Band 5, Heft 3

A combined membrane process has been used to fractionate skim milk. Microfiltration and ultrafiltration were employed to obtain concentrates with different protein/lactose ratios depending on the volume concentration ratio to produce protein enriched yoghurt. Nanofiltration has been used for lactose recovery from the ultrafiltration permeate with partial demineralization, while the permeate water of NF can be reused or recycled. Feed, permeate, concentrates and yoghurt have been physicochemical characterized and compared with commercial products. The obtained yoghurts have a smooth aroma and an agreeable taste, the protein content increased up to 50 % and the lactose content decreased approximately 50 % in comparison with commercial yoghurts, while calcium and iron were also increased, leading to a product with special characteristics and high commercial value. Lactose powder has been obtained by lyophilization; the product has good solubility and has 90% purity which can be used in different food preparations or for other applications.

An experimental storage based on the principle of evaporative cooling was designed to evaluate the performance of three natural absorbent fiber materials to be used as cooling pads. The absorbent materials were jute, hessian and cotton waste. The performance criteria included cooling efficiency, material performance and total amount of heat load removed from the evaporative cooler. The results showed that under the no-load condition, the average cooling efficiency was highest for jute at 86.2%, compared to 76.3% for cotton waste and 61.7% for hessian fiber. Materials performance tests results showed that the highest resistance to mold formation was exhibited by hessian followed by cotton waste, while the jute fiber had very poor performance. The heat load determination also showed that products stored in the cooler with jute as water absorbent produced the least heat of respiration, followed by cotton waste and hessian in that order. The total results indicated that jute had the overall advantage over the other materials. However, if the cotton waste surface could be modified to offer larger surface required for evaporation, it would be the best alternative because the jute surface is prone to mold formation.

The risk of a salmonellosis outbreak from consuming contaminated eggs is a societal and governmental concern. The bactericidal efficiency of electrolyzed oxidizing (EO) water for inactivation of salmonella and artificially inoculated shell eggs were evaluated in this study. The effects of available chlorine concentration (ACC, 0.1-2.0 mg/l) and pH value (2.3, 3.5, 4.6, 5.7 and 6.5) on the bactericidal activity of EO water were investigated by using pure cultures (7.0-8.0 log10 CFU/ml) of Salmonella pullorum and Salmonella enteritidis strains. EO water was effective for inactivation of both pathogens. The bactericidal activity increased with increasing the ACC of EO water. The bacteria were completely inactivated when the ACC of EO water was higher than 1.0 mg/l. At a sufficient ACC (greater than 3.0 mg/l), the bactericidal activity of EO water was independent of its pH value. A 100% inactivation (reduction of 6.7 log10 CFU/g) of both pathogens on the surface of shell eggs was achieved at an ACC of 20 mg/l except for the treatment of EO water spraying. Shell eggs soaked in alkaline electrolyzed water followed by soaked in EO water was more effective to reduce the viable counts of both pathogens compared to EO water used alone. No survival of both pathogens was detected in EO water after washing treatment. Results indicated that EO water is a promising and powerful disinfectant agent for shell eggs washing processing.

In this study, starches were extracted from two cultivars of local Irish potatos (Solanum tuberosum,) and tree cultivars of local Cassava (Manihot esculanta). These starches and a commercial Irish potato starch (IPS), where characterized with respect to their physico-chemical and functional properties. Significant differences (P<0.05) were observed among starches as far as their proximate composition were concerned. The commercial starch showed the highest phosphorus content. The amylose content was observed to be significantly lower (P<0.05) in the cassava starches than in the local Irish potato starches. The highest (P<0.05) gelatinisation parameters were those of 2425 starch cultivar. Potato starch granules exhibited the largest granule size at 10, 50 and 90% diameter compared to those of cassava starches. Potato starches had wider particle size distribution compared to cassava starches. There were apparent differences, between species (Cassava and potatoes) with respect to granule morphology and size. No significant colour difference (P>0.05) was observed between the Sipiera starch cultivars and the Irish potatoes commercial starch.

A sterilized mixed herbal drink formula and process was developed for the mixed herbal extracts from Imperata cylindrical (L.) P. Beauv [IC], Murdannia loriformia (Hassk.) Rolla Rao et Kammathy [ML], Hedyotis corymbosa Lamk. [HC] and Orthosiphon aristatus Miq [OA]. Increasing extraction temperature and time decreased the antioxidant activity and increased the total potassium and phenolic compound contents of the herb infusions. Using response surface methodology (RSM), the appropriate extraction condition was 74.6°C for 41 minutes. The most acceptable formula contains a % weight ratio (w/w) of 14:35:27:17of IC: ML: HC: OA infusions to 7% (w/w) sucrose. Decreasing the sterilization temperature and increasing the F0-value reduced the antioxidant activity and total phenolic compounds. The appropriate sterilization temperature and F0 were 135°C and 3 minutes.

This article aims at determining thin-layer drying curves for grains of lima bean, variety olho-de-peixe and to predict them using diffusion models. Samples of lima bean (110.0 g) with initial moisture content of 66.0% (wet basis, wb) were dried at temperatures of 40.0, 50.0 and 60.0°C. The effective diffusivity of moisture was determined by analytical solutions of the mass diffusion equation (Fick’s second law) with prescribed boundary condition for spherical, cylindrical, and infinite slab at each temperature. Comparison with the experimental data showed that the infinite slab with constant diffusivity predicted more accurately, but statistical indicators of the goodness of fit were not completely satisfactory. Thus, a model for the infinite slab with constant volume, moisture-dependent diffusivity and convective boundary condition was numerically integrated. This model was solved by the numerical method of finite volumes with fully implicit formulation. The values obtained for the diffusivity were between 5.58 x 10-9 and 6.39 x 10-8 m2 min-1, being the activation energy 28.4 kJ mol-1. The model satisfactorily describes the drying process of this lima bean cultivar under all conditions investigated.

Creep properties of four varieties japonica cooked rice were tested using a dynamic mechanical analyzer (DMA Q800). The creep curve was described by Burgers model. The creep process of japonica cooked rice mainly consisted of retarded elastic deformation, ?R and viscous flow deformation, ?V, and negligible instantaneous elastic deformation, ?E. The retarded elastic modulus, ?2, relaxation time, ?, and the viscosity coefficient, ?1, of the cooked rice according to the Burger model were estimated through nonlinear regression. The effect of the chemical compositions on the rheological parameters based on creep behavior of cooked rice was assessed. Correlation analysis indicated that the retarded elastic modulus, ?2, had positive correlations with protein (r = 0.952, P = 0.048). The relaxation time, ?, had negative correlation with protein content (r = -0.909, P = 0.091). The viscosity coefficient, ?1, was negatively correlated to amylose (r = -0.915, P = 0.085). The analysis between creep parameters and sensory evaluation showed that the viscosity coefficient, ?1, positively correlated to stickiness and total evaluation of cooked rice. So it can be used to evaluate the eating quality of cooked rice.

A mathematical model with distributed parameters was proposed to describe the absorption of water by soybeans, in order to evaluate the moisture content variation with time inside the grains. This model was represented by a partial differential equation (second order relative to position and first order relative to time), whose parameters were numerically adjusted using a minimum squares method. For this purpose, available MATLAB® routines were used, together with experimental data obtained from hydration tests where soybeans were immersed in liquid water at temperatures of 10, 20, 30, 42 and 49°C. According to the results, the model was able to represent the main characteristics of the hydration process, with a maximum deviation of 10% in the whole set of experimental conditions.

In this study, the acid hydrolysis of inulin was investigated as a function of three variables: pH, temperature and time. Inulin hydrolysis was detected by measurement of reducing sugars, using Dinitro Salicylic acid (DNS) method. The central composite rotatable design (CCRD) was applied to design an experimental program to model the effects of acidic and alkaline pH on the inulin hydrolysis. Additionally, response surface methodology (RSM) was utilized for data analysis. The statistical analysis of the results confirmed that pH, temperature and time are significant variables at acidic pH, whereas at alkaline pH, these variables are insignificant. The maximum amount of inulin hydrolysis obtained at the pH < 2, temperature > 90°C and the time of 1 hrs.

In this work the rheological behavior of two varieties of honey were evaluated using a Brookfield viscometer R.V.T in a temperature range of 5-20°C. In order to interpret the experimental results in terms of viscosity, the torque-speed data and scale readings were converted into shear stress-shear rate relations using numerical conversion values proposed by Mitschka. This method offers excellent potential for quality control testing in the food industry. Samples exhibited Newtonian behavior and the temperature effect on the viscosity followed an Arrhenius-type relationship.

The present paper studies the influence of different nutrients for the production of two cellulolytic enzymes: endo beta-1.4 glucanase and exo beta- 1.4 glucanase by anaerobic fungi taken from cow rumen, that were fed a diet of corn silage and Brachiaria decumbens grass hay. During the enzymatic degradation assays, it was observed that the addition of some essential nutrients in the formulation of the culture medium contributed positively in the cellulolytic enzyme production, with exception of riboflavin. Such results contributed in the establishment of an effective method for the evaluation of enzymatic activities in anaerobic fibrolytic fungi. In this work, nutrients added to enrich the culture medium have successfully proven that they can be used as inoculating agents (inductors) in diets rich in ensilage with law nutritive value.

Gluten is widely discussed in dough and breadmaking subjects but the focus has not been on the production of gluten itself for usage and application in the food industry. This paper presents some modelling studies of gluten production using response surface methodology (RSM) by varying three main factors that contribute towards gluten formation during dough mixing, which are the mixing time, salt and water levels. The gluten produced was measured for its quantity in terms of wet and dry gluten contents and for quality, in terms of volume expansion of fried gluten and extensibility of gluten. Two wheat flour types, the strong and weak were used as comparison. The experiment was designed following a standard RSM design, known as the central composite design. The results of analysis of variance indicated that the proposed mathematical model obtained can adequately describe the production of gluten within the studied factor limits. The coefficient of determination, R2 of all the responses were higher than 0.80. Results show that salt gave the most significant effect (0.0001

Response surface methodology was used to determine the optimum processing conditions that yield maximum water loss and weight reduction and minimum solid gain during osmotic dehydration of radish in salt solution. The experiments were conducted according to Central Composite Design (CCD). The independent process variables for osmotic dehydration process were temperature (25 – 45°C), processing time (30 -150 minutes), salt concentrations (5 - 25% w/w) and solution to sample ratio (5:1 – 25:1). The osmotic dehydration process was optimized for water loss, solid gain, and weight reduction. The optimum conditions were found to be: temperature – 36°C, immersion time - 95 min, salt concentration – 25% and solution to sample ratio 15:1. At this optimum point, water loss, solid gain and weight reduction were found to be 34.5 (g/100 g initial sample), 2.2 (g/100 g initial sample) and 32.1 (g/100 g initial sample), respectively.

An improved process with commercial wine yeast Saccharomyces cerevisiae Montrachet was developed for co-production of betacyanine (a natural red beet pigment) and red beet eau-de-vie from the juice of red beet roots (Beta vulgaris). Red beet wines contained more than 55 g/L ethanol and approximately 0.95 g/L betacyanine. The samples of red beet eau-de-vie prepared by distillation of red beet wines had 180 g/L ethanol and the stillages contained nearly 2.5 g/L betacyanine.

Chapatti, Indian unleavened flat bread made of whole-wheat flour, is traditionally prepared in households by hand sheeting of dough followed by baking on hot griddle and is consumed fresh. Investigations were made to study the effect of guar gum on whole wheat chapatti dough stickiness and its effect on staling of chapatti during storage. Guar gum was incorporated at various levels ranging between 0.25-1.0% w/w of whole wheat flour. Chapatti dough was prepared and evaluated for dough stickiness using Chen-Hoseney dough stickiness probe. Chapattis were prepared and monitored for staling parameters such as water soluble starch (WSS), moisture content, in vitro enzyme digestibility (IVED), extensibility and tear force, both when fresh and after storage for three days at room temperature (30±2 °C) and refrigerated temperature (4±1 °C). From the study it was observed that guar gum prevented staling in chapattis as was monitored through various parameters. Moisture, WSS, IVED content in guar gum incorporated chapatti was higher than the control chapatti. The force required to tear fresh chapattis was decreased with hydrocolloid addition however guar gum addition at 0.75% w/w of whole wheat flour gave the softest chapatti. Extensibility of stored chapatti was significantly decreased with storage, both at room and refrigeration temperature. However, refrigerated chapatti containing guar gum showed less loss in extensibility, up to a period of three days.

The effect of moist and dry heat processing on lysine content of selected foods was investigated. Two moist heat (open and closed vessel) and dry heat (microwave and hot air oven) methods were chosen for processing samples from cereal, oilseed and pulse groups with whey protein concentrate as reference sample. Unheated samples served as controls. The samples were analysed for protein content, available lysine by fluorodinitrobenzene method and for in vitro protein digestibility (IVPD). Results indicated that in moist heat-treated samples lysine retention was between 69 – 83%. Dry heat treatment resulted in a greater loss of lysine, which was proportional to the degree of heating. The retention of lysine in dry heat-treated samples ranged from 31 to 65 %. All heated samples had higher digestibility than their raw controls. In between methods of heating, the IVPD of dry heat-treated samples were slightly lower than moist heat-treated samples. It can be concluded that heat treatments increase the in vitro digestibility of proteins but lysine content was affected adversely.