Journal Title :  Journal of Technology and Value Addition

Volume : 2 Issue : 2

Page  : 1 – 12

Submitted :  February 28,2020; Accepted: July9, 2020

Correspondence :  ranjith@uwu.ac.lk

In conventional instant black tea manufacture, tea extract is concentrated to about 25-40°Brix by thermal evaporation before spray drying. Most of the organoleptic properties of tea are destroyed at this stage. Therefore, potential of improving physicochemical and organoleptic properties of instant black tea by applying membrane-based pre-concentration technique was investigated. For membrane concentration of tea extract, a membrane was selected and operating temperature and pressure were optimized. A tea extract was prepared and a half of it was concentrated to about 12°Brix by membrane filtration technique using the selected membrane (250 Da) under optimized operating temperature (30°C) and pressure (25 bar). This pre-concentrated tea extract was further concentrated to 25°Brix by thermal evaporation and spray dried to instant black tea powder. Remaining half of the tea extract was concentrated to 25°Brix by thermal evaporation alone and it was spray dried to instant black tea powder under similar conditions. Physicochemical and sensory properties of these samples were evaluated. Theaflavin content, colour, and brightness of instant black tea prepared with the application of membrane-based pre-concentration technique (3.0±0.6 g/100 g, 3.3±0.2 and 17.2±4.0 respectively) were significantly (P<0.05) higher than those of control (1.7±0.2 g/100 g, 2.3±0.2, and 13.8±2.0 respectively). Furthermore, sensory properties; brightness, strength, and overall quality of instant black tea prepared with the application of membrane-based pre-concentration technique received more positive responses than those properties of control sample. Pre-concentration of tea extract using membrane filtration technique will improve physicochemical and organoleptic properties of instant black tea.

Keywords: Chemical properties, Instant black tea, Membrane filtration, Physical properties, Sensory properties

Journal Title : Journal of Technology and Value Addition

Volume : 2 Issue : 2

Page : 13 – 38

Submitted : February 28,2020; Accepted: July9, 2020

Correspondence : sunethuop@gmail.com

Rose apple (Syzygium spp.) is a preferred fruit type in tropical and subtropical regions. However, in Sri Lanka, rose apple is considered as an underutilized fruit, although it has many nutritional and medicinal values that can be exploited to make value-added products and export as fresh fruits. A limited emphasis has been made on the morphogenetic, organoleptic, and phytochemical variability of rose apple species grown in Sri Lanka, namely S. aqueum (SA), S. malaccense (SM) and S. samarangense (SS). Thus, we assessed the interspecies diversity and seasonal variation of fruit size, preference, and phytochemical content of these rose apple species using the fruits collected in 2018 and 2019 (Season 1 and 2 respectively). The Season 1 received higher rainfall thus could be considered as the wet season and the Season 2 was relatively drier. The dryness of the Season 2 caused the production of smaller fruits in SM and intense red coloration of the fruit skin in all three species and greenness in SM. The consumers prefer SA and SS fruits more than SM fruits. There was a variation of organoleptic preference found within species when two seasons compared. The fruit texture and skin color are the most critical parameters in deciding overall taste. The accumulations of anthocyanin, terpenoids, phlobatanins, and tannin are also enhanced by drier season. The seasonal difference features marked differences in the overall phytochemical profiles of the fruits in three species. The DNA barcoding marker, ITS4-5, clearly defines the species delimits and phylogenetic relationships with respect to the global Syzygium germplasm enabling the authentication of fruit type and value-added products in industrial applications. It is evident that the maintenance of a precise soil moisture regime is the key to produce high-quality rose apples for the export market and value-added products.

Keywords: Phylogenetics of Syzygium spp., Organoleptic values of rose apple, Sri Lankan fruits, Watery apple, Underutilized fruits

Journal Title : Journal of Technology and Value Addition

Volume : 2 Issue : 2

Page : 39 – 64

Submitted : July21, 2020; Accepted: August13, 2020

Correspondence : sandun@uwu.ac.lk

Sargassum crassifolium is an edible brown-seaweed which contains many bioactive compounds. The study was developed to extract crude proteins using four different methods and determine the functional properties. SDS-PAGE was used to analyze the extracts and best methods were selected. Accordingly, water (1:3), salt (4%), alkaline (1:3) and ethanol (1:4) extractions were selected as the best methods to extract crude protein from S. crassifolium. Among them, salt extract showed the highest protein content (p<0.05). Each treatment has shown low intensity band patterns.  Ethanol extract showed highest iron chelating and low oxidation levels. Salt extract showed higher DPPH activity while all extracts showed less antibacterial activity (p<0.05). Therefore, we can conclude that crude extracts from S. crassifolium showed effective free radical scavenging, metal chelating and low antibacterial activities. 

Keywords:Antibacterial, Antioxidant, Crude protein, Extraction, Metal chelating

Journal Title : Journal of Technology and Value Addition

Volume : 2 Issue : 2

Page : 65 – 84

Submitted : March18, 2020; Accepted: June30, 2020

Correspondence : indikau@uwu.ac.lk

Exotic Pterygoplichthys disjunctivus is an invasive fish and has established naturally recruiting populations in Sri Lankan reservoirs. P. disjunctivus is heavily caught into gill nets with mesh size >8.40 cm which has recommended for the inland fisheries in the country. However, small fish are rarely caught into this fishing gear. Present study was conducted with the objective of studying he efficiency of small meshed gill nets to catch immature stages of P. disjunctivus as a controlling measure of their populations in local water bodies. Similarly, it is important to know the impact of small meshed gill nets on commercial fish stocks and the local fish species living in reservoirs. Gill nets with mesh sizes 1.25, 2.5, 3.75, 5.0, 6.25, 7.5, 8.50 and 10.0 cm (length 20 m & height 2 m each) were used to sample fish species in four hourly intervals in Kalawewa and Victoria reservoirs during a period of 24 hours.Total number of sampling occasions for each reservoir was 24 (6 times per day*4 days) and total exposure time was 24 hours (one hour exposure time in one occasion). The total length was measured to the nearest 0.1 cm for each species. The total length measurements were analysed for the selectivity of gillnet. The optimum length for each mesh size for each fish species was calculated. And the gill net selectivity curves were plotted with variables fraction retained versus total length. According to the findings of this study gill nets with smaller mesh sizes cannot be used to catch small specimens of P. disjunctivus. But other endemic and indigenous fish species such as Puntius filamentosus (Dawkinsia singhala), Puntius chola, Puntius dorsalis and Rasbora daniconius have become vulnerable to smaller mesh sizes. These cyprinid fish species occupy littoral areas of reservoirs but these areas are now invaded by P. disjunctivus in the two reservoirs. Study concludes P. disjunctivuscannot be caught differently with other co-existing species with gill nets.

Keywords: P. disjunctivus, Coexisting fish species, Gill net selectivity

Journal Title : Journal of Technology and Value Addition

Volume : 2 Issue : 2

Page : 85 – 96

Submitted : May9, 2020; Accepted: August 7, 2020

Correspondence : wasana.wish@gmail.com

Changes in rainfall pattern and distribution are very important as it is mainly connected with the all agronomic practices in agriculture sector. Standardized Precipitation Index (SPI) is one of versatile tools for understanding the variations in monthly rainfall under different scenarios. Rainfall data were recorded in four Meteorological Stations which represent different regions in Uva Province namely Badulla, Monaragala, Okkampitiya and Wellawaya. The 12-month SPI from January to December which gives an idea about annual rainfall anomalies and, 6-month SPI from October to March and April to September and 3-month SPI from December to February were used for the analysis. Changes in SPI time series were analyzed using Change Point Analyzer software and Mann-Kendall test was used to identify the trends in SPI time series. There is a significant increasing trend in the annual rainfall anomalies in Wellawaya. However, there is low risk of having drought years in Badulla, Monaragala, Okkampitiya and Wellawaya after 2004. There is a significant increasing trend in North East monsoon period in Wellawaya and it implies high chance of getting extreme wet occurrences compared to previous years. However, there is no enough evidence of changes in the rainfall pattern of 6-month from April to September and 3-month from December to February. Finally, it can be concluded that there is a change in the pattern of rainfall anomalies in some locations of Uva Province.

Keywords: Change point analysis, Drought risk, Rainfall anomalies, Standardized Precipitation Index (SPI), Uva province

Journal Title : Journal of Technology and Value Addition

Volume : 2 Issue : 2

Page : 97 – 109

Submitted : November 23, 2020; Accepted: January8, 2020

Correspondence : kalaninelka93@gmail.com

Colour of the food is one of the most important quality attributes that affects the consumer’s acceptance since it gives the first impression of food quality. Due to proven safety and physiological advantage of the natural colourants over synthetic ones, interests are being increased into search of new natural colourants and the verification of the safety of existing ones. Roselle (Hibiscus sabdariffa L.) calyces have been known as a source that has characteristic intense red colouration due to presence of anthocyanins, which could be utilized as a natural colouring agent. This study was aimed to use of Roselle extract as a natural colourant in ice cream as a substitute to synthetic colourants. The physico-chemical properties were assessed using standard methods. The sensory evaluation was carried out to assess the colour, taste, texture, aroma and overall acceptability using a seven-point hedonic scale. The nutritional analysis of freshly made ice cream revealed that an increasing trend in titratable acidity from 0.24 to 0.37% (as citric acid), total soluble solid from 37.12 to 37.56 ºBrix, melting rate from 1.1 to 2%, ascorbic content from 2.75 to 3.45 mg/100 g, ash content from 0.73 to 0.79%, Colour parameter a­* value from 23.56 to 36.53 when the Roselle colour extract was increased from 0.10 to 0.25%. The results of this study revealed that the ice cream with 0.1% concentration Roselle colour is the best combination for maintain the physico-chemical and sensory qualities without any significant changes compared with the synthetic colourants. 

Keywords: Colour, Encapsulation, Extraction, Ice cream, Physico-chemical quality, Roselle