Food Science and Technology International current issue

Review. Freeze Concentration in the Fruit Juices Industry

Sanchez, J., Ruiz, Y., Auleda, J.M., Hernandez, E., Raventos, M. — Wed, 04 Nov 2009 09:16:38 PST

In conventional processes, such as evaporation, higher levels of concentration can be reached compared with freeze concentration or membrane techniques. However, the advantage of the freeze concentration technique is based on the quality of the product obtained due to the low temperatures used in the process, which makes it a very suitable technology for the processing of fruit juices. There are two basic methods for concentrating solutions by freezing: suspension and film freeze concentration. Suspension freeze concentration systems (FCS) already have operating equipment in the food industry, while film FCSs, also called layer crystallization, is still at an experimental stage. This review summarizes the most important studies relating to the suspension and film freeze concentration in fruit juices and sugar solutions, illustrating the different possibilities that freeze concentration has in the fruit juices industry; it also presents trends and suggests improvements for the future development of this technology. It is noted that most recent publications refer to the film FCS. The technology used to design, build and maintain layer crystallization equipment is simple and it can be available to any operator in the food industry, layer systems will be used in the future if their results can be improved in terms of ice purity and degree of fluid concentration.

Inulin Addition in Starch-based Dairy Desserts: Instrumental Texture and Sensory Aspects

Lobato, L.P., Grossmann, M.V.E., Benassi, M.T. — Wed, 04 Nov 2009 09:16:38 PST

Interactions between ingredients have a wide application in the food industry. The objective of this work was to investigate the combined effect of milk, starch, and inulin on textural properties (firmness, gumminess, cohesiveness, and adhesiveness), syneresis, and sensory characteristics of pudding (by free-choice profile (FCP) and acceptability test), applying the experimental design for mixtures. Milk and starch were significant for all the studied texture parameters. Milk, inulin, and the interaction of the inulin with starch were significant for syneresis. It was possible to formulate pudding with the maximum inulin concentration (3.9%) with good textural characteristics. The judges were capable of distinguishing attribute differences and similarities, mainly in relation to texture, by applying the FCP. In the acceptance test, the judges concluded that there are no differences (p < 0.05) among the tested formulations. The different proportions among ingredients in the system can affect the characteristics of the final product. Inulin inclusion in pudding, as a functional ingredient, was successful.

Effect of Raisin Juice Addition on Bread Produced from Different Wheat Cultivars

Sabanis, D., Soukoulis, C., Tzia, C. — Wed, 04 Nov 2009 09:16:38 PST

Concentrated and two types of dried raisin juice were added to bread and durum wheat flour dough at 50% level of sucrose substitution to prepare different bread samples. Baking (specific volume, color, crumb moisture, sensory evaluation), textural properties, and dough rheological properties were determined in breads. Results suggested that Greek durum wheat flour was appropriate for breadmaking and contributed to the baking, sensory, and textural properties of the final product. Addition of concentrated raisin juice in dough products both as a sucrose substitute and natural colorant gave breads with a higher loaf volume, fruity flavor, and an appealing brown color. Breads containing dried raisin juice were sensory rated lower than those with sucrose, however, they improved loaf volume and increased preservation time. This study also examined statistically the relationship between sensory responses and instrumental measurements, which is of major importance in the food industry for various applications.

Nutritional Effects of Mechanically Deboned Chicken Meat and Soybean Proteins Cross-linking by Microbial Transglutaminase

Wed, 04 Nov 2009 09:16:38 PST

This work studied the nutritional effects of protein cross-linking as mediated by microbial transglutaminase (TGase) using rats as biological models. Rats were divided into six groups that received diets containing casein (standard protein diet), cross-linked meat protein (CMP), meat protein (MP), cross-linked soy protein, or soy protein (SP) as the protein sources of their diets, which were compared against an aproteic diet (basal diet). The cross-linking process showed a significant (p < 0.05) impact on the true digestibility (TD) of meat and SPs, decreasing it for the first and increasing it for the second. As a consequence, the TD of modified SP became similar to that observed for CMP, although, the biological value, net protein utilization, net protein ratio, and protein retention efficiency values of meat and SPs were not affected in the process. These results suggest that the use of TGase for the reticulation of isolated SP can improve its nutritional quality.

The Effect of Cooking in a Steam-convection Oven and Storage in Vacuum on the Quality of Turkey Meat

Wed, 04 Nov 2009 09:16:38 PST

The effect of cooking on the quality of turkey meat heated by steam at different temperatures and saturation levels, and then vacuum stored at 3 °C for 28 days, was studied. The smallest cooking loss was observed in meat cooked at 220 °C and when the highest air steam saturation was applied. The rate of lipid oxidation as a result of cooking and storage was the lowest in sample cooked at 180 °C and in meat heated by 20% steam, and additionally during storage in sample treated with 0% steam. The higher cooking temperature was applied, the more intensive hydrolytic process took place in fat. Heating at 180 °C and in hot air with 0%, 70%, and 90% steam resulted in a more intensive hydrolytic process in meat during storage than other cooking parameters. The oxidation rate of -SH groups was higher in sample heated by 90% steam than the ones by 20%, 50%, and 70% steam. The use of steam saturation over 20% caused a decrease in mono-unsaturated fatty acids and an increase in saturated fatty acids content. Meat cooked at 220 °C and treated with 0% or 90% steam was characterized by better sensory attributes than other samples.

Effect of Sweeteners on Radical Formation in Starch Studied by Electron Paramagnetic Resonance Spectroscopy

Wed, 04 Nov 2009 09:16:38 PST

The process of radical generation occurring upon thermal treatment of potato and corn starch containing sweeteners: saccharose, acesulfam K, aspartame, and sorbitol was investigated by electron paramagnetic resonance spectroscopy, using Cu²⁺ ions as a paramagnetic probe. It was found that the influence of acesulfam K and sorbitol on radical formation is stronger than that of other additives. Acesulfam K increased the amount of radicals in the starch compared to native starch, whereas sorbitol significantly decreased their concentration. The influence of sweeteners on radical processes in the starch is because of differences in their molecular structures and presence or absence of OH groups.

Influence of Semicontinuous Processing on the Rheology and Droplet Size Distribution of Mayonnaise-like Emulsions

Bengoechea, C., Lopez, M.L., Cordobes, F., Guerrero, A. — Wed, 04 Nov 2009 09:16:38 PST

Oil-in-water (o/w) emulsions stabilized by egg yolk, with a composition similar to those found in commercial mayonnaises or salad dressings, were processed in a semicontinuous device. This specially designed emulsification device consists of, basically, a vessel provided with an anchor impeller, where the continuous phase was initially placed; a pumping system that controls the addition of the oily phase; a rotor-stator unit, where the major breaking of the oily droplets takes place, and a recirculation system. The design allowed the introduction of a rotational rheometer to obtain viscosity data along the emulsification process. The most important advantages of this in-line emulsification device, when compared to discontinuous emulsification equipment, are the possibilities of recording viscosity data along the process and the higher values for the storage, G', and loss moduli, G'', of the resulting emulsions. The influence of egg yolk concentration, agitation speed, and flow rate over the rheological properties (G', G'') as well as droplet size distribution were investigated. Higher protein concentration, agitation speed and flow rate generally produce emulsions with higher G' and G'' values.

Sensory Profile and Acceptability of Juices from Mandarin Varieties and Hybrids

Carbonell, L., Bayarri, S., Navarro, J.L., Carbonell, I., Izquierdo, L. — Wed, 04 Nov 2009 09:16:38 PST

Fresh juices from mandarin varieties, from hybrids, and from blends of these raw materials were evaluated by 100 consumers to determine acceptability, and by 10 trained panelists to quantify sensory attributes. Trained panelists found the juice from Clemenules richer in both mandarin and fresh flavor (odor and taste) whereas Nova juice presented minimum scores for these attributes. These aspects obviously affected the evaluation of acceptability by consumers, who preferred the juice from Clemenules (a Clementine variety) either alone or blended in major proportions with less preferred varieties such as Marisol, Hernandina (Clementines), Ortanique or Nova (hybrids). Nova juice was rejected by most consumers, but accepted by a small group of them. These results are of great importance for the European citrus industry since Clemenules is the most abundant variety and will constitute the main source of raw material for processing plants.

Chromatic Changes in Broccoli (Brassica oleracea italica) under Modified Atmospheres in Perforated Film Packages

Rai, D.R., Jha, S.N., Wanjari, O.D., Patil, R.T. — Wed, 04 Nov 2009 09:16:38 PST

Broccoli was stored under modified atmosphere packaging (MAP) at 20 °C in perforated and unsealed polypropylene film packages for a storage period of 10 days to evaluate the effect of modified atmospheres on the chromatic changes. At the end of storage, MAP resulted in differential changes in the original green color of broccoli under different packaging treatments. Instead of conventional CIELAB color space system utilizing only L*, a* and b* values, the chromatic changes were analyzed as per L*C*h* color space system using lightness, chroma, and hue angle values to evaluate the final hue (color) along with its associated attributes. On 10th day of storage, broccoli samples kept under different modified atmospheres were observed to be yellow-green only for 4 holes, but between yellow-green and yellow for 8, 12, and 16 hole treatments, respectively. Further, the saturation of final hue attained under different packaging treatments kept on increasing in the order of 4, 8, 12, and 16 holes. On the other hand, broccoli kept in air in unsealed packages turned orange-yellow with higher saturation as compared with MAP samples. The direction of color difference for different treatments with respect to fresh broccoli samples was observed as light and the degree of color difference indicated that 4 and 8 hole treatments were only slight and medium light, respectively. The 4 hole treatment had best color retention as it had slightly saturated yellow-green hue, which was only slightly lighter than the fresh broccoli. Also, the results of sensory and visual analysis confirmed the results obtained from L*C*h* color space diagram and indicated that the modified atmosphere (6.1% O₂ and 9% CO₂) generated inside the perforated film packages having 4 macro-holes was the most suitable in maintaining the chromatic quality of the broccoli heads.

Intermittent Microwave-convective Air Drying of Oregano

Soysal, Y., Arslan, M., Keskin, M. — Wed, 04 Nov 2009 09:16:38 PST

Effectiveness of intermittent microwave-convective air drying (IMWC) was investigated and compared to continuous microwave-convective air drying (CMWC) and convective air drying for oregano. Both CMWC and IMWC increased the drying rate of oregano compared to convective drying. The CMWC and IMWC were 12.7-14.0 and 4.7-11.2 times more energy efficient in drying than convective drying, respectively. The highest essential oil contents were obtained from convective drying at 40 °C and 45 °C. However, these treatments had the longest drying time and the highest energy consumption. The CMWC yielded the lowest essential oil content and resulted in an extreme change in the essential oil composition. The IMWC, except with the pulse ratio of 3.0, resulted in similar essential oil content compared to convective drying at 50 °C and shade drying. No identical result was found among the prevailing compounds of essential oil of oregano obtained from shade drying, convective drying and IMWC. Both CMWC and IMWC did not yield acceptable results of product color. However, in terms of essential oil content and quality, the IMWC at 25 °C room temperature with the pulse ratio of 5.0 was judged as the most suitable drying method for oregano due to its rational drying time and energy consumption compared to CMWC drying, convective air dying, and shade drying.

Microcapsules of a Casein Hydrolysate: Production, Characterization, and Application in Protein Bars

Rocha, G.A., Trindade, M.A., Netto, F.M., Favaro-Trindade, C.S. — Wed, 04 Nov 2009 09:16:38 PST

The aim of this work was to encapsulate a casein hydrolysate by spray drying using maltodextrins (DE 10 and 20) as wall materials and to evaluate the efficiency of the microencapsulation in attenuating the bitter taste of the hydrolysate using protein bars as the model system. Microcapsules were evaluated for morphology (SEM), particle size, hygroscopicity, solubility, thermal behavior (DSC), and bitter taste with a trained sensory panel by a paired comparison test (nonencapsulated samples vs. encapsulated samples). Bars were prepared with the addition of 3% casein hydrolysate at free or both encapsulated forms, and were then evaluated for their moisture, water activity (a_w) and for their bitter taste by a ranking test. Microcapsules were of the matrix type, having continuous surfaces with no apparent porosity for both coatings. Both encapsulated casein hydrolysates had similar hygroscopicity, and lower values than free encapsulated hydrolysates. The degree of hydrolysis of the maltodextrin influenced only the particle size and T_g. The sensory panel considered the protein bars produced with both encapsulated materials less bitter (p < 0.05) than those produced with the free casein hydrolysates. Microencapsulation by spray drying with maltodextrin DE 10 and 20 was successful to attenuate the bitter taste and the hygroscopicity of casein hydrolysates.