ABSTRACT
The study determined the nutrient composition of wild and cultivated edible mushrooms, and explored their use of cultivated Pleurotus tuber-regium in food-to-food fortification. Wild edible mushrooms (Pleurotus tuber-regium, Pholiota mutabilis, Pleurotus ostreatus, Corprinus disseminates, and Peziza badioconfusa Korf) were collected from different parts of the University of Nigeria, Nsukka (UNN) residential quarters and identified in the Department of Botany, UNN. Cultivated Pleurotus tuber-regium was collected from the Department of Botany, UNN. The wild and cultivated mushrooms were processed into flour and chemically analyzed using standard methods of analysis. Different proportions (20g, 40g and 60g) of the Pleurotus tuber-regium flour were incorporated into 600g of wheat flour, cocoyam paste and corn starch to produce composites. The composites were used to prepare the following snacks: wheat buns, cocoyam buns and aged jollify. Each of these snacks had their controls made without mushroom. Sensory evaluation of the snacks was conducted using 20 panelists (children aged 8-14 years). The evaluation was done in three days at the rate of one fortified food (snack) per day. A 9-point Hedonic scale of 9 (highest) to 1 (lowest) was used to evaluate the products. The nutrient composition of the snacks was calculated using available food composition Tables as well as the nutrient composition of the cultivated Pleurotus mushroom obtained in the study. The percentage increase in specific nutrients as a result of fortification was calculated. The ability of the most acceptable snacks in meeting some specific nutrient requirements of pre-school and school children was determined using recommended nutrient intakes (RENI) for energy, protein, vitamins and minerals. Data were analysed using one way analysis of variance (ANOVA). Significance was accepted at p<0.05, Duncan’s new multiple range test was used to separate means.
The wild and cultivated mushrooms were high in protein (10.1 to 33.0% wet weight), but low in fat and crude fiber (<1% and <2% respectively). Calcium varied from 86.2 mg/100g to 372.3 mg/100g. All the wild and cultivated mushrooms contained good amounts of selenium from 11.3 µg/100g to 48.7 µg/100g, except Pholiota mutabilis which had 1.9µg/100g. Copper varied from 32.7 µg/100g to 199.4 µg/100g. Folic acid ranged between 1235.0 µg/100g and 2484.0 µg/100g, vitamin B12 from 1.85 mg/100g to 4.33 mg/100g and vitamin E from 16.28 mg/100g to 33.40 mg/100g. Thiamin varied between 0.04 mg/100g and 0.90 mg/100g, riboflavin from 0.13 mg/100g to 0.36 mg/100g and vitamin C, from 0.20 mg/100g to 9.7 mg/100g. There were no significant (P>0.05) differences in the organoleptic attributes of samples containing mushroom and those not containing mushroom except for texture of cocoyam buns fortified with 40g mushroom (CBM40) which was significantly (P<0.05) different from the control. In wheat buns fortified with 60g mushroom flour (WBM60), protein increased by over 20%, copper by over 700%, selenium by over 50%, folic acid by over 130% and vitamin E by over 230%. There were slight increases in calcium (19.6%), iron (2.8%), vitamin C (32.1%), thiamin (5.0%), riboflavin (16.7%) and niacin (5.3%) with addition of mushroom. For pre-school children (PSC), 100g of the wheat buns fortified with 60g mushroom (WMB60) contributed 268.6% selenium, 180% folic acid, 563.6% vitamin B12 and 43.1% vitamin E of RNI. Wheat buns fortified with 60g mushroom (WBM60), provided 66.5% and 42.9% of the recommended protein intakes of pre- school and school children, respectively. Agidi jollof fortified with 60g mushroom flour (AJM60) had high increases in folic acid (374.7%), vitamin E (281.1%), vitamin B12 (77.8%) and selenium (61.1%) contents over the control. AJM60 furnished the following percentages of the requirements of pre-school children: Selenium (31.4%). folic acid (63.6%), vitamin B12 (90%) and vitamin E (31%). For school children, AJM60 furnished 26.9% selenium and 38.2% folic acid. Cocoyam buns fortified with 60g mushroom (CBM60) had marked increases in selenium (91.5%), copper (104.4%), folic acid (714.9%), niacin (34.5%) and vitamin E (208.0%) over control. CBM60 contributed 24.4% of selenium, 47.3% of vitamin B12, 96.0% of folic acid and 12.0% of vitamin E to the RNI of pre-school children. For school children, CBM60 provided 21.0% of selenium, 29.0% of vitamin B12, 9.0% of vitamin E and 57.3% of folic acid. Wild or cultivated Pleurotus tuber-regium is indeed a highly nutritious food that can contribute to sustainable diets of various population groups. The fortified products could be promoted in place of empty-calorie and other fast foods that are almost replacing the traditional foods.
1.0 Background of the Study
INTRODUCTION
CHAPTER ONE
Food insecurity remains a significant international problem, with developing regions of the world enduring most of the burden. Food insecurity results in considerable health, social, psychological and behavioural consequences and is undeniably linked to poverty. Despite international commitment, the number of food insecure individuals remains unacceptably high (Bandies University, 2000). There is lack of sustainable physical and economic access to enough, safe, nutritious and socially acceptable food for a healthy and productive life all over the world, and in Nigeria in particular at national and household levels (Aliyu, 2005). In Nigeria, as in many developing countries, malnutrition is caused by many factors among which is the long standing moderate food shortage coupled with sub-optimal use of traditional food sources.
Traditional foods were defined by Kuhnlein and Recevour (1996) as food from a particular culture available from local resources and culturally acceptable as appropriate and desirable foods. Traditional plant foods have also been defined as those plants which are accepted by a community through customs, habit and tradition as appropriate and desirable foods. They are grown for food within the farming system in any particular locality or gathered in wild or semi wild condition. They can be divided into two groups: those consumed as traditional dietary staples and those consumed as components of accompanying relishes and sauces. They include a large variety of legumes, oils seeds, fruits and vegetables (FAO, 1995). Kuhnlein (2003) also reported that traditional foods contain a wealth of micronutrients that have been poorly described and reported in scientific literature. Understanding the micronutrient contents of species in our traditional food system would be an essential step towards the goal of building health promoting activities that could incorporate these foods into commonly used staples, thereby alleviating micronutrient malnutrition that constitute the most wide spread form of malnutrition in the world.
In Nigeria there are lots of cheap nutritious and readily available food crops (e.g. mushroom) which could be adequately processed and used as food fortificant to improve the already existing recipes such as porridges, snacks or even soups. Nutrition transition is taking place very much faster and in some cases with extreme rapidity (Reddy & Yusuf, 1998). The nutrition transition is marked by a shift from relatively monotonous diets based on indigenous staples towards more varied diets that include more preprocessed food, more food of animal origin, processed drinks and foods. This is inevitable consequence of urbanization. The effect of relatively dense diet and physical inactivity has increased the incidence of obesity and other diet related chronic diseases (Reddy & Yusuf., 1998).
Our locally available food sources of micronutrients should be given priority in order to achieve an improved nutrition which is one of the Millennium Development Goals. It was recognized by FAO (1995) that fortication of food could in certain situations be an essential component of food-based approach of eradicating micronutrient malnutrition. Food fortication is the public health policy of adding micronutrients to foodstuffs to ensure that minimum dietary requirement are met.
Fortification of food has been defined as the addition of one or more micronutrients to foodstuff (vitamins, protein or amino acids and minerals) whether or not it is normally contained in the food, for the pupose of preventing deficiency of one or more nutrients in specific population groups. Processed simple diets based on staple foods could be fortified by some traditional food sources that are very rich in important micronutrients. Dietary diversity especially from indigenous food sources appears to be one of the food-based approaches to meeting the nutrient requirement of the teaming population worldwide. Addition of micronutrient rich traditional food soruces to known recipes of staple foods could prevent large-scale deficiency disease.
Food fortification could be done to:
– replace losses that occur during manufacture, storage and handling of food to ensure nutritional equivalence in substitute.
– compensate for naturally occurring variations in nutrient levels.
– provide levels higher than those normally found in a food.
– provide a balanced intake of micronutrients in special cases (dietetic foods).
The FGN/UNICEF (2004) consultation group on food fortification considered various types of methods for forticiation.
i. Food to food
ii. Single nutrient to food
iii. Double or multiple fortification (Nnanyelugo, 1999)
The mushroom is the visible fruiting body of a fungus which emerges from underground mycelium during certain seasons of the year. The mycelium usually hides
under bark, ground, rotten wood and leaves. The mushrooms belong to the class basidiomycetes and subclass Homobasidiomycetidoe. Mushroom can be gathered in wild form or cultivated. The essential difference between the wild and cultivated mushroom is that the former bears their spores in groups of fours, while the latter usually bears their spores in twos (Atkins, 1996). Mushrroms are saprophytes and live on dead matters.
Edible mushrooms have high protein content and are excellent sources of fiber, B-complex vitamins, including riboflavin (B2) biotin, folate, vitamin B12, pro-vitamin D, vitamins E and K and a small amount of vitamin C (Qutila, 1999). Dubost (2005) also enumerated some minerals contained in the mushroom such as selenium, copper, potassium, phosphorus, zinc, manganese, iron, magnesium and calcium, all in variable amounts.
Today foods of fungal origin are consumed all over the world in vast quantities and commercial production is part of a rapidly growing industry. Fungi have excellent value nutritionally and are of great importance to vegetarians. Fungus has been influencing human affairs for thousands of years, whether as a direct food soruces, as a medicine or in a food process (Carlile & Watkinson, 1994). Mushroom being one of fungi origin with valuable micronutrients, need to be incorporated into our diet to help reduce the problem of micronutrient malnutrition (hidden hunger) and non communicable diseases.
Research suggest that mushroom may aid in the treatment of certain types of cancer, boost immune system and reduce the risk of coronary heart disease (CHD) like vegetables, muchrooms are a cholesterol free food. This is promising, as cholesterol is regarded as a risk factor of coronary heart disease and related conditions (Carlile & Watkinson, 1994). A study carried out by Fukushima (2000) reported that mushroom in Basidiomycotina had the ability to lower serum cholersterol concentration. Cheung (1998) also described mushroom as an ideal food for the prevention of artherosclerosis due to their high fiber content. This study concluded that inclusion of edible mushroom into the diet has a hypocholesteroldemic effect perhaps due to dietary fiber such as B- glucans which may increase intestinal mortality, reducing bile acid and cholesterol absorption. Unfortunately the use of mushroom as food has not been fully exploited.
The purpose of this study is to determine nutrient poterntials of traditional wild and cultivated edible mushrooms and their possible use in fortifying snacks for pre- school and school children.
1.1 Statement of the Problem
Micronutrient malnutrition or hidden hunger coupled with protein energy malnutrition (PEM) have remained a serious public health problem in many developing countries, including Nigeria (WHO, 1998). Micronutrient malnutrition occurs in the face of adequate energy and protein intake. Deficiencies in vitamin A, iron and iodine cause innumerable maternal and childhood deaths and leave millions of survivors blind or mentally retarded. Even less severe deficiencies impair intelligence and strength reducing working capacity, productivity and impending economic development (Laurian, Carl & Robert, 2007). Millions of people worldwide suffer from hunger and malnutrition. A major factor contributing to this international problem is food insecurity. In Nigeria two thirds of the population live below poverty line and household food security, quality of care, health services as well as environmental sanitation are inadequate. Numerous studies based on analysis of anthropometric data from chidlren in various parts of nigeria have shown high prevalence of household food insecurity and manultrition. The Nigerian Demographic and Health Survey (NDHS, 2008) revealed that 38% of chidlren under give years of age are stunted, an indication of chronic household food insecurity. This survey also found out that the proportion of underweight chidlren to be 29% which is attributable to transitory food insecurity. This is as a result of lack of knowledge of the nutritional adequacy of various traditional food resources (Agari, 1992). One of such food is the mushroom which is among the most neglected and underutilized foods in the Nigerian food system. The potential resources are good but, organizations, control and usage of these resources have been poor (Onyezili, 2005). Examples of such neglected plant foods include edible mushrooms. Consumption of mushroom has been negatively affected by misconceptions, superstitious belief, culture, religion, ignorance of their nutritional value and personal food preferences as well as deforestation, and flood (Agari, 1992). There is dearth of information on wild and cultivated edible mushroom in Nigeria. It has also been observed that mushroom have not been fully exploited in the alleviation of micronutrient malnutrition, hence this study. Nutrition transition which is marked by a shift from relatively monotonous diet based on indigenous staples towards more varied diet, is taking place vary much faster. It involves a shift towards preprocessed foods; more of animal origin, processed drinks and foods (Reddy & Yusuf, 1998). Traditional food sources are abandoned for more “modern” foods, when it is desirable to use the traditional foods to improve the more “modern” foods. Examples of such neglected plant foods include edible mushrooms. Consumption of mushroom has been negatively affected by misconceptions, superstitious belief, culture, religion, ignorance of their nutritional value and personal food preferences as well as deforestation, and flood (Agari, 1992). There is dearth of information on wild and cultivated edible mushroom in Nigeria. It has also been observed that mushroom have not been fully exploited in the alleviation of micronutrient malnutrition, hence this study.
1.2 General Objective
The general objective of this study was to identify and determine the nutrient potential of wild and cultivated edible mushrooms and evaluate their possible use as food fortificants.
1.3 Specific Objectives
The specific objectives were to:
i. harvest and identify wild edible mushrooms;
ii. determine the nutrient composition of the edible mushrooms;
iii. identify the photochemicals in the mushroom that would be used as food fortificant;
iv. incorporate mushroom flour into snacks in order to enrich their nutrient profile;
v. determine their nutrient composition as well as the organoloptic qualities of these enriched/fortified products; and
vi. determine their ability to met RNI of specific nutrients for pre-school and school children.
1.4 Significance of the study Good nutrition is necessary to achieve a healthy active life, optimum educational performance and enhanced productivity. In order to achieve the Millennium Development Goals, it becomes necessary that our common staple and preprocessed foods be fortified with readily available cheap traditional foods that have been identified as good sources of essential micronutrients. Mushroom being one of such foods is cheap and affordable especially to consumers who dwell in the rural areas. The result of this study will provide the much needed information for different wild and cultivated edible mushrooms thereby enhancing the consumption of this valuable food and increased consumption will lead to increased cultivation/production and reduction in micronutrient malnutrition which is wide spread in Nigeria as well as other developing countries of the world. The result of this study will also be relevant to researchers who intend to conduct further research on mushroom. Dieticians, nutritionist and health educators will benefit from this study because this would provide information on the nutrient composition of edible mushrooms and the knowedge will help them to councel
This material content is developed to serve as a GUIDE for students to conduct academic research
NUTRIENT POTENTIAL OF WILD AND CULTIVATED EDIBLE MUSHROOMS AND THEIR POSSIBLE
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