Volume 10, Issue 3 -

The effects of moisture content on the grinding characteristics of black soybeans were studied. The average particle size of the black soybean powder was smaller as the moisture content was decreased by drying. Bond’s constants and the work index showed lower values as the moisture content decreased. A sigmoid model accurately described the grinding kinetics of the black soybean powder ( R 2 > 0.90). The parameters in the sigmoidal models were useful to explain the effect of moisture content during grinding. However, at higher moisture contents, the sigmoid model did not accurately fit the grinding kinetics. The grinding characteristics of black soybeans showed a strong dependence on moisture content. Adjusting the moisture contents of black soybeans using a pretreatment such as drying is very important to control the grinding characteristics, including the energy consumption and the average particle size, during grinding.

The currently available technology of Makhana processing is not only indigenous and manual but also cumbersome and painstaking. The process involves handling of hot roasted seeds which require two to three laborers to process 8–9 kg of popped Makhana per day. With the view to mechanize the unit operation involved in Makhana processing, grading and roasting machine were designed and developed. Grader was developed based on engineering properties of Makhana while the roaster was designed based on preliminary experiments for Makhana, i.e. shell breaking force at different temperatures and for varying residence time. The grader performed best at feed rate of 20 kg/h with grading effectiveness of 0.99, 0.955 and 0.95 for grade 1, grade 2 and grade 3 Makhana seeds respectively. The developed roasting machine worked satisfactorily with 100% popping efficiency at machine capacity around 23.0 kg/h. The residence time of seeds in the roaster was 2.6 min and the average temperature of roasted seeds of grade 1, grade 2, grade 3 was found to be 271.33°C, 281.1°C and 280.7°C respectively.

Development of resistance during multiple foulings and three-step Cleaning-In-Place (CIP) operations, simulating an industrial cleaning regime of polysulfone ultrafiltration membranes, was investigated. The study explored how trans-membrane pressure (150 and 300 kPa) and feed protein concentration (0.9 and 10%) influenced resistance reduction during filtration and flux recovery by the cleaning procedures. New membranes, pre-cleaned with a full CIP cycle, were used for each experiment. Subsequent fouling (simulating production) and CIP were done three times in a row and the development of fouling layer resistance was monitored and evaluated. Results show that filtration performance decreased during the first days of usage, possibly related to build-up of internal fouling. Cleaning success based on flux recovery was negatively influenced by a high protein concentration in the feed, but independent of the trans-membrane pressure during filtration.

Pomegranate juice was concentrated by conventional heating at different temperatures (45, 50, 55, 60, and 65°C), and the effect of temperature on evaporation rate and on thermal degradation of total phenolics was investigated. Concentration kinetics modeling was developed based on thin-layer drying models. The logarithmic model was found to give better predictions than the others. The temperature dependence of the model constants was expressed by polynomial relationships. In addition, a first-order decay model, with an Arrhenius and a polynomial dependency on temperature and water content, respectively, was used to describe the joint influence of temperature and moisture content on the thermal degradation of total phenolics in a concentration process of pomegranate juice.

In Sub-Saharan Africa, drying maize on their stem was the traditional technique frequently used; this technique must be improved to avoid contaminations and to increase the quality of drying. However, the method of storage is accountable for the most significant losses after harvest, because mildew develops when the conditions of storage (too high temperature and moisture of the air) do not tally with the final content of the dried product. Sorption isotherms of products are most important to model moisture uptake during storage and distribution. Sorption isotherms of intermediate moisture content maize grains were determined using the gravimetric static method of saturated salt solutions at 30°C, 40°C, 50°C, and 60°C, and GAB equation was applied to discuss the results. This model correctly describes the evolutions of maize sorption isotherms, with maximum deviation of 0.0080 kg water/kg db. The net isosteric heat of sorption was determined also, using the Clausius–Clapeyron equation, and it was varied from 463 kJ/kg to 1,264 kJ/kg, decreasing with increasing moisture content. This effect was well described by an exponential function with a regression coefficient R 2 > 97%. The monolayer moisture content was found to decrease with increasing temperature. These results can be used to predict the potential changes in the stability of maize grains and later for the development of a system of suitable drying.

Physical properties of agricultural products are considered as important factors in optimization of storage conditions, packaging, transportation, water adsorption/desorption, heat, pesticides, and foodstuff moving out and also their breathing. This paper presents a time and cost economizing method to determine these important attributes of sour and sweet cherries by combining image processing and two common artificial intelligence techniques, artificial neural networks (ANNs) and adaptive neuro-fuzzy inference system (ANFIS). The measuring technique consisted of a charge-coupled device camera for image acquisition, fluorescent illuminants, capture card, and MATLAB for image analysis. Several networks were designed, trained, and generalized with a back-propagation algorithm using “ trainlm ” as training function. Several ANFIS models were designed with different number and type of membership functions (MFs) for each input. Generally, “gaussian” and “pi-shaped” MFs showed better results for estimating output variables among others. Considering statistical analysis, ANFIS showed better results than ANN.

In order to obtain re-fabricated rice with properties similar to natural rice, a special cutter and six dies were designed and evaluated. All the dimensional and physical properties of re-fabricated rice were significantly affected by die type. The average values of all the properties studied increased with the increase in moisture content (from 10 to 14%), except length/breadth ratio and porosity which decreased with the increase in moisture content. Based on the dimensional and physical properties, the re-fabricated rice obtained through die IV (8 × 1.5 mm) was in close resemblance to natural rice (PR-116). In general, uncooked and cooked re-fabricated rice grains showed significantly harder and firm texture in comparison to natural rice. Furthermore, significant differences were observed with respect to colour, whiteness and translucence between re-fabricated rice samples and natural rice. Sensory evaluation data revealed significant decrease in oral tenderness and adhesiveness in re-fabricated rice against natural rice. The study demonstrated that appropriate design of extrusion die is determinant factor for developing re-fabricated rice with properties similar to natural rice.

Cellulose fibers were obtained from corncob by using microwave-assisted chemical treatments (microwave-assisted alkaline pretreatment and microwave-assisted bleaching). These treatments efficiently removed the hemicellulose and lignin from the original corncob and increased the cellulose fiber content. The morphology, chemical structure, degree of crystallinity and thermal degradation characteristics of the resultant cellulose fibers were studied by using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. These microwave-assisted chemical treatments decreased the diameter of the cellulose fibers from 25–125 µm to 10–20 µm. The crystallinity of the corncob cellulose fibers increased from 32.7% to 73% due to the chemical treatments. The degradation temperature of the cellulose fibers was >260°C. The cellulose fibers obtained from these treatments can be used as biocomposites in reinforced polymer manufacturing.

Physical properties of fluid and semisolid foods, such as density and rheological behavior, must be carefully taken into account on designing unit operations for the processing of such kind of products. In this work, a rotational rheometer of concentric cylinders was used to evaluate the rheological behavior of red guava pulp ( Psidium guajava L.), with different soluble solids content (5, 10, and 15°Brix), at four temperatures (10, 30, 50, and 70°C). Also density data were obtained using pycnometry. Models were fitted to the obtained experimental data, in order to mathematically represent the rheological parameters and the density as functions of temperature and soluble solids content. The rheological behavior of the red guava pulp was adequately described by the Ostwald-de-Waele model, with a pseudoplastic behavior. Models to describe the simultaneous effect of temperature and concentration on the density were also presented.

In this study, the possible effect of original fluoride (F) concentration in six natural waters on the fluoride release from nine brands of tea leaves (whose origin was from Ethiopia, Sri Lanka, and China) during the infusion has been investigated. The capacity of tea leaves (commercially available tea) to absorb F from high-fluoride ground waters which were collected from the Ethiopia Rift Valley has also been investigated in this study. Infused F content of black (either powder or bag form) and green (bag form) teas and water from different sources were assayed. The fluoride content of waters used in this study ranged from 0.254 to 30.2 mg/L, while the fluoride in tea infusion of nine brands of tea ranged from 0.51 to 20.57 mg/L. The F content in moderately F-rich water was reduced from 12.5 to <5 mg/L in tea infusion while F content in highly F-rich water was reduced from 30.2 to <10 mg/L in tea infusion of most of the tea brands even with 3 min infusion time. Thus one can reduce the daily intake of F level by drinking tea rather than F-rich water itself.

The juice extracted from carambola ( Averrhoa carambola L .) fruits was used for wine production after reconstituting with distilled water, 50% ( w/v ) sugar syrup and 0.1 N oxalic acid at different concentrations to attain a range of different independent processing parameters. The processing conditions i.e., pH, fermentation temperature, inoculum size, and total soluble solids (TSS) were optimized on the basis of percentage of ethanol production. At optimum processing conditions of pH = 4.5, temperature = 26°C, inoculums size = 12% ( v/v ), and TSS = 24°B, the production of ethanol percentage in the wine was 12.15 ± 0.28% ( v/v ). At this optimum condition, the values of titratable acidity, total sugar, reducing sugar, and TSS were 0.76 ± 0.21% ( w/w ), 2.84 ± 0.22% ( w/w ), 2.65 ± 0.16% ( w/w ), and 4.6 ± 0.06°B, respectively. Color of the wine was observed to be light greenish yellow, but pH level which was 3.94 ± 0.17 was slightly higher than that of the acceptable limit. Sensory evaluation showed that the wine possessed very good taste, aroma, and clarity with moderately good body and aftertaste. It was also observed that the wine undergoes color changes during storage with more stability at lower storage temperature.

The quality of gluten-free bread made using chickpea flour and corn flour at different proportions, together with 3% (w/w) hydroxypropyl methylcellulose (HPMC) was studied. For this purpose, physical properties, crumb firmness, and micro-structure were determined. The results of these tests showed that gluten-free bread quality had been significantly improved as the concentration of chickpea flour increased. Based on the results of all performed experiments, it was concluded that the formulation containing 20% corn flour and 80% chickpea flour had the greatest effect on improving quality of the gluten-free bread.

Cherokee rose fruit (CRF) is a Chinese traditional herb which has been used in medicine for hundreds of years. The anti-tumor activity of CRF polysaccharides (CRFPs) has not yet been evaluated. To study the in vitro anti-tumor effects of CRFP and its derivatives, native CRFP was isolated from CRF by hot water extraction, and its molecular weight analyzed with gel filtration chromatography was 227,000 Da. Native CRFP was sulfated with ClSO3H-DMF and carboxymethylated with monochloroacetic acid in alkaline aqueous medium. The resulting derivatives were isolated and labeled as SF-CRFP and CM-CRFP, respectively. The in vitro inhibition rates of CRFP and its derivatives for tumor cells SKVO (human ovarian cancer cell), HepG2 (human hepatoma cell), and LoVo (human colon cancer cell) were evaluated, the result showed that native CRFP exhibited no significant inhibition effect on the three tumor cells even at a concentration of 50 μg/ml, but sulfation and carboxymethylation substantially enhanced the anti-tumor activities of CRFP in a dose-dependent way. SF-CRFP at the dose of 50 μg/ml displayed a significant inhibitory effect on SKVO, HepG2, and LoVo, with the viability rates of 33.6%, 44.8%, and 43.2%, respectively. It has a dosage-dependence inhibition on tumor growth in this model, with IC50 for SKVO, HepG 2, and LoVo being 21 μg/ml, 36 μg/ml, and 49 μg/ml, respectively. CM-CRFP showed a specific inhibition on HepG2 with a viability rate of 12.2%, with an IC50 of 17 μg/ml, while it had hardly any anti-tumor effect on SKVO cells. Thus, chemical modifications of CRFPs by sulfation and carboxymethylation effectively improved their anti-tumor properties.

Optimization of process variables for ohmic heating (OH) of fish steaks was done by response surface methodology according to Box–Behnken design. The low and high levels of the variables were 3 and 7 min for processing time; 55 and 75 V for applied voltage and 10 and 15 mm for product thickness. Responses studied comprised colour, temperature, hardness, water activity and organoleptic score. It was found that effects of time and applied voltage were significant on all responses. Optimum conditions (desirability = 0.820) obtained by numerical optimization were processing time, 5.75 min; voltage, 75 V and product thickness, 14.4 mm to achieve maximum colour variation, temperature and organoleptic score and lower hardness and water activity. Corresponding to the optimum conditions, the predicted value for temperature was 71.88°C, colour 49.85, hardness 1.125 kg, water activity 0.772 and overall acceptability 7.891.

This study presents the optimization of pre-drying treatment and storage conditions on textural and color properties of dried grapes using a response surface methodology – central composite rotatable design. Effects of three variables, potassium carbonate concentration (K 2 CO 3 , 5.98–11.02%), storage temperature (3.18–36.82°C), and relative humidity (RH, 6.96–91.04%), were evaluated. The response variables were defined as the rupture force, deformation, and Hunter L , a , and b values of dried grapes. Second-order empirical relationships with high R 2 (>0.96) values between the responses and independent variables were derived. Results also showed that the K 2 CO 3 concentration and temperature were the most significant factors influencing the studied textural and color characteristics, respectively. The overall optimum region resulted in the desirable characteristics was predicted at a combined level of 9.27% K 2 CO 3 concentration, 4°C storage temperature, and 67.34% RH. Under these conditions, the corresponding predicted response values for the rupture force, deformation, and Hunter L , a , and b values of dried grapes were 2.15 N, 2.53 mm, 28.54, 3.25, and 9.74, respectively. The predicted values thus obtained were close to the actual values indicating suitability of the models.

Rice flour, wheat flour and flour in combination (rice:wheat::50:50) were used to prepare modified flour using co-rotating twin screw extruder. The effects of barrel temperature, feed moisture and screw speed on product responses (specific mechanical energy[SME], expansion ratio and bulk density) were studied using response surface methodology. Extrusion variables were barrel temperature (125, 150 and 175°C), moisture content (14, 16 and 18%) and screw speed (300, 400 and 500 rpm). Expansion ratio was directly affected by barrel temperature, whereas increase in temperature decreased SME and bulk density. Feed moisture had positive effect on bulk density only, i.e. it increased with increase in moisture. Increase in screw speed was directly related to SME and expansion ratio. The higher R 2 values showed that the model developed for the response variables appeared adequate for predictive purposes.

The aim of this study was to find empirical models for some properties of bread dough as a function of bran concentration and particle size using D-Optimal made by Design Expert Software. Wheat flour was replaced with 0, 5, 10, 15 and 20% (w/w, flour basis) wheat bran at particle sizes of 170, 280, 425 and 750 μm. Increasing bran concentration and particle size enhanced dough water absorption. Dough arrival and development times increased, while dough stability time, tolerance to mixing and volume rising decreased as the bran particle size and concentration increased. The dough became darker, more reddish and yellower with increasing bran concentration and particle size. Dough hardness increased while cohesiveness decreased with addition of bran concentration and particle size. In general, strong correlations between dough properties with bran quantity and particle size were established. Bran concentration had stronger effect on dough properties compared to its particle size.

A closed-type water source heat pump dryer integrated with a drying programme (DP) was designed and tested. The DP was developed using psychometric conditions of desired drying air and thermodynamic balance of heat pump. A drying algorithm was developed according to the technical specification of the dryer. Drying air temperature, relative humidity and drying air volumetric flow rate were entered from a programmable logic controller (PLC) screen. In this study, the drying of mint leaves was examined. Mint leaves were dried at different temperatures (35°C, 40°C and 45°C) and at different volumetric flow rates 300 m 3 /h for a velocity of 0.75 m/s and 600 m 3 /h for a velocity of 1.5 m/s in the PLC-controlled heat pump dryer. The relative humidity of the drying air entering the dryer chamber was kept between 13.88% and 6.81% and the two air dampers were controlled according to predetermined value. The coefficient of performance (COPhp$$\rm CO{\rm P_{{\rm{hp}}}}$$) values obtained were between 3.81 and 2.29. The specific moisture extraction rate for the whole system (SMERws$$\rm SME{\rm R_{{\rm{ws}}}}$$) was between the 0.034 and 0.044 kg/kWh. The drying air temperatures were controlled with an accuracy of ±0.41°C to ±0.76°C depending on the mode of operation.

The effect of additions of Arabic gum and commercially used additive Frosty, commonly used for the bread production which is intended for freezing, on the quality of pastry sheets was determined. Frosty decreased active acidity and conversely increased titration acidity in the wheat flour dough and in final products. Higher addition of Arabic gum prolonged the freshness (= moisture) more than Frosty. Arabic gum had insignificant effect on the titration acidity or pH of the dough or the titration acidity of the final products. Both additions of Arabic gum (15 g kg −1 and 30 g kg −1 ) and higher addition of Frosty (30 g kg −1 ) decreased the firmness of the pastry sheets. Fresh samples of pastry sheets with lower addition of the Frosty were better in taste, crispness, porosity and quality than the samples with higher addition of the Arabic gum. However, pastry sheets with Frosty lost moisture faster and therefore became less fresh quicker, in comparison with samples with Arabic gum added.