Physico-chemical and sensorial attributes of Sikkim mandarin (Citrus reticulata).

In the north-east region 11.7% area is occupied (57.2 thousand ha) by citrus cultivation and it contributes 6.6% (3.6 thousand tonnes) in total citrus production (NHB 2006). A few ecotypes of mandarin (Citrus reticulata Blanco) including Sikkim mandarin, Darjeeling mandarin and Khasi mandarin are excellent in quality and have good export potential (Singh 2006). Among north-eastern states, Sikkim contributes only 2% in citrus production by covering 5% area (NHB 2006). The major citrus growing belts of Sikkim are southern part of north district, central part of south Sikkim, central part of east Sikkim and southern part of west Sikkim. Mandarin is mainly grown in the lower hills of Sikkim under the sub-tropical humid climatic conditions with the altitudinal variations of 3 000′–4 200′. Citrus growing belts come under the heavy rainfall zone. The average rainfall in 4 different belts was 300 cm (north district), 240 cm (south district), 330 cm (east district) and 200 cm (west district). The west and south districts receive relatively less rainfall than east and north districts. The average temperature in these belts is 16–18°C with maximum of 28.5°C and minimum of 5°C and the average humidity is generally 74% with the maximum of 90% and minimum of 50%. The physico-chemical and sensorial attributes of mandarin cultivated in different areas of Sikkim have not been studied so far. Since these attributes of fruits not only determine the quality of processed products but also quality of planting material. The present investigation aimed to study a variation in the physico-chemical and sensorial attributes of fruits of mandarin in Sikkim. Fruits were collected from 4 different citrus growing belts of Sikkim during December and analysis was carried out at ICAR Sikkim Centre, Tadong, Gangtok, during 2007–09. Since from each district 2 important citrus growing areas were identified and from each area 4 representative orchards were selected. From each representative orchard 300 fruits were collected from 15 randomly selected healthy plants. The average mean values of physico-chemical and sensorial attributes of 4 orchards were considered as the fruit characters of that area and the average of mean value of attributes of both the areas was considered as the character of mandarin of each district. The areas selected in different districts of Sikkim are: Pasingdang and Loom (north), Sadam and Rabong (south), Central Pandam and Pachak (east) and Dikling and Soreng (west). The 4 districts were considered as 4 treatments; T1, north district; T2, south district; T3, east district, and T4, west district. The fruits collected from each orchard graded into 4 categories (I, II, III and IV) on the basis of their weight, and physico-chemical and sensory attributes were studied by taking 25 fruits from each category. The average value of attributes under four categories was considered as the representative attributes of that orchard. The fruit weight under different categories of fruits was measured by considering mean weight of all the fruits. The juice percentage was calculated by dividing juice content with fruit weight and by multiplying the resultant with 100. The fruit firmness was measured by standard penetrometer (scale 0–10 kg/cm2). The total soluble solid (TSS) was recorded with ERMA hand refractometer (0–32° Brix). The titrable acidity, vitamin C, reducing sugar and total sugar were determined by following methods of Ranganna (1991). The TSS/acid ratio was calculated by dividing TSS and titrable acidity and similarly sugar/acid ratio was calculated by dividing sugar and acid. A panel of 6 judges familiar with citrus fruit juice was trained prior to the start of the experiment by use of the triangular test method (ISO 4120, 1983). Flavour profiling (ISO 6564, 4985, 1985) was used to evaluate juices. Flavour descriptive attributes of citrus fruit juice unanimously agreed upon were flavour intensity, sourness, sweetness and overall impression of the juice. Judges were served with coded juice samples at the ambient temperature. The attributes were rated *Short note 1Scientist, Horticulture (email: kkhort2003 @yahoo.com), 2Scientist, Horticulture (email: ashokhort @gmail.com), 3Joint Director, (email: hr19@rediffmail.com), 4Research Associate, Mini Mission-I (email: sosimplemp @yahoo.com), 5Research Associate Mini Mission-I (email: mr.brijeshpandey@gmail.com)