Volume 9, Issue 1 -

Biologically active peptides as components in functional foods exhibit diverse activities and exert health effects in humans, just as the angiotensin I-converting enzyme (ACE)-inhibitory peptide exerts an antihypertensive effect. The solid-state fermentation of soybean meal was conducted using Bacillus subtilis natto at an appropriate temperature to accelerate proteolytic hydrolysis, and the crude extract containing ACE-inhibitory peptides was sequentially purified by ultrafiltration, gel chromatography and reverse phase-HPLC. A novel ACE-inhibitory peptide was obtained and its ACE-inhibitory activity was 84.1% with an IC 50 value of 0.022 mg/ml. The results suggest that these ACE-inhibitory peptides obtained from the solid-state fermentation of soybean meal using B. subtilis natto have good potential for application in the management of hypertension and the fermented soybean meal has good potential for application in the production of a novel physiologically functional food.

In order to effectively process and utilize surplus bananas and those without the quality for export, in this research it is proposed to microencapsulate the banana juice by means of spray drying and using maltodextrin as the covering material. Three cultivars Enano gigante (Musa AAA, subgroup Cavendish), and the tetraploids hybrids (AAAA), FHIA-17 and FHIA-23 were selected for this research. Being Enano gigante, the cultivar shows the highest glass transition temperature. The drying parameters were established, depending upon the ratio of juice/maltodextrin and the drying air temperature. The optimal drying air temperature was 220°C for the three cultivars with a 20% juice/maltodextrin ratio for both the Enano Gigante and the FHIA-23, while in the FHIA-17 there were no significant differences between the juice/maltodextrin ratios. The morphology and size distribution of the microcapsules were observed by a scanning electron microscopy. The number of particles is directly proportional to the temperature and inversely proportional to the juice/maltodextrin ratio. A Weibull particle size distribution was common to all treatments. There is a correlation between the principal components and clustering analyses with the optimization of the system. The principal components analysis considers three Weibull parameters (obtained from the particle size distribution) and the powders moisture percentage.

In this study, wheat flour was replaced and/or substituted with bambara groundnut flour. Four blends were prepared by mixing the wheat flour with bambara groundnut flours in the proportions of 100:0 (WWB), 75:25 (BGFB-25), 50:50 (BGFB-50), and 0:100 (BGFB-100). These blends were then fortified with powdered orange peels (3%), for the production of biscuits. The sensory evaluation of the biscuits revealed that there was no significant difference ( p > 0.05) between all the biscuits in aroma, color, and texture, while significant difference was observed in their taste and general acceptability; with WWB ranking the highest in taste and general acceptability. Aqueous extracts of biscuits were prepared. The result revealed that biscuit extracts exhibited good antioxidant [DPPH (1,1-diphenyl-2-picrylhyrazyl) and ABTS (2,2-azinobis-3-ethylbenzo-thiazoline-6-sulfonate) radical scavenging abilities and reducing property] and enzyme (α-amylase and α-glucosidase) inhibitory properties (in vitro). The inhibitory effects on α-amylase and α-glucosidase could be attributed to the phenolic contents and antioxidant properties of the biscuit extracts; moreover, BGFB-100 showed the highest antioxidant and enzyme inhibitory properties.

To increase the dietary fiber of sponge cake, it was enriched with wheat bran of different levels (0, 5, 10, 15, and 20%, w/w; flour basis) and particle sizes (90, 170, 280, and 420 μm). The results showed that both crude fiber and phytic acid contents of the bran decreased with the reduction in the particle size. Batter density increased whereas batter consistency decreased with increase in the particle size and the level of the bran. The crust and crumb color became darker, more reddish and less yellowish as the level and particle size of the bran increased. Density of the cakes decreased as higher percentages and coarser brans were included. Determination of the textural properties of the cakes using texture profile analysis technique showed that with increase in the percentage of wheat bran, hardness, gumminess, and chewiness increased whereas, cohesiveness and springiness decreased. According to the taste panel, using no more than 10% bran with particle size smaller than 170 μm resulted in cakes similar to the control. The total dietary fiber and phytic acid content of the resultant cakes was 5.95% and 2.90 (mg/g), respectively.

A group of cassava landraces that occur naturally in Amazonia ( Manihot esculenta Crantz) are known as mandiocaba or sugary cassava because they have high free sugar content, making them a possible feedstock for the production of syrup. The objective of the study was to evaluate the technological viability of obtaining sugary cassava syrup and to characterize the physical and physicochemical properties of the product. The yield of the syrup (80 °Brix) obtained from the manipueira (liquid obtained by crushing and filtering the cassava) concentration was 262.72 g per plant. The reducing sugars represented 77.26% of total sugars, the density was 1.4210 g cm –3 at 20°C, and the volumetric expansion coefficient was 38.6 m K –1 . The Newtonian behavior and activation energy (≥69.65 kJ gmol –1 ) were similar to that of honey found in the literature.

In this study, grey sufu, a traditional Chinese fermented soybean curd, was prepared by ripening the salted pehtze in dressing mixture containing soy whey left over from making tofu. The biochemical and physical changes during grey sufu manufacturing were investigated. It was found that amino nitrogen, water-soluble protein, peptide and free amino acid content increased significantly during manufacturing. Meanwhile, hydrophobic amino acid proportion increased to 84.15% after ripening for 90 days. Examining the changes in short-chain fatty acids revealed that butyric acid, acetic acid and succinate increased, while lactic acid content experienced a significant decline. In addition, it was found that grey sufu was rich in butyric acid with the highest content of 25.44 mg/g dry matter, which was much higher than that of other foods known. It was suggested that high concentration of butyric acid might make grey sufu potentially helpful in controlling several diseases.

In this work, the influence of some reactional parameters in the hydrolysis of whey protein concentrate (WPC) was evaluated, in terms of the nutritional quality of peptide profiles of the hydrolysates as well as the reduction of costs for scaling-up the process. Two enzymes (subtilisin and pancreatin) were used for preparing 18 hydrolysates, using different E:S ratios and reaction times, and the distribution of peptides according to chain length was analyzed by size-exclusion chromatography. The studied parameters affected the peptide profiles of WPC hydrolysates and the best result was similar for subtilisin and pancreatin, both using an E:S ratio of 4:100, after 5 h and 10 h, respectively. In these conditions, these enzymes gave rise to the smallest large peptide contents (12.28% and 12.34%, respectively) and one of the highest amount of di- and tripeptides (13.34% and 13.00%, respectively) as well as of free amino acids (45.56% and 47.26%, respectively). However, in terms of number of samples the action of pancreatin was more advantageous than subtilisin, since among the nine hydrolysates, four showed appropriate peptide profiles (P1, P2, P5, and P6), from the nutritional point of view, while the same happened only with one hydrolysate prepared by using subtilisin (S3). Also, the economical advantage of using smaller E:S ratio and reaction time was observed in several cases for both enzymes.

The effects on microbiological parameters of minimally pasteurized cloudy apple juice concentrate obtained in a pilot scale from two apple varieties, and their changes with storage time and temperature were investigated. The juice obtained from Red Delicious apples showed an adequate biological stability for import and export market for storage at −8.5 and −20°C during a period of three months. The preservation of samples at −20 and −8.5°C limited to acceptable values the growth of molds and yeasts during the first two months in the case of juice obtained from Granny Smith apples. Neither lactic acid nor thermo acidophilic bacteria were isolated from the samples in all storage conditions. No noticeable differences in pH and soluble solids content were observed among storage times and temperatures. Turbidity increased slightly with storage time. Viscosity decreased substantially during storage at 2°C. Color was stable for all storage conditions evaluated.

The thin layer drying behaviour of tomato slices dried using microwave power densities of 1.13, 2.08 and 3.11 W/g combined with air ventilation (50°C) and hot air drying at 40, 50, 70 and 80°C was investigated. The tomato slice dried faster when subjected to microwave heating coupled with hot air ventilation. Drying time decreased considerably with increase in microwave power density and with increase in hot air temperature. Drying took place in a constant rate period followed by the falling rate period after a short heating period. The drying data were fitted to Newton (Lewis), Page, Henderson and Pabis, Logarithmic, Wang and Singh and Parabolic equations. The Parabolic model ( R 2 = 0.9999; χ 2 = 0.0085; MBE = 0.0182 and RMSE = 0.0691) gave the best fit to predict the hot air ventilation drying of tomato slices while the Logarithmic model ( R 2 = 0.9951; χ 2 = 0.0024; MBE = −0.0319 and RMSE = 0.0477) gave the best fit for microwave-assisted hot air drying of tomato slices. The values of the effective diffusivity coefficients of the tomato slices varied between 1.68 × 10 –9 and 5.22 × 10 –8 m 2 /s while the activation energy was 27.09 kJ/mol. The lower activation energy indicates that drying of tomato slices requires less energy and is hence a cost and energy-saving method. Microwave drying at 1.13 and 2.08 W/g maintained superior colour quality of the tomato slices.

Lotus ( Nelumbo nucifera Gaertn.) seeds were dried in a laboratory quality microwave oven to determine the effects of microwave output and mass load on drying time and drying rate. By increasing the microwave output power (231–539 W) and mass load (100–200 g), the drying time decreased from 36 to 13 min and increased from 18 to 30 min, respectively. The drying process can be divided into three stages: the heating period, constant rate period, and falling rate phase. A kinetics model which could describe the relationship of moisture ratio and drying time was established based on experimental data. The results show the drying procedure of lotus seeds could accurately be described by the Page model. The predicted values of the model were nearly consistent with the observed values. The moisture content and drying rate during the drying procedure matched the predicted results estimated by the Page model.

Explosion puffing drying was investigated as potential means for drying winter jujube. The sample was dried by hot air to dehydrate some amount of internal free water prior to explosion puffing drying to final moisture of less than 7% (wet bases). Physical properties (shrinkage, color, porosity, density, texture, and rehydration ratio) of crispy winter jujube dried by this method were evaluated and compared with those dried by convectional hot air drying alone, freeze-drying alone, combination of freezing drying and hot air drying, respectively. The comparison showed that crispy winter jujube dried by this method exhibited very close rehydration capacity, texture, density, porosity with those of the combination of freeze-drying and hot air drying. The sample dried by this method showed the more attractive crispness than those dried by freeze-drying and convectional hot air drying.

Investigation of qualitative indices for the pulsed microwave dried figs ( Ficus carica L.) is accomplished through image processing techniques. Three hundred colour pictures of fig fruit before and after drying were prepared in RGB colour space. After converting the RGB colour space into L a b units, colour values in L a b units were analysed before and after drying at five levels of microwave power intensity and six pulsing ratio levels. Kinetic parameters for the colour change were determined using the total colour change parameter, chroma, hue angle and browning index. The results showed that the L value decreases with the pulsing ratio and increases with microwave power intensity while a values remains constant with the microwave power intensity. Values of hue angle for dried fig varied between 1.21 and 1.32 radian, i.e. the dried fruits presented an appealing yellow/orange colour. Additionally, increasing microwave power intensity led to higher browning indices. Based on the resulting values, an optimized microwave drying of fig will be achieved serving as a tool for enhanced economical processing of the fruit.

To correlate the mechanical properties with the crumb structure of bread, a simple and objective method of measuring air bubbles of crumb samples was developed using an image scanner and digital image processing. Four images of the sample scanned in four orthogonal directions were aligned and combined to obtain an enhanced image in which air bubble regions were emphasized by min-operation, selecting the minimum gray level among the four images for each pixel. Next, Otsu’s method was applied to threshold each sub-image of the enhanced image in order to quantify the geometries of the air bubbles precisely, and then the black regions of the image were found to be air-bubbles. As a result, the four air-bubble parameters of the bread samples were determined to be mean bubble area, mean bubble perimeter, number of bubbles, and bubble area ratio. In addition, the viscoelastic properties of the samples were measured by the creep test and determined to significantly correlate with the bubble area ratio ( r > 0.59, p < 0.05). This indicates that with increasing air-bubble area, crumb hardness increases. The proposed method is inexpensive and easy to operate, and thus is considered to be applicable to the quality assessment in food factories.

In this work, we present a method for estimating the diffusion coefficient in isothermal drying processes in those cases in which the associated shrinkage cannot be neglected. We assume that the drying process is described by the diffusion equation and depart of a numerical solution of reduced order to the corresponding problem. The method chosen for identifying the parameter in question is based in a high gain filter. As an example for showing the proposed method we take a solid presented by Aguerre et al. ( Latin American Applied Research 2008;38:345–9). First, we solve the direct problem for generating an average moisture content profile and the corresponding radius profile. Taking the radius evolution as known data and the average moisture evolution as the innovation term in the filter, we solve the inverse problem and as a result a moisture-dependent diffusion coefficient is obtained, which is refined in a posterior and final optimization step.

The temperature profile and water absorption of chicken carcasses during the chilling process by immersion was investigated. The experiments were realized in a slaughterhouse that uses a pre-chiller and chiller operating by the immersion–rotation system in counter flow. Temperature gradients, in the entrance of the coolers, were higher in the pre-chiller than in the chiller, and the rates of heat exchange decreased as the carcass moves forward in each cooler. The influence of the immersion time (18, 22, and 27 min), period interval of ice addition (3 and 5 min) and the number of turbines used in the injection of air (1 or 2) on the temperature of carcasses leaving the pre-chiller was evaluated through a factorial design. The results indicated that the immersion time and the number of turbines were significant factors influencing the final temperature of the carcasses. Interactions among the time interval to ice addition with the time of immersion and this last with the number of turbines were also significant. The percentages of water absorption in the pre-chiller were between 2.0 and 4.5%. The best conditions were: 27 min for immersion time, 5 min time interval to ice addition, and injection of air through two turbines, which corresponded to 14.6°C and 4.1% of water absorption. In this condition, the temperature and water absorption of the carcasses leaving the chiller were 5.4°C and 6.8%, respectively. Refrigeration of poultry carcasses is one of the most important factors to reduce the growth of spoilage microorganisms and prolongs the shelf life of the product. Investigation of optimal conditions for chilling carcasses is an aspect of utmost relevance for meat quality.

In this study, some physical properties such as bulk density, true density, porosity and static coefficient of friction in four levels of moisture content (against four structural surfaces) of an Iranian commercial variety of hazelnut (Azarbayejani Hazelnut) and its kernel was determined. Bulk density increased from 409.7 to 491.4 kg m −3 and from 415.4 to 477.9 kg m −3 for whole nut and its kernel respectively. True density increased from 954.8 to 1079.4 kg m −3 for whole nut and from 886.9 to 965.8 kg m −3 for its kernel, porosity decreased from 57.11 to 54.47 kg m −3 and from 53.52 to 52.51 kg m −3 for whole nut and its kernel. The static coefficient of friction of both nuts and kernels on all four test surfaces increased with increasing the moisture content. The average friction coefficient (both nut and kernel) was the highest on MDF and the lowest on galvanized iron sheet.

The purpose of this work was to determine the levels of protein and the amino acid distribution in the cell mass of yeast strains ( Saccharomyces sensu stricto ) originated from Brazilian bioethanol industries. The protein was analyzed with the Kjeldahl method and the amino acids, by using high-performance liquid chromatography (HPLC). The percentages of the protein found ranged from 39 to 49%. The results show that in spite of some variation in numbers between the different yeast strains, all of them presented an amino acid profile similar to the one in the literature for S. cerevisae . The amino acids that have occurred in the largest amounts were: aspartic, glutamic acids and lysine, and those in the lowest amounts were: cysteine and methionine. Although the characteristics of the feedstock used and the process conditions are determinant of the protein values obtained in dry mass, this work elucidates that the intrinsic properties of the yeast strain influence these values.