The research study was conducted to evaluate the quality characteristics of mushroom-wheat-oats enriched flour which could be used as a protein supplemented food. In this study, wheat flour was replaced with mushroom flour at different levels that is 5% (F₁), 7% (F₂), and 10% (F3) and without mushroom flour was kept as control (F_o). Oats was added in both flours (15%). Flours were analyzed for chemical and sensory parameters. Protein content of the prepared flours were increased from 14.04% to 16.49% as compared to control along with a significant increase in ash (0.69–1.26%), sodium (773.51-1226.56 mg/100g), iron (6.97–15.85mg/100g), potassium (1213.02-3388.78 mg/00g), calcium (103.41-132.00 mg/100g), manganese (11.18-16.54 mg/100g). Results from chemical analyses and organoleptic evaluation indicate that good quality flour can be prepared by substituting wheat flour with 5% mushroom flour and addition of oatsflours. Also, the produced flour was compared with locally available wheat flours. The results showed that mushroom fortified flour contained higher ash, protein, fibre and Fe than locally available wheat flours. Protein Energy Malnutrition (PEM) of the Bangladeshi population can be reduced through the development of flours in this way.

Abbreviations: IFST: Institute of Food science and Technology; BCSIR: Bangladesh Council of Scientific and Industrial Research; BHA: Butylated hydroxyanisole; BHT: Butylated hydroxytoluene; SPSS: Statistical Package for the Social Sciences; PEM: Protein Energy malnutrition

Wheat flour is one of the most commonly used plant foods available. It is mainly used for production of roti, bread, biscuits and other bakery products. Use of wheat flour is also common in Bangladesh. We are consuming wheat flour in various ways in our day to day life from morning till night. Wheat flour is a good source of energy, carbohydrate, fibre and protein. It is also enriched with B-vitamins like B1, B2, B6, vitamin E and micronutrients like iron and zinc [1-2]. However these vitamins and nutrients remain concentrated in the outer layer of wheat grains. Eventually a significant portion is lost from wheat flour while milling and processing [3]. Thus fortification of wheat flour is a must for recovering these nutrients. It will also help in improving fibre and protein content. In developed countries it is a common phenomenon to fortify wheat flour with different nutrients, fibre and plant proteins for increasing the quality of wheat flours and also products developed from it.

Edible mushrooms are fungi that contain high quality protein (10-40%), carbohydrate (3-21%) and dietary fiber (3-35%) on dry weight basis depending on species [4]. Oyster mushroom (Pleurotus ostreatus) is a edible mushroom, cheapest and easiest to grow compared to all the cultivated edible mushrooms, is a great source of different types of nutrients such as protein, fibre carbohydrate. Mushroom proteins specially contain essential amino acids needed in human diet and are especially rich in lysine and leucine, which lacks in most cereal foods [5-6]. Apart from taste and flavour, the fruit body of oyster mushroom is considered as sources of minerals as well as antioxidants. Oyester mushroom contains antioxidant components such as ascorbic acid, β-carotene and α-tocopherol [7-10]. Several researches had proven that high amounts of antioxidants may prevent the oxidative stress caused by the presence of free radicals which lead to disorder in physiological effectiveness such as cell damage, generating of cancer cell and brain cell aging. Therefore, oyster mushroom is one of the second most cultivated mushrooms and cultivated all over world.

Oat is also a nutritious cereal popular around the world. Oat is characterized by a high content of lipids and a high protein content that can be a great exogenous source of amino acids [11-13]. Oat contains a smaller amount of carbohydrates, and a large content of dietary fibers (mainly glucans and pentosans) as compared to other cereals. Also, oat can be a good source of vitamins. Having a high content of soluble fibre (β-glucans), products made from oat have a positive effect on prevention of coronary heart disease, chronic disease conditions, such as diabetes, atherosclerosis and digestive diseases. Oat flour is also a good source of antioxidants which had effectiveness equal to that of commonly used commercial antioxidants such as BHA and BHT [14].

In this present study, Wheat flour is fortified with mushroom and oats flour and its nutrition, mineral contentwas determined.

The study was carried out in the laboratory of Quality Control Research Section of Institute of Food Science and Technology (IFST), Bangladesh Council of Scientific and Industrial Research (BCSIR), Bangladesh.

Raw materials
Oyster mushroom (Pleurotus ostreatus) was collected from the National Mushroom Development and Extension Center, Savar, Bangladesh. Oat flour and other ingredients were collected from the local market.

Preparation of raw materials
Mushrooms were dried in a hot air drier at 50°C for 6h and then ground into flour in a grinder. Finally the flour was sieved using 0.25 mm sieve.

Method of preparation of Mushroom flour
Wheat flour was replaced with mushroom flour in three different proportions 5, 7, and 10% and designed as F₁, F₂, and F₃, respectively, whereas F₀ (without mushroom flour) was kept as control. The percentage of oat flour was kept constant (15%) in every sample (Table 1). Small amount of milk flavor was added for reducing the odor of mushroom and improving the taste.

Method of analysis
Proximate analysis
The proximate analysis of the mushroom fortified floursuch as (moisture, ash, protein, fat and fibre) was done according to the standard analytical methods [15]. The carbohydrate content was measured by calculated difference method [100-(moisture+ ash+ protein+ fat+ fibre)] and energy content was estimated by multiplying the amount of fat, protein and carbohydrate by their respective physiological energy values (9 kcal for fat, 4 kcal for protein and carbohydrate each) and taking the sum of the products [16].

Sensory analysis
The organoleptic test of the products was done by the 9-point hedonic scale scorecard, especially prepared for the purpose [17-18]. A 10-member trained panelist was selected from the staff members of the Institute of Food Science and Technology (IFST), Bangladesh Council of Scientific and Industrial Research (BCSIR), Bangladesh. Each attribute was scored based on its intensity scaled on a 9-point hedonic scale (1 = disliked extremely, 2 = disliked very much, 3 = disliked moderately, 4 = disliked slightly, 5 = neither liked or disliked, 6 = liked slightly, 7 = like moderately, 8 = liked very much, 9 = liked very extremely) for color, flavor, texture, and taste.

Statistical analysis
Data analysis was performed using Statistical Package for the Social Sciences (SPSS version 15.0 SPSS Inc. Chicago, Illinois, U.S.A). Values were expressed as percentage and mean ± SD. One way ANOVA was used for determining the significance of results. Means were separated using t-test.

Proximate compositions of mushroom flour and Oat flour (on dry basis)
In the present study, the moisture, ash, protein, fat, crude fibre, carbohydrate and energy of the mushroom flour were found 4.06%, 7.26%, 33.14%, 2.06%, 12.56%, 44.98%, 331 Kcal/100g respectively on dry weight basis. These results are almost similar with the study Farzana and Mohajan [19]. The proximate composition, i.e. moisture, ash, protein, fat, crude fibre, carbohydrate and energy content of the oat flour were found 8.01%, 1.95%, 16.28%, 3.54%, 2.45%, 75.78%, 400Kcal/100g respectively on dry weight basis. These results are almost similar to the findings of Youssef, M. K. E., et al. [20].

Proximate composition and mineral analysis of developed flour formulated with different levels of mushroom flour and oats flour (on dry basis) Mushroom fortified flour with different levels of mushroom flour was prepared and their proximate and mineral analysis was carried out. These results were shown in the Table 2 (on dry basis).

In this study, the moisture were ranged from (10.66 to 10.13%), ash (0.69 to 1.26%), protein (14.04 to 16.49%), fat (2.85 to 2.02%), fiber (1.0 to 0.97%), carbohydrate (81.39 to 79.26%) and energy (407 to 401 kcal/100g). Ash, protein contents were linearly increased with the increasing percentage of mushroom flour (Table 2). These trends of increase are in agreement with the study of Genenu., et al. 2017 [21]. The highest ash and protein content was found for F₃ (1.26% and 16.49%) while least for control F₀ (0.69% and 14.04%).

The highest moisture content was found for control F₀ (10.66%) while least for F₃ (10.13%). The moisture content for other treatments F₁ and F₂ was found 10.44% and 10.28% respectively. The highest fat content was found for control F0 (2.85%) while least for F₃ (2.02%). The fat content for other treatments F₁ and F₂ was found 2.24% and 2.15% respectively. The highest fibre content was found for control F₀ (1.00%) while least for F₃ (0.97%). The fibre content for other treatments F₁ and F₂ was found 0.99% and 0.98% respectively. The highest carbohydrate content was found for control F₀ (81.39%) while least for F3 (79.26%). The carbohydrate content for other treatments F₁ and F₂ was found 81.03% and 80.01% respectively. The highest energy content was found for treatment, control F₀ (407 Kcal) while least for F₃ (401 Kcal). The energy content for other treatments F₁ and F₂ was found 403 Kcal and 402 Kcal respectively.

The mineral contents (sodium ranged from 773.51 to 1226.54 mg/100g, potassium ranged from 1213.02 to 3388.78mg/100g, calcium ranged from 103.41 to 132.00 mg/100g, iron ranged from 6.97 to 15.85 mg/100g and manganese ranged from 11.18 to 16.54 mg/100g) were increased with the increasing content of mushroom flour (Table 3). Similar increasing trends were also observed in other studies Stella., et al. 2015 [22].

The highest sodium (Na) content was found for sample F₃ (1226.54 mg/100g) while least for control, F₀ (773.51 mg/100g). The sodium content for other treatments, F₁ and F₂ was found 856.37mg/100g and 1097.47mg/100g respectively. The highest potassium (K) content was found for sample F₃ (3388.78 mg/100g) while least for control, F₀ (1213.02 mg/100g). The potassium content for other treatments, F₁ and F₂ was found 3130.75mg/100g and 3258.39mg/100g respectively. The highest calcium (Ca) content was found for sample F₃ (132.00 mg/100g) while least for control, F₀ (103.41mg/100g). The calcium content for other treatments, F₁ and F₂ was found 116.39mg/100g and 123.04mg/100g respectively. The highest iron (Fe) content was found for sample F₃ (15.85 mg/100g) while least for control, F₀ (6.97 mg/100g). The iron content for other treatments, F₁ and F₂ was found 7.73mg/100g and 9.46mg/100g respectively. The highest manganese (Mn) content was found sample F₃ (16.54 mg/100g) while least for control, F₀ (11.18 mg/100g). The manganese content for other treatments, F₁ and F₂ was found 15.24mg/100g and 15.60mg/100g respectively. Heavy metals such as Cu, Cd. Pd, Al, Pb, Cr were not found in the prepared samples. Thus by incorporation wheat flour with mushroom and oat flour has improved the nutritional quality of the flour.

Sensory analysis
In the present study, sensory scores of roti prepared with developed mushroom flour enriched with 5% (F₁), 7% (F₂), and 10% (F₃) mushroom flour keeping the oat flour percentage constant at 15%, showed that with regard to flavor, taste, texture, color, mouth feel and overall acceptability, the sensory characteristics of F₁ (5%) were found to be the best among F₀ (0% control), F₂(7%) and F₃(10%). (Table 4)

The score for color has decreased from 8.8 to 7.6 with the increase of mushroom flour. Taste of any product is considered as the primary concern when it comes to the possibility of successful acceptance in the local market. The taste score was highest for F1 (5%) while F0(0% control) and F2 (7%) was also in acceptable range but F3(10%) taste score was lower due to high mushroom flour content.

The texture of any product is related to the external appearance that is softness or hardness of the product. F0 (0% control) and F1 (5%) was found to score on the basis of texture and external appearance. But F2 and F3 scored lower than F0 and F1. Flavor of the product was highest for F1(5%). Mouth feel was in acceptable limit for both F0 and F1. But with the increase of the percentage of mushroom flour the mouth-feel decreased. Overall acceptability includes many implications, which is an important parameter in organoleptic estimation. Treatment F1 that is 5% mushroom flour had the highest mean value (8.2) for the overall acceptability. The overall acceptability for F0 (0% control) has a mean score of 8.0 very close to F1 (5%). Above this level, flour received a lower sensory score. Thus 5% mushroom flour has highest scores for all the sensory attributes evaluated.

Comparison of proximate composition of newly developed mushroom fortified flour with locally available flours is as described below (on a dry basis)
Comparison of proximate analysis of developed mushroom fortified flour and locally available wheat flours are shown in table 5

Moisture content
In this present study, moisture content of newly developed mushroom flour was found 10.44% where moisture content of local flour was ranged from 11.59% to 12.48%. The moisture content of the developed mushroom flour was a little lower than local wheat flour. This could be because of dried mushroom flour contains lower moisture which ultimately lower the moisture content. Moisture content is the most important factor to control microbial growth. The study of Muhammad., et al. describes that, moisture content less than 10% is suitable to maintain the quality of dried food materials [23].

Ash content
The ash content of the Mushroom flour was found 1.01% which is higher than other wheat flour available in local market. This may be due to presence of mushroom flour and oat flour content [24]. Higher mineral content will make this flour a better choice than other local wheat flours.

Protein content
The protein content was found 14.72% that is higher compared to locally available flours. This increase in protein content may be due to the presence of mushroom fortification [25-26]. Thus regular consumption of this flour will be helpful to overcome protein-calorie malnutrition of the people.

Fat content
In the present study, the fat content was found 2.24%. That was little higher than the fat content found in local flour. The fat content was a little due to the presence of mushroom flour [27].

Fibre content
The fibre content of the mushroom flour was found to be 0.99% where fibre content of local flours were ranged from 0.07-0.15%. This higher fibre content could be explained as mushroom flour contains higher amount of fibre [28]. Regular flour do not contain high amount of fibre as the fibre is removed during processing. So the addition of fibre using mushroom flour will be helpful in many ways. Dietary fibre contains many health benefits such as prevention of diabetes diverticulitis, cardiovascular diseases, constipation, irritable colon cancer etc. [29-30].

Carbohydrate and energy content
In the present study, carbohydrate and energy content was found 81.03% and 403kcal. Carbohydrate that was lower than the locally available flour. The lower carbohydrate content makes it suitable to consume for all ages of people. The energy value in the present study was found 403kcal per 100g which was slightly lower than other local flour. This may be due to the lower fat content.

Iron Content
The iron content was found 7.73mg/100g that is higher compared to locally available flours. This increase in iron content may be due to the presence of mushroom flour. Thus regular consumption of this flour will be helpful to overcome iron deficiency and it will help to improve hemoglobin deficiency of the people.

From the above studies, it can be stated that fortification of wheat flour with mushroom and oats flour has significant effects on the nutritional, physical and sensory attributes. Depending on the nutritional and sensory results, it can be concluded that flour fortified with 5% mushroom and 15% oats isacceptable in quality and it is nutritionally superior over locally available flours.The findings of the present study will be helpful for the people suffering from malnutrition and other degenerative diseases. Using this flour in bakery will also help to add some nutritional value to the finished products.

Conflict of interest
No conflict of interest