Indigenous knowledge, optimum recipe and storage stability of khurma, a cereal based traditional Nepalese product.

Khurma is a cereal based food indigenous to hilly regions of Nepal. It is a deep fried our confection prepared by mixing wheat our, rice our, semolina, ghee, sugar, spices mixture, milk and water. Despite its popularity, the scientic documentation and researches in khurma is scarce. Moreover, quality of khurma is often subject to variation due to differences in recipe and the data on storage stability is unavailable. Therefore, in this study recipe of the product was optimized using sensory analysis and the optimized product was analysed for physicochemical parameters and storage stability. Proximate analysis showed that optimized khurma had 2.48 ± 0.12%, 36.87 ± 0.34%, 9.51 ± 0.47%, 0.48 ± 0.03%, 0.06 ± 0.01% and 50.60 ± 0.82% of moisture, fat, protein, total ash, crude ber and carbohydrates respectively. Moreover, product was more stable in laminated packaging material compared to polyethene (PE) package. The results showed that khurma can be served and promoted as an energy dense snack.


Introduction
Traditional foods produced throughout the world by different communities. They are important components in the dietary pattern even in the developed societies [1] and are considered as an expression of history, culture and lifestyle [2].
Nepal is rich in ethnical and cultural diversity. Several varieties of traditional foods are available in the country. The knowledge of preparation is inherited from the ancestors and transferred from one generation to other through teaching and preparing at home. Quality of such products are maintained using sense for example by looking, smelling, touching, tasting and improved over generation through slight modi cations in the procedures [3,4].
Khurma is a deep fried our confection consumed mainly in hilly region of western Nepal (Fig. 1). It is reddish brown in colour and has closed palm or st like shape. The major ingredients for its preparation include wheat our, rice our, semolina, spices, ghee, sugar, milk and water. It is often prepared in major festivals and taken as a gift for the bridegroom's home in marriage ceremonies. Khurma preparation is common mainly in the ethnic communities like Brahmin, Chhetri and Newar. These communities are considered rich in tradition and cultures, and most of them are involved in agriculture and trade.
For traditional food to sustain in this modern era, it needs to meet the criteria of quality, nutrition, convenience etc. Further, appropriate packaging which could extend shelf life of these products is much important for proper distribution [5]. These are necessary for promotion and sustainability of traditional foods. However, recipe, technology, cultural aspects, composition, storage stability etc. of khurma has not been documented and quality of khurma is often subjected to variation depending on availability of raw material, processing steps, locality and convenience. Thus, this work aims to report indigenous knowledge, optimize the recipe and report storage stability of khurma. All raw materials required for the preparation of Khurma (re ned wheat our, rice our, sun ower oil, ghee, semolina, sugar and spices) were procured from the local market.

Cooking utensils
A rectangular wooden dye having length 30 cm and breadth 13 cm was chosen to shape the khurma. The wooden roller was used to atten the lump of dough. For frying stainless steel frying pan (locally called karai) was used.

Chemicals
Unless speci ed elsewhere, chemicals used in this study were purchased from Qualigen Fine Chemicals, India.

Survey
A survey, based on semi structured questionnaires was carried out to understand the indigenous knowledge of khurma such as cultural importance, formulation, preparation method, process variables and storage stability. A total of 25 people agreed and participated in the survey. They belonged to the ethnic group involved in khurma preparation from ancient times and were from the hilly communities of western Nepal (Fig. 1).

Preparation of khurma
Ghee was whipped properly and sugar was added to it. Whipping was continued until optimum consistency was achieved and our mixture (wheat our and either rice our or mixture of rice our and semolina) and powdered spices (equal proportion of clove and small cardamom) were added in it. It was mixed for about 4-5 min and kneaded to prepare dough by adding water or milk or their mixture. Then small portion of the dough (10 g) was taken and moulded in a rectangular shaped wooden dye and fried in re ned sun ower oil. The oil with acid value (AV) less than 0.20 and peroxide value (PV) less than 4.0 m. eq. peroxide oxygen/kg was accepted and used for frying purpose. After frying product was allowed to cool to room temperature and stored appropriately (Fig. 2).

Recipe optimization
The ratio of rice our and semolina, amount of sugar and ghee and the ratio of water and milk was varied depending on respondent but amount or proportion of other ingredients were fairly constant. So, in this study, these ingredients were optimized sequentially.

Ratio of rice our to semolina
To optimize ratio of rice our and semolina, six different types of khurma samples were prepared by varying their ratio as 100:0, 80:20, 60:40, 40:60, 20:80 and 100:0 keeping level of other ingredients constant. The ratio with highest sensory acceptability was taken as optimum.

Amount of ghee
Different types of khurma samples were prepared by varying the amount of ghee as 6, 9, 12 and 15% in the overall mixture and keeping proportion of other ingredient constant. Optimum level was estimated by selecting the level of ghee which resulted in khurma with highest sensory acceptability.

Amount of sugar
Four types of khurma samples differing in amount of sugar (6,9,12 and 15%) but with constant proportion of other ingredients were prepared and subjected to sensory analysis. The amount of sugar used which resulted in highest sensory acceptability was taken as optimum.

Ratio of water and milk
Six types of different khurma samples were prepared by varying the ratio of water to milk as 100:0, 80:20, 60:40, 40:60, 20:80 and 100:0 and keeping proportions of other ingredients constant. The ratio which resulted in highest sensory acceptability was taken as optimum.

Study of storage stability
For evaluation of storage stability, khurma prepared with optimized recipe were stored in three different conditions viz., open condition (without packaging), packed in polyethene (PE) pouch (35 µm) and laminated pouch (PE 12µm + MET BOPP 20µm). These products were stored for 50 days and analysed for acid value (AV) and peroxide value (PV) at the interval of 10 days viz., 0, 10, 20, 30, 40 and 50 days. According to regulatory standard of Government of Nepal the maximum permissible limit for acid value and peroxide value of extracted fat for deep fried product such as noodles is 1 mg KOH/g and 10 m. eq. peroxide oxygen/kg [6] . These criteria were taken for judging the loss of storage life of khurma.

Proximate analysis
Moisture (hot air oven method), fat (solvent extract in soxhlet), protein (kjeldahl method), crude ber, total ash and acid insoluble ash were determined by the method described previously [7]. Carbohydrate content was determined by subtracting moisture, fat, protein, crude ber and ash contents from 100.

Determination of acid value (AV) of extracted fat
Khurma sample was powdered and its fat was extracted with petroleum ether. After evaporation of solvent, AV was determined by the method described previously [8].
2.2.7. Determination of peroxide value (PV) of extracted fat Khurma sample was powdered and its fat was extracted with hexane. After evaporation of solvent, PV was determined by the method described previously [8].

Energy value
The energy value of the sample was determined by multiplying the physiological energy value for carbohydrate (4 kcal/g), protein (4 kcal/g) and fat (9 kcal/g) [9].

Sensory analysis
Sensory analysis was carried out using 9-point hedonic rating test [10]. Ten semi-trained panelists consisting of food technologist who consumed khurma frequently in different occasions were selected and asked to rate the sample for overall sensory acceptability.

Data analysis
All analytical measurements were made in triplicates. Sensory data were analysed using non-parametric

Indigenous knowledge of khurma
Twenty-ve different individuals involved in regular khurma preparation were involved in the survey. Among them 96% were female and rest (4%) were male. Age of respondents was between 25-50 years.
Among racial groups the highest numbers of respondents were brahmin followed by newars and chhetri.

Ethnic community involved and cultural importance
Khurma preparation and consumption was found to be popular among Bhramhin, chhetri and newar communities belonging to the western hilly region of Nepal. It is also called mudkyaula by some peoples due to its closed palm or st (muththi, in nepali) shape. It is prepared and served mostly in festivals like Tihar (Depawali), Makar Sankranti and other ritual occasions. Khurma is also taken to bridegroom's home as a gift (koseli/sagun) from their in-laws during marriages.

Ingredients and methods of preparation
The ingredients for the preparation of khurma are wheat our, rice our, semolina, sugar, cow ghee, spices powder (clove and small cardamom), milk, water and re ned sun ower oil. The variety of wheat and rice is not speci c. However, there were some variations in the use of these ingredients depending on the respondents.
For preparation of khurma, ghee is whipped and equal amount of sugar is added to it. Then whipping is continued until required doneness and our mixture (50 % wheat our and 50 % either rice our or mixture of rice our and semolina) is added to it. Mixing is continued for another 4 -5 min and the mixture is kneaded into dough by adding either water, milk or their mixture. From the dough prepared in this way, about 10 g is taken and moulded in a attened wooden dye with wooden roller (Fig. 3) into appropriate shape and then deep fried in re ned sun ower oil with mild heating until reddish brown colour appears which takes about 7 min to complete. Finally, the product is cooled to room temperature and packed.

Storage stability of khurma
Most of the respondents packed it in air-tight glass or plastic containers. From preliminary survey it was found that 25% people believed that it has shelf life less than 1 month, 45% people believed that it has shelf life about one month and remaining 30% people claimed that it has shelf life more than one month packaging in air tight container. Main defects on storage was hardening of texture and brittleness.

Recipe optimization
Variation in the ratio of rice our and semolina, ratio of water and milk, amount of ghee and amount of sugar signi cantly affected overall sensory acceptability of khurma (p<0.05) (Fig. 4). The rice our to semolina ratio of 40:10 had signi cantly high sensory acceptability compared to other proportions. Addition of milk did not affect sensory acceptability until water to milk ratio of 60:40 but increased signi cantly at water to milk ratio of 40:60 and remained unchanged on further increasing the proportion of milk. Moreover, increase in sugar content to 12% signi cantly increased sensory acceptability but decreased on further increasing the amount. On the other hand, increasing the amount of ghee beyond 6% decreased overall sensory acceptability. The optimized recipe of khurma from sensory analysis is given in Table 1.

Proximate composition of khurma
Khurma prepared from optimized recipe was high in carbohydrates and fat contents, moderate in protein and minerals, and low in ber content ( Table 2). The low moisture content confers crisp texture and as the high moisture favours microbial growth the product may be relatively stable against microbial spoilage [11][12][13]. The fat in khurma is mainly contributed by ghee and sun ower oil. Ghee (also known as clari ed butter) has been utilized as a therapeutic agent in Ayurvedic system of medicine. Though some studies suggested unhealthy effects of ghee consumption due to its saturated fatty acid contents, several other studies have reported its bene cial effects, including decrease in serum total cholesterol, low density lipoproteins and triglycerides; decreased liver total cholesterol, triglycerides, and cholesterol esters [14,15]. Also, lower prevalence of coronary heart diseases has been reported in men who consumed higher amount of ghee [14]. Further, sun ower oil is rich in health promoting oleic and stearic acids [16]. Protein, ash and ber are contributed by wheat our, semolina and rice.
Moisture, carbohydrates, crude ber content is lower whereas fat, protein, ash content of khurma is higher compared to those reported for selroti (a cereal based traditional product) [17]. The product has moisture content comparable to some sweet plain biscuits varieties, ash content comparable to some sweet lled biscuits varieties, and protein content comparable to some varieties of snack biscuits, sweet biscuits and crackers whereas it has higher fat content compared to these industrialized biscuits [18]. Moreover, comparable fat content and energy values have been reported in wheat based biscuits improved beniseed and unripe plantain [19]. This implies that, proximate composition of khurma is comparable to industrialized product thus it has commercial potential.

Acid value of extracted fat
Types of packaging and time of storage signi cantly affected acid value (AV) of extracted fat (p<0.05). Laminated pack (12 µm PE and 20 µm Met BOPP) was more effective for stability of product in terms of acid value compared to PE (35 µm) pouch. The AV of extracted fat increased from 0.51 mg KOH/g at the beginning of storage to 1.73, 0.97 and 0.90 mg KOH/g at 50 days of storage in products kept without packaging, in PE pouch and in laminated pouch respectively (Fig. 5). If the maximum permissible limit of AV of extracted fat for deep fat fried product such as noodles i.e. 1 mg KOH/g is considered for khurma [6], it can be stored for slightly more than 30 days without packaging and can be stored safely up to 50 days in PE and laminated pouches.

Peroxide value of extracted fat
Type of packaging and storage days signi cantly affected peroxide value (PV) of extracted fat of khurma (p<0.05). In terms of PV, the products kept in laminated pouch (12 µm PE and 20 µm Met BOPP) had more stability compared to those packed in PE (35 µm) and kept without packaging. The value of PV of extracted fat increased from 3.96 m. eq. peroxide oxygen/kg at the beginning to 25.49, 20.56 and 17.05 m. eq. peroxide oxygen/kg at 50 days of storage in product kept without packaging, in PE pouch and in laminated pouch respectively (Fig. 6). If the maximum permissible limit of PV of extracted fat in deep fat fried product such as noodles i.e. 10 m. eq. peroxide oxygen/kg is considered for khurma [6], it can be kept for less than 10 days without packaging, slightly more than 10 days in PE pouches and slightly more than 20 days in laminated pouches. However, the product had not developed rancid avor when it reached the peroxide value of 10 m. eq. peroxide oxygen/kg. Thus, further researches are needed to determine maximum acid value and peroxide value for storage stabilities.
Increase in free fatty acids and peroxides causes product to become rancid and unacceptable. Light, oxygen, pro-oxidants, hydrolytic enzymes increases the rate of lipid degradation [20][21][22]. This might be the reason behind lower shelf life of khurma kept without packaging. Moreover, laminated packaging have more barrier properties viz., low gas transmission rate (GTR) and water vapour transmission rate (WVTR), so laminated packaging materials are expected to provide longer shelf life [23]. Increase in free fatty acids and peroxide values in food products with storage days have been reported [24][25][26][27].

Conclusion
In summary, khurma prepared with optimized recipe was high in carbohydrates, fat, and energy, moderate in protein and minerals, and low in ber contents. The product is more stable in laminated package with more than 20 days of storage life when compared to regulatory standards of deep fat fried product (noodles) for acid values (AV) and peroxide values (PV). However, further researches are required to determine quality standards for khurma and its shelf life at different conditions of packaging.   Changes in acid value (AV) with type of packaging and storage period