Naturally Fermented Ethnic Soybean Foods of India
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Accepted Manuscript Naturally Fermented Ethnic Soybean Foods of India Jyoti Prakash Tamang PII: S2352-6181(15)00004-9 DOI: 10.1016/j.jef.2015.02.003 Reference: JEF 11 To appear in: Journal of Ethnic Foods Received Date: 15 January 2015 Revised Date: 22 January 2015 Accepted Date: 6 February 2015 Please cite this article as: Tamang JP, Naturally Fermented Ethnic Soybean Foods of India, Journal of Ethnic Foods (2015), doi: 10.1016/j.jef.2015.02.003. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT 1 Naturally Fermented Ethnic Soybean Foods of India 2 3 Jyoti Prakash Tamang 4 5 Department of Microbiology, School of Life Sciences, Sikkim University, 6 th Mile, 6 Tadong 737102, Sikkim, India 7 8 9 10 11 12 Corresponding author: Professor Dr. Jyoti Prakash Tamang*, Department of Microbiology, 13 Sikkim University, 6 th Mile, Tadong 737102, Sikkim, India (e-mail: 14 [email protected]; Mobile: +91-8016099902;MANUSCRIPT Tel: +91-3592-251188) 15 16 Running title: Indian fermented soybeans 17 Keywords : Ethnic foods, naturally fermented soybeans, kinema, Bacillus 18 ACCEPTED 1 ACCEPTED MANUSCRIPT 19 Abstract 20 Kinema , hawaijar , tungrymbai , bekang, aakhone and peruyaan are naturally fermented ethnic 21 soybean foods of India popular among the Mongolian-origin races in the Eastern Himalayas. 22 Bacillus subtilis is the dominant functional bacterium in all naturally fermented soybean foods 23 of these regions. Though there is a good demand of ethnic fermented soybeans foods among 24 the local consumers in North East India, the production is limited to household level. Ready- 25 to-use pulverised starter culture for kinema production can be introduced to kinema -makers or 26 similar sticky fermented soybean foods of North East India adapted to local conditions for 27 more income generation. Ethnic fermented soybeans are one of the major food resources in 28 the Eastern Himalayas to supplement inexpensive, high digested plant protein with low 29 fat/cholesterol content and high nutritive value with antioxidant and other health-promoting 30 properties in the local diet as functional food. 31 MANUSCRIPT ACCEPTED 2 ACCEPTED MANUSCRIPT 32 Introduction 33 In the Eastern Himalayas, soybean [Glycine max (L.) Merrill, family Leguminosae, sub- 34 family Papilionaceae] is grown under rain-fed conditions in upland terraces as a sole crop as 35 well as a mixed crop with rice and maize up to an elevation of 1500 m (Fig 1). Soybean, 36 locally known as bhatmas in Nepali language, is traditionally used to prepare various 37 fermented and non-fermented recipes in the Eastern Himalayan regions of Nepal, India and 38 Bhutan [1]. Soybean was probably introduced to India from China through the Himalayas 39 several centuries ago and some believe that soybeans were also brought via Myanmar by 40 traders from Indonesia [2]. Two indigenous varieties of soybeans ‘yellow cultivar’ and ‘dark 41 brown cultivar’ (Fig 1) are grown in between May and June and harvested in November. 42 Locally grown soybeans are harvested and dry seeds of soybeans are naturally fermented into 43 flavoursome and sticky product in eastern parts of Nepal, Darjeeling hills, Sikkim, North 44 Eastern regions of India, and southern parts of Bhutan by the Mongolian races. Some of the 45 common ethnic non-salted sticky fermented soybeanMANUSCRIPT foods of Eastern Himalayas are kinema 46 (Nepal, Darjeeling hills, Sikkim and south Bhutan), hawaijar (Manipur), tungrymbai 47 (Meghalaya), bekang (Mizoram), aakhone (Nagaland), peruyaan (Arunachal Pradesh) (Table 48 1). This article will examine kinema’s characteristics, microbiology of kinema and health 49 benefits of kinema including hawaijar, tungrymbai, bekang, aakone, peruyaan. 50 51 Kinema 52 Kinema is an ethnic fermented soybean food of Nepali community in the Eastern Himalayas 53 which is sticky,ACCEPTED slightly alkaline product with a slight ammoniacal flavour produced by 54 natural fermentation. It is a whole-soybean fermented food with sticky texture, gray tan 55 coloured and flavoursome [3]. During traditional production of kinema , the small-sized (~ 6 56 mm) ‘yellow cultivar’ soybean dry seeds are selected, washed, soaked overnight (8-10 h) in 57 water. Soaked soybeans seeds are taken out and put into the container with fresh water, and 3 ACCEPTED MANUSCRIPT 58 boiled for 2-3 h until they are soft. Excess water is drained off and the cooked soybean seeds 59 are filled into the wooden mortar locally called ‘okhli, and are cracked lightly by a wooden 60 pestle locally called ‘muslo’ to split the cotyledons. This practice of cracking cooked seeds of 61 soybeans is observed only during kinema production unlike other similar fermented soybean 62 foods of Asia and North East India probably to increase the surface areas for speed 63 fermentation by aerobic spore-forming Bacillus spp. About 1 % of firewood ash is added 64 directly to the cooked soybeans and mixed thoroughly to maintain the alkaline condition of 65 the product. Soybean grits are placed in a bamboo basket lined with locally grown fresh fern 66 called (Glaphylopteriolopsis erubescens ). The basket is covered in a jute bag and left to 67 ferment naturally at ambient temperatures (25-40 o C) for 1-3 days above an earthen oven 68 kitchen (Fig 2). During summer, the fermentation time may require 1-2 days while in winter it 69 may require 2-3 days. In eastern Nepal, local consumers prepare dark brown local varieties of 70 soybean seeds rather than yellow-coloured seeds for making kinema [4]. Similarly, they 71 commonly use Ficus (fig plant) and banana leavesMANUSCRIPT as wrapping materials instead of fern 72 fronds. Other methods remain the same. Completion of fermentation is indicated by the 73 appearance of a white viscous mass on the soybean seeds and the typical kinema flavour with 74 a slight odour of ammonia. 75 Shelf-life of freshly prepared kinema (Fig 3) remains for 2-3 days in summer and 76 maximum a week in winter without refrigeration. It may be prolonged by drying in the sun for 77 2-3 days. Dried kinema is stored for several months at room temperature. Preparation of 78 kinema varies from place to place and is still restricted at the household level. It is interesting 79 to note the mountainACCEPTED women using their indigenous knowledge of food production prepare 80 kinema . This unique knowledge of kinema -making has been protected as a hereditary right 81 and passed from mother to daughter, mostly among the Limboo. 82 Kinema is eaten as curry with steamed rice. Delicacy of kinema can be perceived by its 83 appealing flavour and sticky texture. Fresh kinema is fried in vegetable oil, with chopped 4 ACCEPTED MANUSCRIPT 84 onions, tomatoes and turmeric powder. Salt and sliced green chillies are added and fried for 3- 85 5 min. A little water is added to make thick gravy, and cooked for 5-7 min then the kinema 86 curry (Fig 3) is ready for serving with steamed rice. Dried kinema is sometimes mixed with 87 leafy vegetables to make a mixed curry. Consumers like kinema mostly due to its typical 88 flavour and sticky texture, and some people dislike the product due to its strong umami -type 89 flavour [5] and mucilaginous texture. 90 Kinema production is a source of marginal income-generation for many families in the 91 Eastern Himalayas. Kinema is sold in all local periodical markets locally called ‘haats’ in 92 eastern Nepal, Darjeeling hills, Sikkim and southern parts of Bhutan by rural women. 93 Usually, it is sold by volume taking in a small silver mug containing 150-200 g of kinema , 94 and pack in the leaves of fig plant ( Ficus hookeriana ) locally called ‘nevara’, and then tied 95 loosely by straw. Poly-bags are not used to pack kinema. One kg of kinema costs about Rs. 96 100. Average 5 kg of kinema is sold by each seller in a local market and about 60 % expenses 97 are incurred on purchase of raw soybeans, fuel MANUSCRIPTfor cooking, transportation from village to 98 market, etc., and 40 % of profit is made [1]. This profit is spent on children’s education, 99 procuring essential commodities not locally available, and other domestic expenses. Though 100 there is good demand of kinema in the local markets, production of kinema is still confined to 101 home production, there is no organised processing unit or factory of kinema production. 102 Kinema making technology has not been recognised as small-scale industry for getting 103 financial support or loan by any public sector bank or financial institution, or, neither has it 104 been incorporated in the rural development programmes of the government in Nepal, India 105 and Bhutan. ACCEPTED 106 107 Microbiology of kinem a 108 Several species of Bacillus have been isolated from kinema which include Bacillus subtilis, B. 109 licheniformis, B. cereus, B. circulans, B. thuringiensis and B. sphaericus at an average load of 5 ACCEPTED MANUSCRIPT 110 10 8 cfu/g [6,7,8]. However, B. subtilis is the dominant functional bacterium in kinema [9,10]. 111 Besides Bacillu s, Enterococcus faecium (10 7 cfu/g) ; yeasts- Candida parapsilosis and 112 Geotrichum candidum (10 4 cfu/g) have also been reported from kinema [6,8]. 113 It is observed that rich microbial diversity in various sources particularly soybean, 114 equipment and leaves as wrapping materials harness microbiota for natural fermentation of 115 kinema [8].