molecule of protein after HHP treatment for 30 min. No significant changes in the apparent dissociation constant of WPC for ANS were observed after HHP treatment, except for an increase from 1.8 × 10 −5 M to 3.3 × 10 −5 M after 30 min of HHP treatment. There were no significant changes in the number of binding sites of WPC for CPA. However, increased binding affinities of WPC for CPA were observed after the come-up time or 10 min of HHP treatment, with a decrease of apparent dissociation constant from 2.2 × 10 −7 M to 1.1 × 10 −7 M. The binding sites of WPC may become more accessible to the aliphatic hydrophobic probe CPA after the come-up time or 10 min of HHP treatment. These results indicate that HHP treatment of WPC yields increases in the number of binding sites for an aromatic hydrophobic probe, while aliphatic hydrophobic binding affinity of WPC is enhanced after come-up time or 10 min of HHP treatment. Industrial Relevance Text The functionality of protein molecules depends on hydrophobic, electrostatic, and steric parameters of the protein structure. Modifications of proteins that enhance hydrophobicity show promise for improving functional properties of foods. An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity. High hydrostatic pressure (HHP) affects the hydrophobicity of beta-lactoglobulin (β-LG), the primary protein in whey, and increases the binding affinity of β-LG for 1-anilino-naphthalene-8-sulfonate and cis-parinaric acid. However, little work has been done regarding the effects of HHP on whey protein concentrate (WPC) hydrophobicity and flavor-binding properties, and whether the presence of multiple proteins in WPC has significant influence on the behavior of whey proteins during HHP treatments. WPC is a good candidate for testing the practical utility of the application of HHP to modify the functional properties of a complex protein system since it is in the form that the ingredient is utilized in a number of food applications. The current work describes the effects of HHP on hydrophobicity of WPC and potential applications.

Promotion of intestinal tumor formation by inulin is associated with an accumulation of cytosolic beta-catenin in Min mice.

Inulin, polydisperse beta (2-1) fructan, has been suggested to protect against colon carcinogenesis and is currently used in a number of food applications. However, the data regarding the role of inulin in intestinal carcinogenesis remains controversial since the results of our previous study suggested that inulin promotes intestinal tumor formation in Min mice, an animal model for intestinal cancer with a mutation in the Apc tumor suppressor gene (Carcinogenesis 2000;21:1167-73). In our present study, we further examined the effects of inulin on intestinal tumor formation in Min mice by carefully analyzing beta-catenin expression and cellular localization at 3 different time points during the tumorigenic process. Min mice were fed a high-fat inulin-enriched (10% w/w) diet or the high-fat diet without any added fiber from the age of 6 weeks to the ages of 9, 12 or 15 weeks. The results showed that inulin significantly increased the number (by 20%) and especially the size (by 44%) of adenomas in the small intestine. At week 15, the promotion of tumor development was accompanied by an accumulation of cytosolic beta-catenin in the adenoma tissue. In the normal appearing mucosa, levels of membrane beta-catenin and PCNA were reduced in the inulin-fed mice, possibly indicating impaired enterocyte migration. These data do not support the earlier suggestions on the cancer preventive effects of inulin and emphasize the need for further research and evaluation where health claims for inulin are concerned.

Preservation and fermentation: past, present and future

Preservation of food and beverages resulting from fermentation has been an effective form of extending the shelf-life of foods for millennia. Traditionally, foods were preserved through naturally occurring fermentations, however, modern large scale production generally now exploits the use of defined strain starter systems to ensure consistency and quality in the final product. This review will mainly focus on the use of lactic acid bacteria (LAB) for food improvement, given their extensive application in a wide range of fermented foods. These microorganisms can produce a wide variety of antagonistic primary and secondary metabolites including organic acids, diacetyl, CO 2 and even antibiotics such as reuterocyclin produced by Lactobacillus reuteri. In addition, members of the group can also produce a wide range of bacteriocins, some of which have activity against food pathogens such as Listeria monocytogenes and Clostridium botulinum. Indeed, the bacteriocin nisin has been used as an effective biopreservative in some dairy products for decades, while a number of more recently discovered bacteriocins, such as lacticin 3147, demonstrate increasing potential in a number of food applications. Both of these lactococcal bacteriocins belong to the lantibiotic family of posttranslationally modified bacteriocins that contain lanthionine, β-methyllanthionine and dehydrated amino acids. The exploitation of such naturally produced antagonists holds tremendous potential for extension of shelf-life and improvement of safety of a variety of foods.