Abstract: This study is a contribution to knowledge the color loss of pineapple slices during hot air drying process. The kinetics of color degradation of pineapple (Ananas cosmosus) slices were investigated at 40-60°C and at two drying principles: parallel airflow and traversing airflow. Those temperatures are in the range used to dry the commercial pineapple in tropical humid zone. Color changes associated with heat-treated slice were monitored using Hunter colorimeter (L, a, b, total color difference ΔE). The results showed that temperature had a significant effect on the color loss of pineapple slice during the process. At 60°C the color loss is less perceptible. The parallel flow drying process permits us to obtain high color quality during thermal process.

Abstract: The chemical and microbiological quality and safety of fresh fish obtained from the retail and supermarkets of Sri Lanka were examined. Fresh fish samples (n = 155) of yellowfin tuna (Thunnus albacares), sailfish (Istiophorus platypterus), salaya/ sardine (Sardinella gibbosa, shrimp (Fenneropenaeus indicus) and squids sp (Loligo duvaucelii) were collected from 19 places around the country and evaluated in the laboratory. Samples were analysed for several chemical and microbial quality including total volatile base nitrogen, histamine, total mercury and total plate count. Furthermore, the presence of selected pathogens such as Escherichia coli and Salmonella spp. were detected. In microbiological analysis of samples total plate counts were obtained in the range of 7 x 10³-1.2 x 10⁸ cfu/g and 28% of the samples had < 5 x 10⁵ cfu/g. Eight percent of the samples contained > 10³ MPN/g of E. coli and 1 sample contained 500 MPN/g and rest of the samples had < 200 MPN/g with 33% of the samples without E. coli. Twelve percent of samples were positive for Salmonella spp. The range of total volatile base nitrogen (TVB-N) was 15-4883 mgN/100 g and 33% samples were exceeded the maximum acceptable levels. Further considering histamine and mercury level of yellowfin tuna and sailfish, 7% and 4% of samples exceeded the maximum acceptable levels respectively. When considering both microbiological and chemical results it can be seen that majority of the samples are not fit for the human consumption and that counted as; 35% of yellowfin tuna, 47% of sailfish, 35% of sardine, 100% of squids and 53% shrimp.

Abstract: Elephant foot yam was dried under different microwave power ranging from 180 W to 900 W and sample thickness (5-15 mm) to study their effect on microwave drying kinetics. Drying time, drying rate, kinetic rate constant, effective moisture diffusivity and rehydration ratio are various factors studied. Increase in microwave power and decrease in sample thickness increased drying rate and decrease the drying time. The Fick’s diffusion method was also used to model the experimental data. The effective moisture diffusivity values were found to be in the drying conditions range of 4.44 x 10-9 m²/s to 1.17 x 10-7 m²/s. The modified Arrhenius type equation was used to calculate the activation and the resulting range was from 23.47 to 9.23 Wg-1 for varying thickness of the sample. On the other hand, the interaction effect of drying conditions on the average drying rate, drying time, drying rate constant and effective moisture diffusivity with high significance has been explained by the second order quadratic polynomial model.

Abstract: The objective of this study was to extract yellow pigment from powder turmeric (Curcuma longa) rhizomes and to evaluate the preservative/antioxidant activity of oil-soluble yellow pigment at concentrations 0.5, 0.1 and 0.2% (w/w) in soybean oil after accelerated oxidation at for 7 days. Soy bean oil free from antioxidant (control) and with 0.02% butylated hydroxytoluene (BHT) (synthetic antioxidant) were used to control. In addition, the effects of combined treatment of water-soluble yellow pigment at ratio 3% (w/w) and gamma irradiation at dose levels of 1, 3 and 5 kGy on the microbiological, chemical and sensory characteristics of chicken breast fillet samples during cold storage (4 ± ) to extend the shelf-life of chicken breast fillets were investigated. The results revealed that the addition of 0.2% oil-soluble yellow pigment caused detectable increments in the oxidative stability of soy bean oil compared with control and other treatments under investigation. The results showed that the ratio of 3% of water-soluble yellow pigment reduced the total bacterial count, Psychrophilic bacteria, lactic acid bacteria, enterobacteriaceae, total molds and yeasts, Staphylococcus aureus, Bacillus cereus, Enterococccus faecalis and Salmonella spp, was not detected in all treated samples. Also, shelf-life periods were increased up to 39 days for chicken breast fillet samples treated by 3% water-soluble yellow pigment and gamma radiation at dose level of 5 kGy. Thus, these results illustrate that yellow pigment extracted from turmeric rhizomes exhibit strong antioxidant and antimicrobial activities. Therefore the use of these yellow pigment extracts in food is recommended to suppress lipid oxidation and may be useful as natural food colorant and preservative and an alternative to synthetic dyes that are harmful to health.

Abstract: Vegetable and fruit derived fibre plays a crucial role in promoting good health. Soluble and insoluble fiber has different physiological roles in human body. Insoluble fiber is known for having several beneficial effects like anti-constipating, hypoglycemic, hypocholesterolemic. In the present study, insoluble dietary fiber from vegetables viz., Nelumbo nucifera, Murraya koenigii, Abelmoschus esculentus and Brassica oleracea were investigated in vitro for their hypoglycemic and hypocholesterolemic effect. The hypoglycemic effect was studied by measuring glucose adsorption, glucose diffusion and amylase inhibitory activity whereas hypocholesterolemic effect was observed by bile salt (Sodium cholate) adsorption study. Results indicate that N. nucifera exerts significanteffect on glucose adsorption (7.40 ± 0.14 mmol/g) and amylase inhibitory activity (13.19 ± 0.66 %). Similarly glucose diffusion studies showed low diffusion values in case of N. nucifera as compared to others up to an hour. Also, N. nucifera showed highest sodium cholate binding capacity (10.11 ± 0.20 %) compared to other fibres when cellulose was used as a control. Thus, this study suggests that insoluble fibre from N. nucifera can be used for fortification of functional food products aimed at controlling glucose and cholesterol level.