Background Evidence of chronic low levels of exposure to heavy metals in Sri Lanka has emerged in a number of studies carried out in the recent past. The source and magnitude of such exposures have to be understood in order to assess the risk of adverse health effects of this exposure and to propose suitable public health interventions. Methods An assessment was carried out to quantify chronic exposure to cadmium, lead and arsenic through food in people living in an area in Sri Lanka, where prevalence of Chronic Kidney Disease of unknown origin (CKDu) is highest. First a dietary survey was carried out in the subjects to estimate the type and quantity of typical food items in order to estimate an average consumption. A model diet was formulated using this dietary consumption data; and this was thereafter used for estimation of chronic dietary exposure of selected contaminants. In parallel, the levels of contaminants of interest in the various identified food items: cadmium, lead and arsenic, were determined. Results Assuming the major route of intake is food, and based on the quantity and type of food items consumed, a 60 kg man is exposed to average doses of 83.7 μg cadmium, 924.1 μg lead, and 180.3 μg arsenic per week. The impact of chronic lead exposure was affirmed by a mean blood lead level of 3.0 μg/dL, with a maximum level of 8.8 μg/dL being observed in some cases. Conclusions Chronic low dose exposure of lead from food appears to be a public health concern in the studied population. Cadmium exposure through food appears to be of concern also. However, arsenic exposure through food appears to be within safe limits. As there are numbers of possible adverse health outcomes that can be associated with such estimated exposures of heavy metals, public health interventions are warranted to limit the described harmful exposures. Advocacy on dietary patterns and agronomic practices to lower the contaminants identified are the two broad strategies suggested.

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Coconut water is a highly nutritious liquid food which is a by-product of the desiccated coconut industry. Freeze concentration is the most suitable concentration method for coconut water since the low-temperature operation for concentration does not deteriorate the original quality of coconut water. Suspension freeze concentration (SFC) and progressive freeze concentration (PFC) are the available FC methods, and SFC is a complex and expensive method compared with PFC. PFC is a novel freeze concentration technique to concentrate liquid food by using a simple system. The limitation of PFC is the lower product yield than SFC, and to overcome the problem, the partial ice-melting technique can be used. A simple cylindrical apparatus was used for PFC which consists of a sample vessel, agitator system, and a cooling bath (at −23°C±2°C temperature). The final concentration of the liquid product was directly affected by the apparatus agitator speed and sample vessel dipping speed. PFC agitator speed of 290 rpm and dipping speed of 1.3 cm h-1 were reported as the optimum operating conditions to achieve the highest concentration for the PFC apparatus used in this study. Using optimized agitation speed and dipping speed, coconut water was concentrated up to Brix 8.5° from the initial concentration of Brix 3.5°. PFC coconut water achieved 73.56% of total yield, 2.42 of concentration ratio, 0.7° of ice phase concentration, and 0.08 of effective partition coefficient. The partial melting technique was successfully explored by recovering initial ice fractions with high solute concentrations, and the total yield was improved up to 80%.

The research focused on processing palmyrah fruit pulp into a value added product to broaden the utilization of palmyrah fruit pulp. Set, swiss style, jelly and pulp preserve yoghurts incorporated with palmyrah fruit pulp were developed. Control yoghurt and plain yoghurt for other preparations were prepared with 13 % sugar, 1% gelatin, 12 % skim milk powder and lactic acid bacteria culture following household method. The fresh pulp was kept at-25 oC for 48 hours and heated up to 85 oC for 30 minutes with 5 % cane sugar, 0.6 % tartaric acid, 1 % ascorbic acid and 0.13 % sodium chloride. The treated pulp was added at 5 %, 7.5 %, 10 %, 12.5 % and 15 % into both set and swiss style yoghurts. Fruit jelly was prepared with sugar, gelatin, sodium citrate, citric acid and 20 % pulp. It was then incorporated into yoghurt at 5 % and 6 %. Palmyrah fruit pulp preserve was prepared by heating sugar, pectin and pulp (45. 8 %) until its brix reached 68.5 o and it was topped on set yoghurt at 5 %, 7.5 % and 10 %. Sensory evaluation for colour, odour, appearance, mouth feel and texture was conducted with 21 untrained panelists using 5 point hedonic scale and the optimized pulp concentrations for set, swiss style, jelly and preserve yoghurt were 5 %, 7.5 %, 6 % and 10 % respectively (p < 0.05). The overall sensory qualities of all palmyrah fruit yoghurts were rated as good to very good. There were no significant changes in sensory attributes, brix and pH in storage at 4 oC. Shelf life was 18 days for all products at 4 oC without any preservatives except set yoghurt as it showed separation of water from the third day of the preparation. Nutritional and microbiological qualities of the products were investigated and compared with control yoghurt. Protein was higher in swiss style (6.12 %) and jelly (7.77 %) yoghurts. Carbohydrate was higher in swiss style yoghurt (36.87 %) and preserve yoghurt contained highest fat content (2.57 %).