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TOMATO CONCENTRATE PRODUCTION USING MINIMALLY PROCESSED APPROACH AND A SIMPLE DESIGN SEPARATION DEVICE BY OKON,ANIEBIET WILLIAMS 05/EG/FE/091 SUBMITTED TO THE DEPARTMENT OF AGRICULTURAL AND FOOD ENGINEERING FACULTY OF ENGINEERING UNIVERSITY OF UYO, UYO AKWA IBOM STATE IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF BACHELOR OF ENGINEERING (B. ENG) DEGREE IN FOOD ENGINEERING MARCH, 2012 CERTIFICATION This is to certify that this project is the original work of OKON, ANIEBIET WILLIAMS; with Reg No; 05/EG/FE/091 carried out under the supervision of Engr E. Ekpenyong of the department of Food Engineering, Faculty of Engineering , University Of Uyo, Uyo. OKON, ANIEBIET WILLIAMS DATE Student ENGR. E. EKPENYONG DATE Project Supervisor DR. A. F. ALONGE DATE Head of department PROF. (MRS) K. A. TAIWO External Examiner DATE DEDICATION This work is dedicated to my Mother, Mrs. Anthonia Williams Umoh, for all the sacrifices she has made for me to be who I am today. ACKNOWLEDGEMENT I am highly thankful to my project supervisor, Engr. E. Ekpenyong, for his encouragement and guidance towards the success of this work. My sincere gratitude goes to my parents, Evang and Mrs. Williams Okon Umoh, for their foresight that education is the key to success and putting me on that platform. My appreciation equally goes to my good friends, Aniebiet, Enobong and Patience, for their effort and support. I am greatly indebted to my siblings; Nkereuwem, Ofonmbuk, Mfon, Imo, Udeme, Idongesit and Nsikak for their love, understanding and sacrifice towards my education. I sincerely thank my lecturers and fellow students, for supplying me with useful materials for this work. My appreciation also goes to Mr. N. E. Etuk, the Food Engineering laboratory Technologist, for his assistance throughout the research work. A special thank u to my precious son, Harmony Imo Nkweini, for being such a wonderful child even with my hectic schedule. Above all, I sincerely thank God Almighty, for his providence which has made this dream realizable and my life a success. TABLE OF CONTENT Content Title -- Pages -- -- -- -- -- -- -- -- -- i Certification -- -- -- -- -- -- -- -- -- ii Dedication -- -- -- -- -- -- -- -- -- iii Acknowledgement -- -- -- -- -- -- -- -- iv Table of content -- -- -- -- -- -- -- -- v List of tables -- -- -- -- -- -- -- -- -- viii List of figures -- -- -- -- -- -- -- -- -- viii Abstract -- -- -- -- -- -- -- -- -- ix INTRODUCTION -- -- -- -- -- -- -- -- 1 CHAPTER ONE 1.1 Statement of Problem -- -- -- -- -- -- 3 1.2 Objective of the Study -- -- -- -- -- -- 3 -- -- -- -- -- -- 4 CHAPTER TWO LITERATURE REVIEW -- -- 2.1 Consumption of Tomatoes -- -- -- -- -- -- 6 2.2 Nutrition -- -- -- -- -- -- -- -- 7 2.3 Preservation -- -- -- -- -- -- -- -- 10 2.4 Minimal -- -- -- -- -- -- -- -- 11 2.5 Water Activities -- -- -- -- -- -- -- 12 2.5.1 Importance of Water Activities -- -- -- -- -- 12 2.5.2 Predicting Food Spoilage -- -- -- -- -- 13 2.5.3 Water Activity and Moisture Control -- -- -- -- -- 15 2.5.4 How Water Activity can be Controlled -- -- -- -- 15 -- CHAPTER THREE MATERIALS AND METHODS 3.1 Experimental Materials -- -- -- -- -- -- 19 3.1.1 A Simple Filtering Device -- -- -- -- -- -- 19 3.2 -- -- -- -- -- -- 21 3.2.1 Weight Determination -- -- -- -- -- -- 21 3.2.2 Size Reduction -- -- -- -- -- -- 21 3.2.3 Moisture Content Determination -- -- -- -- -- 21 3.2.4 pH Determination -- -- -- -- -- -- 22 3.2.5 Determination of Flux -- -- -- -- -- -- 22 3.2.6 Colour Determination -- -- -- -- -- -- 23 -- -- -- -- -- -- 24 Experimental Proceedings 3.2.7 Packaging -- -- -- -- CHAPTER FOUR RESULTS AND DISCUSSION -- -- -- -- -- -- -- 25 4.1 -- -- -- -- -- -- -- 25 4.1.1 Moisture Content -- -- -- -- -- -- -- 25 4.1.2 pH Level -- -- -- -- -- -- -- 26 -- -- -- -- -- -- -- 33 CONCLUSION AND RECOMMENDATIONS -- -- -- -- -- 36 5.1 Conclusion 5.2 Results -- -- 4.1.3 Colour Content CHAPTER FIVE -- -- -- -- -- -- -- -- 36 Recommendations -- -- -- -- -- -- -- 37 References -- -- -- -- -- -- -- 38 -- APPENDIX Appendix A: Moisture Content Determination -- -- -- 41 Appendix B: Calculation of Tomato Colour -- -- -- 45 Appendix C: Flow Rate Calculation -- -- -- 46 -- LIST OF TABLES Table 2.1: Nutritional content of tomato fruits -- -- -- 9 Table 2.2: Water activity values of microorganism’s inhibition -- -- 14 Table 2.3: Water activity of some food stuffs -- -- Table 4.1: Moisture Content of Tomato Concentrate -- -- -- -- 17 -- -- -- 25 Table 4.2: Variation in pH with period of preservation and concentration of salt (Sample A) -- -- -- -- -- -- -- -- 26 Table 4.3: Variation in pH with period of preservation and concentration of salt (Sample B) -- -- -- -- -- -- -- -- 28 Table 4.4: Variation in pH with period of preservation and concentration of salt (Sample C) -- -- -- -- -- -- -- -- 30 -- -- 33 Figure 1: Plot of pH against period of preservation (Sample A) -- -- 27 Figure 2: Plot of pH against period of preservation (Sample B) -- -- 29 Figure 3: Plot of pH against period of preservation (Sample C) -- -- 31 Figure 4: Change in Colour against Period of Preservation -- -- -- 34 Figure 5: A simple fabricated filtering device Table 4.5: Variation in colour with period of preservation LIST OF FIGURES -- -- -- -- 47 Figure 5: Various Components of the Filter Device -- -- -- -- 48 ABSTRACT This study was based on the production of tomato concentrate from tomato fruit using minimally processed approach and a simple design separation device. The tomato fruits were processed and preserved with no application of heat rather a simple filtering device was fabricated for the dewatering of the tomato slurry. After extraction, the tomato paste was analyzed for its pH and colour. The tomato concentrate was preserved using salt and vegetable oil only, the analysis was for the moisture content, flux, surface area of the filter as it affects the rate of filtration, the quality of water filtered out to check any nutrient loss, colour and the pH of the slurry, filtrate and concentrate. It was carried out with variations in the concentration of salt for three samples and the results obtained indicated that the salt concentration, quantity of vegetable oil and water activity were the major factors that affected the shelf life of the product. The colour was 500Hazen Units for the fresh and there was no change in colour observed physically for eight weeks of preservation but only a slight change at 430Hazen units at eight weeks when observed using a colour comparator. There was no change in taste or texture after eight weeks of preservation and this suggests that preservation of tomato with salt is very effective and healthy. CHAPTER ONE INTRODUCTION Tomato (Solanum lycopersicum) is a popular fruit consumed in most part of the world. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler climates. The tomato fruit is consumed in diverse ways, they are consumed as fresh product as well as processed product such as canned whole tomato, tomato juice, tomato paste, ketchup and chill sauce. (Chalmore and Roman, 1971). The tomato fruits are red or yellowish berry which vary in diameter from 1.5 to 7.5cm and shape from almost spherical through oval and elongate to pear shape. While it is botanically a fruit, it is considered a vegetable for culinary purposes. Tomato has great nutritional values, the tomato juice is known to contain vitamin C, sugar, and mineral (Broody, 1997). The fruit is rich in lycopene which has beneficial health effects. . The tomato is now grown worldwide for its edible fruits, with thousands of cultivars having been selected with varying fruit types, and for optimum growth in differing growing conditions. The ripe tomato fruit contains approximately 93.5% of water, 1.1% protein, 0.3 of fat, 4.7% carbohydrate and 0.5% Ash (Singh, 1993). Most tomato varieties have 4.5 to 7.8% soluble solid, much of it as fructose or glucose. The pH of tomatoes is about 4.2 and for processing, it should be below 4.6 to prevent spoilage (Robinson, 1997). Citric acid is the predominant acid in tomato juice. Glutei acid is the main amino acid present in tomato and it is rarely found in other fruits. Methioninie and 5 methyl methionie are also present. There are many varieties of tomato such as amateur, dwarf, money maker, etc. (Anyawu and Adam, 1979). Fruits and vegetables play a very important role in the daily diet as there is a clear interaction between consumption of fruits and vegetables and good health, particular attention has not only been paid to their composition, vitamin content, microelements, antioxidant substances, etc. but also to the consumer demands for more convenient, less processed but simultaneously safer foods and these has accelerated the development of minimally processed formulated foods. (Thomas and Nils, 2002) The combination of factors such as water activity (aw), pH, temperature etc in preserving fruits and vegetables is important and all play a crucial role in improving the shelf life of fresh and processed commodities. The increasing popularity of minimally processed fruits and vegetables has resulted in greater health benefits (Alzamoro et al. 2000). 1.1 STATEMENT OF PROBLEM As soon as any food is harvested, the spoilage process begins, this deterioration may be very slow, as in the case of nuts, but much faster as in the case of fruits and vegetables, it may be so rapid that the food becomes inedible within a matter of days. In the case of tomatoes, spoilage begins as soon as it is harvested; the application of heat during processing to preserve it destroys most of its natural ingredient and freshness. Therefore, there is structure for an attempt for its preservation without heat application. 1.2 OBJECTIVE OF STUDY The objective of this study is to use minimally processed methods in the extraction and preservation of tomato concentrate using a simple fabricated filter device and using common salt and vegetable oil in the water activity reduction procedure to stabilize the product. CHAPTER TWO LITERATURE REVIEW Tomato originated in the Andes mountain region of South America. Early domestication was undertaken by the Native Americans. The first encounter with tomatoes by the Europeans was during a voyage by Cortez, a Spanish explorer when he discovered tomatoes growing in Montezuma’s garden and brought seeds back to Europe where they were planted as ornamental curiosities but not eaten. Though it is considered a native of South America, tomato presently is one of the most important vegetable crops in West Africa (Amy et al., 1968). The tomato was actually taken by the Moors first through Spain and then more widely distributed. The Moors involvement resulted in one of the Europeans names for tomato; Pome dei moro(Moors apple). The earliest European document that referred to tomato were by Italian Petrus, Andreas Mathiolus in 1544 and named a cultivar pomi d’oro meaning ‘golden apple’. The first fruit shape was described as flattened, segmented and of golden color rather than red. In 1554, Mathiolus noted a second variety equivalent in shape but red in color. The previous year in Germany, 1553, George Oelinger (Nerenburg garden) documented the red faciated tomato. He illustrated the tomato plant and fruit in detail and also noted the existence of two yellow varieties. The English word ‘tomato’ comes from the Spanish tomatl first appearing in prints in 1595. A member of the deadly nightshade family, tomatoes were erroneously thought to be poisonous (although the leaves are poisonous) by Europeans who were suspicious of their bright shiny fruit. Native versions were small like cherry tomatoes and most likely yellow in colour rather than red. The French botanist, Tournefort provided the Latin botanical name lycopersicon esculentum to the tomato. It translates to ‘edible wolf peach’, peach because it was round and luscious and wolf because it was erroneously considered poisonous. The botanist mistakenly took the tomato for the wolf peach referred to by Gralen in his third century writings, i.e. poison in a palatable package which was used to destroy wolves. They referred to the tomato as pommes d’amour or love as they thought them to have stimulating aphrodisiacal properties. Tomato is rarely used raw as a salad in the traditional patterns of consumption and much of it produced locally is eaten cooked in local dishes. Furthermore, it has never been in large quantity because of its low storage quality (Amy D.C et al., 1968). Tomato has many uses; it is used as a condiment in soups and stews. In order to guide against it scarcity during out of season supply, tomato fruits have to be converted into puree and canned (Heidelbaugh and Kennel, 1982). An interesting aspect of tomato history is the classic debate; Is the tomato a fruit of Vegetable? The answer to this question depends on who you are asking. By definition, a fruit is the edible plant structure of a mature ovary of a flowering plant usually eaten raw, some are sweet like apples but the ones that are not sweet such as tomatoes, cucumbers, peppers etc. are commonly called vegetables. Botanists claim fruit is a fleshy material that covers a seed or seeds whereas a horticulturists’ point of view would pose that the tomato is vegetable plant. The history of tomatoes has classified it as a poisonous beautiful plant, a tax avoiding fruit and a taxable vegetable. Nonetheless, the tomato is the most wonderful, most popular vegetable in America and enjoyed by millions all over the world. Botanically, a tomato is a fruit: the ovary, together with its seeds, of a flowering plant. However, the tomato has much lower sugar content than other fruits, and is therefore not as sweet. Typically served as part of a salad or main course of a meal, rather than at dessert, it is considered a vegetable for most culinary purposes. One exception is that tomatoes are treated as a fruit in home canning practices: they are acidic enough to be processed in a water bath rather than a pressure cooker as "vegetables" require. Tomatoes are not the only foodstuff with this ambiguity: eggplants, cucumbers and squashes of all kinds (such as zucchini and pumpkins) are all botanically fruits, yet cooked as vegetables. 2.1 Consumption Tomato fruits are used as salads, served as a cooked vegetable used as an ingredient of various prepared dishes and pickled in canning industries. They are used for the preparation of tomato sauces and tomato juices. Fruits and fruit product play a very important role in human nutrition supplying some of the essential substances in the other of food materials that are deficient (Davison et al, 1975). They are important in neutralizing excess base and acidic substances produced in the course of digestion of food materials. They are important sources of mineral elements needed by the body. Tomato fruits constitute one important source of vitamin C (ascorbic acid) which cannot be synthesized by living organism. Tomato is now grown and eaten around the world. It is used in diverse ways, including raw in salads, and processed into ketchup or tomato soup. Unripe green tomatoes can also be breaded and fried, used to make salsa, or pickled. Tomato juice is sold as a drink, and is used in cocktails such as the Bloody Mary. Tomatoes are used extensively in Mediterranean cuisine, especially Italian and Middle Eastern cuisines. They are a key ingredient in pizza, and are commonly used in pasta sauces. 2.2 Nutrition Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart, among other organs. They contain the carotene lycopene, one of the most powerful natural antioxidants. In some studies, lycopene, has been found to help prevent prostate cancer, but other research contradicts this claim. Lycopene has also been shown to improve the skin's ability to protect against harmful UV rays. Natural genetic variation in tomatoes and their wild relatives has given a genetic plethora of genes that produce lycopene, carotene, anthocyanin, and other antioxidants. Tomato varieties are available with double the normal vitamin C (Double rich), 40 times normal vitamin A , high levels of anthocyanin (resulting in blue tomatoes), and two to four times the normal amount of lycopene. Table 2.1: Nutritional content of a Tomato Fruit Red tomatoes, raw Nutritional value per 100 g (3.5 oz) Nutrients Value (per 100g) Energy 74 kJ (18 kcal) Carbohydrates 3.9 g - Sugars 2.6 g - Dietary fiber 1.2 g Fat 0.2 g Protein 0.9 g Water 94.5 g Vitamin A equiv. 42 μg (5%) - lutein and zeaxanthin 123 μg Vitamin C 14 mg (17%) Vitamin E 0.54 mg (4%) Potassium 237 mg (5%) Source: United States Department Of Agriculture (USDA) Nutrient Database (2011) 2.3 Preservation Tomatoes are usually preserved by canning, drying, freezing or pickling. They can also be used in creating fruit spreads like jams, jellies and marmalades (E.L. Andress, 2010). Unprocessed tomato can be stored at room temperature (above 55°C) until they are fully ripen. While it is undeniably important to increase yields of major food crops in many developing countries, an even greater increase in the amount of food available for human consumption could be realized by using appropriate food preservation methods. Most food is preserved through canning, sun drying and dehydration, smoking, curing and fermentation, freezing and refrigeration, use of chemical additives and packaging (P.O.Ngoddy, 1985). During some of these processes, there is a loss in the natural ingredient in food due to the application of heat or the addition of chemicals and some of these techniques such as canning, freezing and refrigeration require sophisticated equipment, their cost is high and they need electricity and or fuel such as oil or gas to provide the energy for running them. In many developing countries of the tropics, electricity is unavailable and the supply unsteady if available (P.O.Ngoddy, 1985). Therefore, the need for a less sophisticated method of preservation and a richer end product arises. 2.4 Minimal Processing Consumers increasingly demand foods which retain their natural flavor, color and texture and contain fewer additives such as preservatives. In response to these needs, one of the most important recent developments in the food industry has been the development of minimal processing technologies designed to limit the impact of processing on nutritional and sensory quality and to preserve food without the use of synthetic additives. In recent years, two consumer driven demands have arisen in the food industry. The first is for the provision of fresher, more natural foods requiring minimal preparation, the second is food safety. To satisfy the first demand for fresh natural foods needing minimal preservation but which nevertheless have a substantial shelf life, minimal processing is becoming popular. Minimal processing is a concept that usually involves substantial processing but results in foods that have a fresh like quality and contain only natural ingredient. A recent over view identifies two purposes for minimal processing (Ohlsson and Bengtsson, 2002); 1. Keeping the produce fresh yet supplying it in a convenient form without loss of nutritional quality 2. Keeping the shelf life sufficient to make distribution to the consumer feasible. 2.5 Water Activity (aw) Water in food which is not bound to the food molecules can support the growth of bacteria, yeasts and molds (fungi). The term water activity (aw) refers to this unbound and available water. The water activity of a food is not the same thing as its moisture content (Scott, 1953). Although moist foods are likely to have greater water activity than dry foods, this is not always the case. A variety of foods may have exactly the same moisture content and yet different water activities. 2.5.1 Importance of Water Activity (aw) Water activity is one of the most critical factors in determining quality and safety of foods. It affects the shelf life, safety, texture and flavor of food. It is also important to the stability of pharmaceuticals and cosmetics. While temperature, pH and several other factors can determine how fast organisms will grow in a product, water activity may be the most important factor controlling spoilage. Most bacteria, for example, do not grow at water activities below 0.91 and most moulds cease to grow at water activity below 0.80. By measuring water activity, it is possible to predict which microorganisms will and will not be a potential sources of spoilage. It is water activity not moisture content of food that determines the lower limit of available water for microbial growth. In addition to influencing microbial spoilage, water activity can play a significant role in determining the activity of enzymes and vitamins in foods and can have a major impact on the colour, taste and aroma. 2.5.2 Predicting Food Spoilage Water activity has its most useful application in predicting the growth of bacteria, yeasts and molds. For a food to have a useful shelf life without relying on refrigerated storage, it is necessary to control either its acidity level (pH) or the level of water activity or a suitable combination of both. This can effectively increase the products stability and make it possible to predict its shelf life under ambient storage conditions. Table 2.2: Water activity values of microorganism’s inhibition Microorganisms inhibited Water Activity (aw) Clostridium botulinum A, B 0.97 Clostridium botulinum E 0.97 Pseudomonas flourescens 0.97 Clostridium perfringens 0.97 Estherichia coli 0.95 salmoonella 0.95 Vibro chlorerae 0.95 Bacillus cereus 0.93 Listeria monocytogenes 0.92 Bacillus subtills 0.91 Staphylococcus aurens 0.86 Most molds 0.80 Most microbial proliferation 0.50 Source: (Samuel, 1999) 2.5.3 Water Activity and Moisture Content Water is related to moisture content in a non-linear relationship known as a moisture sorption isotherm curve. These isotherms are substances and temperature specific. Isotherms can be used to help predict product stability overtime in different storage conditions. Water activity is defined as the ratio of water vapour pressure of a food product (P) to the vapor pressure of pure water (Po) at the same temperature. Water activity (aw) = P/ Po -- Where -- -- -- -- -- (2.1) P = vapor pressure of water in a substance Po = vapor pressure of pure water at the same temperature 2.5.4 How Water Activity can be controlled Water activity in food can be lowered by removing water from the food, adding solutes that will cause water to bind or lowering the temperature of the product. Removing water means that the remaining water is more lightly bound than before and therefore the water activity is lower. Lowering the temperature results in reducing the rate of movement of the water molecules and this act to lower the water activity. It must be kept in mind that when products warm up, the water activity will rise too and then leave the product prone to whatever negative reactions occur within the new water activity range. Adding solute can result in lowering water activity by lowering the energy state of absorbed water. This is known as forces of adhesion and cohesion (Van der Wall- London forces). Solutes such as sugar or salt lowers the total free energy of the water and therefore ‘bind’ it. The energy that would be needed to remove the bound water from the food is called water potential. Water potential is an equilibrium measure; this means that the water potential is the same throughout the food system. Table 2.3: Water Activity of some food stuffs Type of Product Water Activity (aw) Distill water 1.00 Tap water 0.99 Fresh meat and fish 0.99 Bread 0.95 Aged chedder 0.85 Jams and jellies 0.80 Plum pudding 0.80 Dried fruit 0.60 Biscuits 0.30 Milk powder 0.20 Instant coffee 0.20 Source; International Journal of food science and technology, vol. 42. (2007) Water activity scale extends from 0 (dry bone) to 1.0 (pure water) but most foods have a water activity level in the range of 0.2 for very dry foods to 0.99 for moist fresh foods. Tomato has a water activity of about 0.85. Water activity is in practice usually measure as equilibrium relative humidity. The combination of factors such as water activity (aw), pH, temperature etc., in preserving fruits and vegetables is important and all play a crucial role in improving the shelf life of fresh and processed commodities. The increasing popularity of minimally processed fruits and vegetables has resulted in greater health benefits (Alzamoro et al., 2000). CHAPTER THREE MATERIALS AND METHODS The tomato fruits used for this study were obtained from Akpan Adem market in Uyo, Akwa Ibom state. The samples were bought with no attention paid to its sizes or shape but ensuring that the bad ones were not included, they were manually cleaned with clean water to remove any foreign matter, dust, dirt and the perished fruits. Each tomato fruit was weighed and then sum up to get the total weight. The fruits were then blended using an electric blender to obtain the slurry . The experiment was carried out in the Food Engineering laboratory in Faculty of Engineering, University of Uyo. 3.1 EXPERIMENTAL MATERIALS 3.1.1 A Simple Filtering Device The filtering device used for this study was fabricated. Design Approach In the design and fabrication of a filter device, the following components were involved; Device Components The container: This is the cylindrical section of the filter device that the filter material is attached to and it also contains the tomatoes. It is made from mild steel plates. It has a length of 100mm and 180mm in diameter. The filter material: The filter material used is a synthetic fiber (muslin cloth). This was cut to the diameter of the cylinder with a small allowance for lapping to avoid leakage. The cover: This part of the device was used to cover the container; this is to avoid any foreign material from falling into the tomatoes during filtration. It is 20mm in length and a diameter of 181mm, being slightly wider than the container for proper lapping. It was made from mild steel. The funnel: This the conical section of the filter device made from mild steel plate. It has a length of 120mm and a diameter of 181mm, the extra 1mm is an allowance to insert the container into it. Transparent jar: This part of the device is for receiving the filtrate during filtration. It was purchased. A transparent plastic jar was so that the colour of the filtrate can be observed during filtration to avoid any lost in colour in the tomato concentrate and also to monitor the rate of flow. Tripod stand: This part of the device served as a stand for the filter during filtration. It has a height of 200mm and an inner diameter of an inner diameter of 175mm and outer diameter of 250mm. it was made from iron. 3.2 EXPERIMENTAL PROCEDURES 3.2.1 Weight Determination Each tomato fruit was weighed in batch using the electronic weighing balance by putting it on the balance and obtaining the reading on the screen for all the tomato fruits. The readings were recorded and the total weight taken. The calculation is below; W(avg) = ( w1 + w2 + ------ wn) -- -- -- -- (3.1) n 3.2.2 Size Reduction The tomato fruits were blended using an electric blender until slurry was obtained. They were blended in batches and each batch was preserved in a different container. The total weight of tomato fruits blended for each batch was recorded differently 3.2.3 Moisture Content Determination The tomato slurry was poured into a measuring cylinder and the volume of the slurry for the three samples was taken before filtration. Each slurry sample was filtered using a simple fabricated filtering device; the volume of the filtrate was also measured using the measuring cylinder. After the water has been filtered out, the tomato concentrate was weighed; 5g of tomato concentrate was taken from each of the samples and oven dried at an oven temperature of 105°C to determine the moisture content. The moisture content was determined using the relationship below: Moisture content (% wet weight) = w2 –w3 × 100 w2 –w1 1 -- -- -- (3.2) 3.2.4 pH Determination The pH and/or acidity of a food are generally used to determine processing requirements. An electronic pH meter was used in determining the pH of the tomato paste. A pH water model 3320 JENWAY (electronic) was initially standardized using buffer solution; the electrode was rinsed with distilled water and inserted into the sample. The PH value recorded on the meter scale at a steady point was recorded. 3.2.5 Determination of Flux Flux is defined as flow per unit area, where flow is the movement of some quantity per time. Flux which is the fl ow rate is also the volume of fluid which passes through a given surface per unit time. The flow rate during filtration was about 100ml per hour. The surface area of the filter was determined using the formula below; 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑎 𝑐𝑖𝑟𝑐𝑙𝑒 𝐴 = 𝜋𝑟 2 -- -- -- -- -- -- -- -- (3.3) 3.2.6 Colour Determination Using a Colour Comparator, 10g of tomato concentrate was diluted with distill water, 10ml of distill water was continuously added to the sample until the colour was obtained. 0ne Nessler tube was filled with distill water and another one with the diluted sample. Both tubes were inserted into a colour comparator and the colours compared, the point where there was a colour blend in the two samples was recorded. This was done for the fresh as well as the preserved samples to follow the changes in colour. The point on the disc where there was a blend in colour was multiplied by the number of times diluted to obtain the actual colour. 3.2.7 Packaging The tomato concentrate was stored in a transparent air tight container to prevent any external contaminants from entering and also to be able to see and observe the progress from outside. CHAPTER FOUR RESULTS AND DISCUSSION 4.1 RESULTS The experimental results and discussion from the research are fully presented in this chapter. 4.1.1 Moisture Content Table 4.1: Moisture Content of Tomato Concentrate Weight Sample A B C W1 7.76 7.73 7.92 W2 12.30 11.82 12.58 W3 8.90 8.92 8.9 The moisture content of tomato concentrate was determined before preservation. This was carried out by taking a small sample of each of the samples and drying it at an oven temperature of 105˚C. The weight was constantly checked between 30 minutes interval until a constant weight was attained. 4.1.2 pH Level Table 4.2: Variation in pH with Period of Preservation and Concentration of Salt (Sample A) Qty of tomato Concentrate (g) Salt concentration (g) 0il used (ml) Period of preservation (week) pH 200 11.50 20 0 4.20 1 4.19 2 4.15 3 4.10 4 4.00 5 3.82 6 3.64 7 3.50 8 3.46 4.20 pH of Tomato Concentrate 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40 1 2 3 4 5 6 7 8 Period of Preservation (week) Figure 1: Plot of pH against period of preservation (Sample A) 9 Table 4.3: Variation in pH with period of preservation and concentration of salt (Sample B) Qty of tomato Concentrate (g) Salt concentration (g) Oil used (ml) Period of preservation (week) pH 200 8.50 30 0 4.20 1 4.25 2 4.58 3 4.93 4 5.12 5 5.55 6 5.82 7 6.20 8 6.46 4.60 pH of Tomato Concentrate 4.55 4.50 3.45 3.40 3.35 3.30 3.25 3.20 1 2 3 4 5 6 7 8 Period of Preservation (week) Figure 2: Plot of pH against period of preservation (Sample B) 9 Table 4.4: Variation in pH with period of preservation and concentration of salt (Sample C) Qty of tomato Concentrate (g) Salt Concentration (g) Oil used (ml) Period of Preservation (week) pH 200 10.02 30 0 4.20 1 4.23 2 4.26 3 4.30 4 4.37 5 4.42 6 4.50 7 4.55 8 4.60 6.60 6.40 6.20 pH of Tomato Concentrate 6.00 5.80 5.60 5.40 5.20 5.00 4.80 4.60 4.40 4.20 1 2 3 4 5 6 7 8 9 Period of Preservation (week) Figure 3: Plot of pH against period of preservation (Sample C) Results obtained from analysis in tables above (Tables 5, 6 & 7) indicate that the more the concentration of salt in the tomato concentrate, the more acidic it becomes. This means that for sample A with the pH of 3.46 at eight weeks of preservation, due to the tomato paste becoming more acidic, it is difficult for bacteria to attack, therefore no spoilage has occurred. Sample B indicates a high level of change in the pH at 6.46; it is heading towards neutral which indicates the tomato paste is no longer good for consumption. Sample C shows deterioration at a very slow and steady rate. According to CODEX Alimentarius (1987) standard for processed tomato concentrate, the processed tomato pH must be below 4.6 to achieve an extended shelf without refrigeration. 4.1.2 Colour content Table 4.5: variation in colour with period of preservation Period of Preservation Colour (weeks) 0 500 1 500 2 500 3 490 4 480 5 470 6 460 7 450 8 440 510 500 Colour 490 480 470 460 450 440 1 2 3 4 5 6 7 8 Period of Preservation (week) Figure 4: Change in Colour against Period of Preservation 9 The tomato colour was determined using a color comparator. The result obtained from the fresh tomato was 500 Hazen units; there was no change in colour after three weeks of preservation. The tomato colour after eight weeks of preservation was still reddish and fresh physically with only a slight change when examine using a colour comparator. This colour maintenance is as a result of the vegetable oil and salt keeping the lycopene in the tomato concentrate intact. CHAPTER FIVE CONCLUSION AND RECOMMENDATIONS 5.1 CONCLUSION Tomatoes are a treasure of riches when it comes to their nutritional content; they provide an excellent amount of nutrient as well antioxidant to the body. Keeping the product fresh yet supplying it in a convenient form without loss of nutritional quality can be achieved through minimal processing. This research work has provided the basis for minimal processing of tomato into paste with only salt and vegetable oil as preservatives and the maintenance of its pH as an acid medium and also colour rich in lycopene. Having the rural areas with no electricity in mind, it can concluded that producing and preserving tomato concentrate without heat application or refrigeration is very effective, healthy and safe. It is important to note that the type of tomato fruit used, the concentration of salt and the water activity of the tomato paste are the major factors that affects the safety of the product. 5.2 RECOMMENDATIONS The following recommendations are made from the study; 1. To ensure a better and long lasting product, freshly harvested tomato fruits should be used. 2. To avoid the rapid change in colour, thereby the nutritional value, tomatoes with rich colours should be selected. Deep reds are a great choice. To get the greatest amount of benefit from tomatoes, it is important to choose them carefully. The ripest and reddest tomatoes not only contain the highest amount of lycopene but they are also thought to contain the greatest amount of beta carotene, another vital antioxidant. 3. Determining the water activity of the tomato was a challenge as there is no equipment for measuring it in the food engineering laboratory. For a more accurate result, recommended. using a water activity measuring instrument is REFERENCES Adams, C.F. Ayawu; Nutritive Value of American foods in Common Handwork No. 456. (Washing. D. C.U.S. Government Printing Officer). Ahvenainen R. (1996) “New Approaches in improving shelf life of minimally processed fruit and vegetables”. Trends in food science and Technology 7: pages 179-187, Alzamoro S. M., (2000) A. Lopez Malo and M.S. Tapia etc Daza. “Overview”. In Minimally Processed Fruits and Vegetables. Faundamental Aspects and Application (pp. 1-9) Eds, S. M. Alzamora, M. S. Tapia and A. Lopez Malo. Aspen Publishers; Inc., Gaithersburg, M. D., USA. Brody, J. E. (1997). Tomatoes may be best Vs Cancer new articles home grown Tomatoes. West Palm Beach. USA, Chalmore, D. J. and Roman, K. S. (1971). The Climateric in Ripening Tomato fruit. 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APPENDIX A Moisture Content Calculation Weight Sample A B C W1 7.76 7.73 7.92 W2 12.30 12.23 12.58 W3 8.90 8.92 8.96 % Mc wb = w2-w3 w2-w1 Control Sample Weight of empty beaker (w1) = 7.75 Weight of beaker + sample (w2) = 12.28 Weight of beaker + sample (w3) + 8.98 Using % Mc wb = = w2-w3 w2-w1 × 12.28 - 8.98 100 1 x 100 12.28 - 7.75 = 3.3 4.51 x = 72.85% 1 100 1 Sample A Weight of empty beaker (w1) =7.76 Weight of beaker + sample (w2) = 12.30 Weight of beaker + sample (w3) = 8.90 % Mc wb = w2-w3 w2-w1 x 100 1 = 12.30 - 8.90 12.30 7.76 = 3.4 4.54 = 74.89% * * 100 1 100 1 Sample B Weight of empty beaker (w1) = 7.73 Weight of beaker + sample (w2) = 12.23 Weight of beaker + sample (w3) = 8.92 % Mc wb = w2-w3 w2-w1 × 100 1 = 12.23 - 8.92 12.23 - 7.73 = 3.31 4.5 = 73.56% × × 100 1 Sample C Weight of empty beaker (w1) = 7.92 Weight of beaker + sample (w2) = 12.58 Weight of beaker + sample (w3) = 8.96 % Mc wb = w2-w3 × 100 100 1 w2-w1 1 = 12.58 - 8.96 12.58 7.92 × = 3.62 4.66 = 77.68% Average Moisture Content 100 1 × 100 1 = 72.85+ 74.89+ 73.56+ 77.68 4 = 298.98 4 = 74.75% APPENDIX B Calculation of tomato colour Colour of fresh tomato Ml of standard solution × ml of corresponding factor ml of sample = 10 x 5 0.1 = 500Hazen units APPENDIX C Flow Rate Calculation surface area of the filter = 𝐴 = 𝜋𝑟 2 Diameter of the filter =18cm Radius = 18/2 = 9cm 𝐴 = 𝜋(9)2 =3.14 (81) =162cm Flow rate = volume of the filtrate (ml) Time of filtration (seconds) Volume of filtrate = 250ml Time = 2hrs, 10mins = 4200seconds Flow rate = = 250/4200 0.06ml/s 180 mm 100 mm Figure 5: A simple fabricated filtering device Figure 6: Various Components of the Filter Device: 180mm 20mm Cover 100mm Filter material Container 120mm Funnel Transparent Jar Tripod Stand
