Volume 6, Issue 1

This study focused on researching the effective conditions for extracting high quality apricot kernels. Specifically, we analyze the effects of moisture content and compression axis on the amount of force needed to crack apricot pits and kernels. Apricot pits were analyzed at 6.82, 12.93, 17.81 and 23.01% wet base moisture contents and apricot kernels were analyzed at 2.86, 4.10, 8.81 and 13.03% wet base moisture contents. Apricot pits and kernels were compressed at different moisture contents and the amounts of needed force for cracking were calculated along the length, width and thickness of pits and kernels. It was observed that, with increasing moisture content of the apricot pits and kernels, the energy for cracking decreased. Furthermore, this study also revealed that cracking an apricot pit requires higher rupture force and energy when compressed along its length and that cracking an apricot kernel requires higher rupture force when compressed along its thickness. Results showed that for the proper extraction of kernels, apricot pits should be compressed along its width at certain moisture content, which is very important for designing apricot pit-crushing machines.

Food materials are perishable by nature. They require processing or preservation techniques to enhance the storage life. Cryogenics is a branch of engineering wherein production of cryogen and the maintenance of low temperature technologies are studied. One such cryogen, liquid nitrogen (LN2) has a tremendous potential to be used as a total loss refrigerant. In this paper, the different aspects of the utilization of LN2 as a refrigerant and as a gas are discussed in details.In freezing for individual quick freezing LN2 can be used as a refrigerant to get an ultra rapid freezing. Due to its rapidity LN2 freezing is capable of producing small ice crystals in size and there by helps immensely in retaining quality reducing substantial amount of drip loss.LN2 has gained tremendous popularity for the transportation of frozen foods. Apart from the intermittent spraying of LN2, dump charging method has been also developed wherein the refrigerant required for a point to point transportation is supplied to a frozen cargo before the commencement of the journey eliminating the requirement of LN2 vessel to be taken on board.Grinding is a technique which reduces the size of spices, considerably increasing the surface area available to impart flavor to any prepared food. Unfortunately, a substantial amount of flavoring compounds is lost due to the increase in temperature while using conventional grinding methods. LN2 can act as a rescuer for retention of quality by reducing the spice as well as grinder temperature substantially. Experimental analysis reveals that the loss of volatile component and particle size distribution of the ground spices are more than the satisfaction level of the processor.LN2 has the capacity to both lower the temperature and flush off the inside air of a closed container. This serves a dual purpose: The temperature of the closed chamber is brought to the desired level almost instantaneously and the gas compost ion can be changed immediately. The application of LN2 helps to minimize the need for high-capacity refrigeration system. Only 10% of the installation capacity is required for maintaining the desired temperature.

Amaranth grains (Amaranthus cruentus) were air-dried at 40, 70 and 100 ºC and a moisture range from 29.5 to 10.2, dry basis (d.b.). Dried grains were wet-milled at 53.9ºC in the presence of SO2 aqueous solution in order to obtain fractions of starch, protein and fiber. Effect of drying temperature and SO2 concentration (0.01 – 0.05 w/v %) on fraction yields and protein content of starch were investigated using response surface method (RSM). A factorial design including triplicate of central point was performed. Starch and protein yields decreased as drying temperature increased while fiber yield and protein content in starch fraction shown the opposite behaviour. Protein yield and protein in starch fraction were affected negatively by SO2 concentration. Interaction among studied factors was only appreciable in fiber yield where a synergic effect was observed. The optimum conditions required to maximize starch together with the minimization of protein content in starch fraction included drying temperature of 40°C with amaranth soaking using 0.05 w/v % of SO2. These process conditions lead to 35.1 ± 1.4% of starch yield with a protein content of 1.93 ± 0.015%.

For optimization of osmotic dehydration process of aonla fruit in salt solution by response surface methodology, the experiments were conducted according to Box and Behnken design. The independent process variables for osmotic dehydration process were osmotic solution concentrations (5-25% w/v salt), osmotic solution temperature (30-60°C), solution to fruit ratio (4-8 v/w), and process time (60-240 minutes). The osmotic drying process was optimized for maximum water loss, overall acceptability and minimum solute gain, colour change, and vitamin-C loss. The optimum conditions were 22% salt concentration, 44.5°C osmotic solution temperature, 6.5 solution to fruit ratio, and 60 minutes process time. An analysis of variance (ANOVA) revealed that, among the process variable, concentration has the most significant effect on water loss, solute gain, and overall acceptability; solution temperature has the most effect on colour change; and process time has the most effect on vitamin-C loss whereas solution-to-fruit ratio observed significantly lower effect on responses.

In this study, the physicochemical properties and rheological behavior of a number of tomato pastes manufactured by Iranian food processors were compared. Chemical composition tests, color measurement, consistency and rotational viscometry were performed. There were significant differences among the samples in terms of Brix, salt level, vitamin C and Hunter color parameters (L and a/b). Some of the parameters did not pass the standard requirements set by the Institute of Standards and Industrial Research of Iran (ISIRI), e.g. Brix, color and salt. The rotational viscometry tests and shear stress–shear rate curves at 30, 45 and 60°C indicated the existence of variations among the samples in terms of apparent viscosity and yield stress. All tomato paste samples in this study were non-Newtonian fluids and the apparent viscosity of the pastes decreased with temperature increase. The rheological data obtained were fitted using a Power Law equation. The differences were attributed to raw material variations and processing conditions.

Curdlan is a water insoluble polysaccharide composed exclusively of ?-(1, 3) linked glucose residues. Agrobacterium sp. is known to produce extracellular curdlan under nitrogen-limited conditions. The purpose of this study was to investigate the effects of pH, amounts of ammonium, sucrose and trace elements, and time the addition of sucrose, ammonium and uracil on the production of curdlan in a shake flask and to further scale-up the process to a 5 L fermentor. A maximum of 48.7 g L-1 of curdlan was obtained in a shake flask when 150 and 1.4 g L-1 of sucrose and ammonium were used at the initial pH of 6.5. The production was enhanced to 57 g L-1 by adding one third of sucrose and 1 g L-1 of uracil at the 48th h in a fed batch mode. The process was scaled up to a 5 L bioreactor in a batch mode where the oxygen transfer rate was higher (0.192 mg L-1s-1) when compared to that in the shake flask (0.096 mg L-1s-1). Curdlan production was 58 g L-1 in the bioreactor, which was higher than the shake flask under batch conditions (48.7 g L-1). The viscosity average molecular weight of the curdlan produced was found to be 1.4 × 105.

The Finite Element Method was used to calculate the heat transfer processes that take place during cooking of meat emulsions formulated with different amounts of pork fat or olive oil. Experimental data acquired in the pilot plant were used to validate the theoretical model obtained by computer simulation. The results indicate that the computer simulation predicts to a good approximation. The most important parameters were cooking time and temperature of the meat emulsions. In addition, the theoretical model provides information about the temperature fields for all points in the meat emulsion. For a given fat content, no differences were found in the thermal properties of the emulsions elaborated with pork back fat or olive oil (p >0.05). Instead, the different fat and water content of the meat emulsion formulation determined the differences in the temperature-time evolution during the cooking process.

A non-isothermal (linearly increasing temperature) procedure was used to determine the moisture diffusivity in mass transfer as a function of temperature with the complex optimization method. The effects of heating rate and experimental errors on the prediction accuracy of the parameters in Arrhenius equation were evaluated through pseudo-experimental data randomly generated on the basis of simulation results. An optimum heating rate of 0.01 K/s was found at which the experimental error less than 15% has negligible effect on calculated liquid diffusivity.

Deep-bed drying is an integrated process affected by many different factors. In this regard, the nature of deep-bed drying phenomenon was discussed, and the models and mass equilibrium equations for deep-bed hot-air drying process were constructed for the study. The material dehydration process, medium humidification process and system equilibrium were analyzed. The dimensionless numbers were introduced to simplify and solve the differential equations of deep-layer drying. Furthermore, the analytical formula and solution of the deep layer hot-air drying process were given. The results provided a kind of simple and practical analytical formula and calculation method, which are the base to hold the characteristics of deep-layer drying system well, and realize the accurate control of process.

A scaling-up approach from drying of a thin layer wet material in a experimental tunnel to a pilot scale spray drying was developed through determining drying kinetics of quick evaporation process. Maltodextin was selected as solid material in solution to be dried. Critical moisture contents as a function of initial water evaporation rate (drying rate) shows that there is the same variation between the small scale test tunnel and the pilot scale spray dryer. Result of CFD modelling demonstrates that drying kinetics obtained from the small-scale tunnel could be properly applied to scale-up the spray drying process.

Pineapple samples were dried in normal and modified atmospheres by addition of 0.5% ethanol v/v to the air stream using two different temperatures and two different velocities. The volatile composition changes during the drying process were determined using the solid phase microextraction coupled to a gas chromatographer with mass spectrometer. The modification of the drying atmosphere with ethanol vapor promoted a more intense water evaporation as well as a less pronounced loss of volatiles. The volatile composition changed significantly during drying not only by the loss of some components but also by the appearance of others.

Oscillating heat pipe is a new type high efficiency heat-transfer element. Its development and design attract increasing attention. This paper describes a numerical simulation for investigating on the flow and heat exchange performance of an oscillating heat pipe heat exchanger. The influences of the arrangement of heat pipe, the inlet temperature and the flux of hot air were explored. The results show that the heat exchange of staggered arrangement is more efficient than the aligned one. The influence of temperature difference on the heat exchanger by hot air flux is more than hot air inlet temperature.

The effect of pretreatments (water and steam blanching and by soaking in osmotic solutions of 60 and 70° brix) on drying behaviour of chili pepper dried at 60°C were investigated. During the experiments, the chili pepper was dried until there was no more water loss. The pre-treatment affected the course and rate of drying since the pretreated pepper dried faster than the untreated pepper and hence had a higher drying rate. The drying of the pepper occurred in the falling rate drying period. Four mathematical models were studied for the description of thin layer drying characteristics of the chili pepper. The models considered were the Newton, Henderson and Pabis, Logarithmic and Page model. Comparing the correlation coefficients (R2), chi-square (?2), mean bias error (MBE) and root mean square error (RMSE) values of the four models, it was concluded that the Page model represents the drying characteristics better than the other models.