Flavor and Stability of "Horchata De Chufas"

Horchata is a sweetened water extract of chufa tubers (Cyperus esculentus) which is very popular in Spain, and has potential in the U.S. The objectives of this research were to characterize horchatas from different types of chufa, and to monitor flavor and stability of unheated and pasteurized horchatas during storage (2°C). Trained panelists rated the following attributes: color, chalkiness, sweetness, vanilla-like, nutty, earthiness, bitterness, and off-flavor. Horchatas made with chufa grown in Spain and chufa from Spain but grown in Florida showed higher vanilla and nutty levels than horchata from the Florida type. During storage (2°C), vanilla, nutty, and sweetness decreased, and other attributes increased. Heating to 70 and 95°C for 1 min did not alter sensory attributes initially, prevented off-flavor development, and slowed changes in desirable attributes for 35 days.     

DRAG ON MULTIPLE SPHERE ASSEMBLIES SUSPENDED IN NON-NEWTONIAN TUBE FLOW

The drag forces experienced by single and multiple sphere assemblies suspended in non-Newtonian tube-flow were investigated under different levels of fluid viscosity of aqueous CMC solutions (m=2.0 to 21.1 Pa-sⁿ and n=0.73 to 0.82), flow rate (0.02 to 0.86 kg/s) and particle concentrations (1.53 to 11.01% on a volume basis). It was found that an increase in particle concentration resulted in an increase in drag force experienced by each sphere in an assembly. It was also observed that the presence of identical assemblies upstream and downstream of the single test assembly (multiple assembly case), resulted in drag force increases per sphere from 14% for low concentration to 25% for high concentration. an equation was developed to predict a drag correction factor for Stokes' equation for the multiple assembly configuration based on particle concentration.     

RHEOLOGICAL CHARACTERIZATION of COFFEE MUCILAGE

Rheological behavior of mucilage obtained from two varieties of coffee grown in Colombia (Caturra and Colombia) was studied as a function of ripe cherry content (RCC) and postharvest time (PHT). A Brookfleld HB DV-III viscometer was used in concentric cylinder geometry over a shear rate range of 4.8 to 120 s⁻¹. the power-law model was used to describe the shear stress versus shear rate data, and the consistency index (K) and flow behavior index (n) were determined. the mucilage is a highly viscous and pseudoplastic (n < 0.3) fluid. the K increased and n decreased as the RCC and PHT increased. the mucilage of the Caturra variety was more viscous and shear thinning than that of the Colombia variety. Microstructural examination of the mucilage revealed that certain weak structures as phloem vessels found in the mucilage may be destroyed upon application of shear stress and may contribute to the pseudoplastic nature of the mucilage. Diffusion of tannin from the pulp to mucilage with delay in postharvest processing may be responsible for increased apparent viscosity with increased PHT.     

POTENTIAL TOXICITY OF PYOVERDIN FROM PSEUDOMONAS ON MOUSE LIVER

Pseudomonas fluorescens were isolated from food and water. Bacterial strains were grown on synthetic medium and pyoverdin was purified with Fe³⁺. Iron was removed from some samples with 8-hydroxyquinoline to obtain free-pyoverdin. Purification was performed by chloroform/phenol, diethylether/water extractions, column chromatography and silica gel slabs. Mice were given water with pigment for prolonged periods to study the chronic effect on liver. Alanine amino transferase (ALT) and Aspartate amino transferase (AST) increased significantly in animals treated with pyoverdin-Fe, free-pyoverdin and heated pyoverdin. Sex dependence was not observed. The effect on hepatic enzymes was also studied employing chromatographic peaks separately and mixed. Analyses of variance for statistical evaluation was applied. Controls treated withpyoverdin-negative culture extract did not show amino transferase's increase. It was found that prolonged ingestion of pyoverdin can affect hepatic enzymes in mice.     

APPLICATION OF CORRELATION BETWEEN BIOT AND DINCER NUMBERS FOR DETERMINING MOISTURE TRANSFER PARAMETERS DURING THE AIR DRYING OF COROBA SLICES

The moisture mass transfer parameters characterizing the air drying of coroba slices were determined using the correlation between Biot and Dincet numbers. The air drying was carried out at temperatures of 71, 82 and 93C and velocities of 0.82, 1.00 and 1.18 m/s. Experimental moisture content data for coroba slices were collected. The drying coefficient and lag factor were calculated from the experimental data and were incorporated into the correlation. The moisture diffusion coefficient, Biot number and mass transfer coefficient ranged between 1.147  ×  10 ^{− 12} –3.740  ×  10 ^{− 12}  m²/s, 0.097–0.114 and 0.903  ×  10 ^{− 4} –1.729  ×  10 ^{− 4}  m/s, respectively. The predicted dimensionless moisture content profiles showed adequate agreement with the experimental observations, with the mean relative error between 0.98 and 4.61%.

PRACTICAL APPLICATION

As drying is an energy-intensive operation, it has become the prime concern of the researchers to optimize process conditions that lead to energy savings. Moisture transfer parameters are important transport properties needed for accurate modeling in food drying applications. Therefore, accurate determination of these parameters for the drying operation is essential. There is a large amount of studies available in the literature to determine and calculate these parameters for the products subjected to drying. But limited studies have been carried out to determine these parameters using the drying process parameters in terms of lag factor and drying coefficient as first introduced by Dincer and Dost.     

EDIBLE COATINGS ON FRESH SQUASH SLICES: EFFECT OF FILM DRYING TEMPERATURE ON THE NUTRITIONAL AND MICROBIOLOGICAL QUALITY

The exposure of foods to the temperature and humidity needed to dry the coatings can have deleterious effects on their quality. A critical analysis of the film drying conditions on quality indexes for butternut squash slices is presented. During the coatings drying, the samples lost significant amounts of weight and ascorbic acid. Only during the drying of the chitosan coating for 100 min at 20C and for 30 min at 50C that the ascorbic acid contents were not significantly reduced. The application of casein and carboxy methyl cellulose coatings did not cause significant reductions in the counts of mesophilic aerobic microorganisms (5.75–6.00 Log CFU/g). Chitosan coated samples presented significant log reductions showing the higher reductions the samples dried for 30 min at 50C (5.02 Log CFU/g). For the preservation of the nutritional and microbiological quality indexes of squash slices, the best coating conditions would be chitosan dried for 30 min at 50C.

PRACTICAL APPLICATIONS

The continuous consumer interest in high quality and food safety, combined with environmental concern, has induced the development and study of new edible coatings that avoid the use of synthetic materials. The edible coatings, formed from Generally Recognized as Safe materials, have the potential to reduce weight loss, respiration rate and improve food appearance and integrity. It is one of the most effective methods to maintain food quality.
Antimicrobial films and coatings have innovated the concept of active packaging and have been developed to reduce, inhibit or delay the growth of microorganisms on the surface of food in contact with the packaged products. In addition, the edible coatings allow the incorporation of food additives with antimicrobial effects that might help reduce microbial spoilage during postharvest.     

Viscosity of Molten Milk Chocolate with Lactose from Spray-Dried Whole-Milk Powders

Dry whole-milk powders containing 0, 30, 50 and 70% nominal lactose prepared by spray-drying alone, or followed by post-drying crystallization, were incorporated into milk chocolate to give 0–50% substitution of lactose for sucrose. Increasing the concentration of amorphous lactose from spray-dried powders in the chocolates decreased viscosity, increased particle size of refined chocolate mass, and lowered the concentration of surface-active agents at which a minimum in Casson yield value was observed. Increasing the concentration of crystalline lactose from milk powders in the chocolates increased viscosity, decreased particle size, and increased the concentration of surface-active agents at which a minimum in Casson yield value was observed. Conditions which affect lactose crystallinity in milk powders, such as improper storage and handling prior to use in chocolate production, could be responsible for variations in chocolate viscosity noted sometimes by processors.     

A REVIEW of PARTICLE BEHAVIOR IN TUBE FLOW: APPLICATIONS to ASEPTIC PROCESSING1

The design of holding tubes for continuous sterilization of foods containing large particulates depends heavily on knowledge of pipe flow behavior of food suspensions. Although directly related literature is limited, a considerable body of potentially useful literature is available on solid-liquid flows. This critical review discusses literature on solid-liquid flow in tubes, including capsule flow, effects on bends, radial migration phenomena, particle-particle interactions, modeling studies and other topics which may have a bearing on particle velocities in holding tubes.