DSP/National Dairy Development Board, GPO Box 7445, Kathmandu, Nepal
Nepal was the first country to produce cheese from yak/Chauri milk in the high alpine region of the country. This product is popularly known as yak cheese. Nepal produced around 350 t of cheese during 1998/99, out of which around 150 t was from yak and Chauri milk. This activity is focused in the districts of Mount Everest trekking route and the Rasuwa district, adjoining to the capital city. Many more districts, stretching over the northern alpine region, raise yak as the main means of subsistence. Yak milk is traditionally processed into fermented milk, and then churned out to produce local yak butter and buttermilk. Buttermilk is further processed into sher, a cottage cheese type product. If fermented, produces sewsew, and if pressed and dried or dried without pressing it becomes Chhurpi, a dried hard casein product. Chhurpi is widely consumed by Himalayan people as a source of nutrients, and is chewed to maintain salivation during mountain climbing. Traditional and indigenous technologies are in place to produce milk products that have long shelf life in the yak rearing countries of China, Bhutan, India, Mongolia, Pakistan, Nepal and so on. There is a need to upgrade the existing indigenous technology to produce safe and hygienic yak milk products at commercial scale. Human resource development and training facilities, yak milk processing industry association and marketing and promotion are the major issues to be addressed to promote the yak trade. The International Yak Congress should come with a consensus to establish an International Yak Research Centre that could carry out the research, education and training, development of appropriate technology, standardisation of products and processes, and other areas identified by the yak-producing countries. Diversification is very essential to generate sustainable income, and it is only possible when proper practical training and technology is transferred to the beneficiaries.
Keywords: Cheese, Chhurpi, indigenous technology, promotion, yak cheese
Diversification should entail producing varieties of milk products from yak/Chauri milk, and that also adds value to the species. This is basically intended to fetch more return for the producers per unit of milk produced. Yak and Chauri have been reared and herded on either side of Himalayan range, from Tibet in the north to the southern slopes covering parts of India, Nepal, and Bhutan (Joshi et al. 1994). Yak butter is considered as an excellent source of energy, and local people say this is very good for the body and strength. A long tradition of milk production, processing and consumption exists in the high alpine Indo-China region. The essence of processing was concentration and increasing the storage life of milk by reducing the water content through concentration of protein or fat, or fat and protein together. The water content is traditionally removed through evaporation or coagulation and draining or other processes like separation of valuable constituents of milk that can be stored for a considerable length of time, and which fetch better prices. This resulted in the production of butter, ghee, Chhurpi and so on. Butter and ghee are concentrated milk, with much longer shelf life than milk. Similarly, Chhurpi is a milk protein concentrate with very low moisture content. In the western world, milk protein was not concentrated into Chhurpi, but into cheese. There was added advantage in cheese making: Protein and most of milk fat could be concentrated, stored and transported. The Swiss developed appropriate technology to produce cheese in the Alps Mountain. Later on, this technology was transferred to Nepal through FAO technical assistance in 1952. Thus, first yak cheese plant was established in Langtang valley. This dates back to first historic yak cheese production in Nepal, and Nepal became the first country in Asia to start a cheese industry. It was the only country in the world producing yak cheese before 1980s. Hard Swiss Gruyere type cheese was produced. This cheese is popularly known and marketed by the name of Yak Cheese today (Thapa 1996).
Nepal produced around 350 t of cheeses during 1998/99, out of which about 150 tonnes was from yak and Chauri milk (Table 1).
Table 1. Yak cheese production in Nepal (1998/99).
Total production by private sector processors
Yak cheese production by the six Dairy Development Corporation (DDC) plants
Approximate total yak cheese production
Chhurpi is the dried hard casein product traditionally produced from yak or chauri (crossbred yak × chauri cattle) milk in the Himalayan region of Nepal, Sikkim and Bhutan. Similarly, Serkam is a local dairy product, prepared by boiling and draining liquid portion of buttermilk and in some cases whey. The remaining solid is Serkam. It is used fresh or can be used after certain period, ranging between days to months. However, long storage causes natural fermentation, giving off typical flavour but is liked very much by Jirel and Sherpas. In China, excellent examples of diversification exist, including the processing of yak milk into powder.
The commercial Chhurpi makers prepare the product in a batch using 169 litres of skimmed milk (SM) under local condition. The workflow of standardised process adopted by local Chhurpi maker in Nepal is described below.
Two hundred litres of milk (6.5% fat and 9% solid-not-fat) is separated to 31 litres of 40% fat cream and 169 litres, skimmed milk (SM). SM is heated to 60–65°C in aluminium kettle under direct fire. Then 40 litres of Dahi (fermented milk) made by using SM is added, with constant stirring. The curdled mass is cooked by boiling for 30 minutes or until long threads or chains are formed. Then 50–60 litres of whey is drawn out. The kettle is taken out of fire after colour changes to creamy yellowish. The cooked curd is strained and pressed for 24 hours using stone weights. The pressed curd is cut into small cubes and air-dried on a bamboo mat in a well-ventilated room. The product is hard enough after 12–15 days of air-drying. Alternatively, the product is smoke-dried after 10 days of air-drying. Chhurpi yield is 4.5% with 8–10% moisture, 8–9% fat and 80% protein on dry matter basis. The technology has been very useful to the remote and mountainous milk producers who do not have access to raw milk market. The producers are able to convert perishable milk into long life products like Chhurpi, butter and ghee. The technology has been quite useful to generate cash income and local employment at the rural level.
Further work is needed to improve the quality and the profitability of final product and to improve the technology appropriate to the rural producers.
Figure 1. Chhurpi sale in Kathmandu market.
Thapa and Sherpa (1994) reported the yak cheese manufacturing technology adopted by Dairy Development Corporation, Nepal. Thapa (1997) described further improved yak cheese making procedures used by the Nepalese yak cheese manufacturers. The recently improved and standardised method is presented below.
Raw milk (7–8% fat and 9.5–10% solids not-fat ) is used. Standardise the milk to 3.5% fat by cream separation; cream is churned into butter. Follow in-can pasteurisation of cheese milk at 65°C/5 minutes by immersing in a boiling water bath, and cooling in water-trough to 33–35°C. Transfer the cheese milk to 200–300 litres copper kettle and put on a traditional fireplace. Add 0.5% culture (Str. thermophilus and Lactobacillus helveticus 1:1). After 5 minutes add rennet solution (2.5 g dissolved in 500 mL boiled and cooled water for 100 litres milk) and stir for one minute before allowing to set (33°C) by covering the kettle. Turn the top curd using scoop after 30 min and allowed to set for 5 more minutes. The curd is cut, and after 5 min stirring started very slowly. Continue stirring for 25 min (32°C) before cooking is started. This is called pre-stirring. The curd is cooked to 50–53°C in 30 minutes using firewood. The temperature is gradually raised in the following manner: 32–35°C/first 10 min; 35–45°C/second 10 min; 45–50°C/last 10 min. After the temperature reaches 50°C, continue stirring for 25–30 minutes until the curd is ready for moulding and pressing. Pressing: Cheese is pressed in two stages; Pre-pressing; the blocks are tuned after 5 min, 15 min, 45 min and after 1.5 hours. Wet cloth is replaced by dry cloth after 1.5 hours. Final pressing; fifth turn is given after 3.5 hour and dry cloth is used. After six hours, cheese is pressed without cloth till next morning. Total pressing time ranges between 16–17 hours. Cheese blocks are saturated (24%) generally for 48 hours, but the saturating time is proportional to the weight of the blocks. 5–6 kg blocks are saturated for 36 hours whereas 14–15 kg blocks are saturated for 72 hours. The cheese blocks are stored for ripening at 10-12°C and 85–90% humidity for first two weeks; and then at temperatures of 20–22°C and 75–80% humidity for 2–8 weeks. After this period cheese is transferred to maturing store at temperatures of 8–10°C till marketed. In high alpine region (2500–3400 metres above sea level), it is stored under ambient temperature condition. For first week, cheese is washed and turned every day, then twice a week for 3 weeks consecutively. The cheese develops good flavour after 5 months of ripening. Green cheese yield is 11% and 6–8% of original weight is lost after 5 months curing.
Excellent potential of diversifying processing and marketing of yak milk-based products exists in the whole of the yak-rearing zone of Indo-China. Yak cheese is an established name for the yak milk-based product. Nepal produces less than 200 tonnes, and Yak cheese is almost an established brand name. The benefit of this established name could be taken advantage of by the other yak rearing countries. Yak cheese has a well-established market, particularly in the tourist-dominated areas of Nepal, and is fetching relatively high prices. Yak cheese demand is not even fulfilled in Nepal, and there is demand from other countries too. Yak cheese has, therefore, a big potential. Yak cheese has market expansion potential in neighbouring countries too. However, low level of production and poor marketing channels has constrained the export of the product. Countries with sizeable yak milk production can develop the yak cheese production to a commercial scale, targeting export market in the west.
Basically, to promote diversification, there is a need, firstly, to upgrade and standardise the indigenous technology to commercialise the indigenous system. Secondly, already established technology like Yak Cheese Technology could be exploited to a higher level of production, targeting export market. Nepal could assist the other countries in this regard. Marketing and promotional campaign are very essential to expand the trade. Proper packaging, using registered brand name, can ensure higher profit for the producers and marketers. The development of a regional brand for yak cheese is an option.
The International Yak Congress is an appropriate forum, and should come out with a consensus to establish an International Yak Research Centre, that could carry out the research, education and training, appropriate technology development, products and process standardisation, and other identified priority areas. Diversification is very essential to generate sustainable income, and it is only possible when proper practical training and technology is transferred to the beneficiaries. The International Yak Congress should also consider establishing a Technical Exchange Programme to share the experiences existing within the region, through multi-lateral donor assistance.
The International Yak Congress should focus on the following areas to promote diversification for the increased income to the yak and Chauri farmers:
Joshi D.D, Lund P.N., Miller D.J. and Shrestha S.K. 1994. Yak production in Nepal. In: Rongchang Zh., Jianlin H. and Jianping W. (eds), Proceedings of the 1st international congress on Yak held in Lanzhou, P.R. China, 4–9 September 1994. Supplement of Journal of Gansu Agricultural University, Lanzhou, P.R. China. pp. 105–112.
Thapa T.B. 1996. Yak cheese production in Nepal: An overview. In: Miller D.G., Craig S.R. and Rana G.M. (eds), Proceedings of a workshop on conservation and management of yak genetic diversity held at ICIMOD, Kathmandu, Nepal, 29–31 October 1996. ICIMOD (International Centre for Integrated Mountain Development), Kathmandu, Nepal. pp. 165–171.
Thapa T.B. 1997. Prospects of processing and marketing of yak milk based products from Nepal. In: Rongzhen Y., Xingtai H. and Xiaolin L. (eds), Proceedings of the 2nd international congress on yak held in Xining, P.R. China, 1–6 September 1997. Qinghai People's Publishing House, Xining, P.R. China. pp. 12–16.
Thapa T.B. and Sherpa R. 1994. Manufacture of yak cheese in the alpine region of Nepal. Brief Communications, 24th International Dairy Congress. Melbourne, Australia. 37 pp.