A study to access the pH value of some fresh fruit juices and commercially packaged fruit juices in Uyo metropolis was conducted. Twenty-three (23) fresh fruits samples  were purchased from Itam Market, Uyo Plaza and Traffic Light Junction in Uyo Metropolis for the study. Ten commercially packaged fruit juices were also purchased from the departmental stores in the city of Uyo. The pH value of all the samples was determined using Jenway pH Meter. The weight of all the samples was taken using S-mettler (JA2003) weighing balance. The Fresh Fruits sample considered were: Apple, Avocado pear, Banana, Bitter-kola, Coconut, Coconut-water, Cucumber, Five-finger fruit,  Grape, Kolanut, Lemon, Lime, Mango, Monkey kola (both red and white type), Orange, Pawpaw, Pear, Pineapple, Rose-apple, Tangerine and water-melon. The commercially packaged fruit juices were: Farm pride products (orange, guava) and chivita products (apple, red grape real pineapple). Results obtained showed that variations occur in the pH of the different samples. Of the packaged products, a pH range of 3.0 to 3.8 were obtained for both farm pride and chivita products. Among the fresh fruit, the pH value of lime was the lowest with a value of 1.8 while the values of 3.0 - 5.8 were obtained for the other fresh fruits. This study was therefore conducted to generate the pH value for local fruits with a view to generating data that can be useful guides on fruit intake in health and disease states and also update available fruit data bank information.

Keywords: Data bank, Fresh fruits, Human health, Local fruits and pH values.

Table of Contents

Title page  - - - - - - - - - i

Certification  - - - - - - - - - ii

Dedication    - - - - - - - - - iii

Acknowledgements  - - - - - - - - iv

Abstract  - - - - - - - - - v

Table of Contents - - - - - - - - vi

List of Tables - - - - - - - - - ix

List of Plate  - - - - - - - - - x

Chapter One

1.1. Background Study - - - - - - - 1

1.2. Statement of the Research Problem - - - - - 6

1.3. Objectives of the Study - - - - - - - 7

1.4. Justification of the Study - - - - - - 7

1.5. Scope of work  - - - - - - - - 8

Chapter Two

2.0 Literature Review  - - - - - - - 9

2.1 Introduction/The Concept of pH - - - - - 9

2.2 pH of Fruit Juices - - - - - - - 11

2.2.1 Composition of fruit juices - - - - - - - 12

2.2.2. Charactetics of fruit juices - - - - - - 12

2.3. Fruit Juice Phytochemical Properties - - - - - 13

2.4. Why pH is importance in living system - - - - - 14

2.5. pH and buffering systems in the Body  - - - - - 16

2.6. Effect of pH in management of dental plaque - - - - 19

2.7. Why pH measurement is Necessary - - - - - 20

2.8. Fruit Consumption Trend - - - - - - 20

2.9. Fruit Juice Health Promoting component/Health Benefits - - - 22

2.10. Juice Spoilage and Deterioration  - - - - - 35

2.11. Important Enzymes in Fruit Juice Products - - - - 37

Chapter Three

3.0. Materials and Method  - - - - - - - 38

3.1. Materials - - - - - - - - - 38

3.2. Methods - - - - - - - - - 38

3.2.1 Sample Collection/Preparation - - - - - - 38

3.2.2. Determination of pH values of selected fruit juices - - - 39

3.4 Fruits Under Study - - - - - - - 40

Chapter Four

4.0. Result and Discussion - - - - - - - 43

4.1. Results - - - - - - - - - 43

4.2. Discussions - - - - - - - - 44

Chapter Five

5.1 Conclusion - - - - - - - - 50

5.2 Recommendations  - - - - - - - 51

References  - - - - - - - - 53




Fruits represent an abundant source of nutrients and non-nutritive bioactive compounds which are mostly associated with reduced risk of many non-communicable/chronic diseases (Wolfe et al., 2008). Consumption of fruits and vegetables is important for humanhealth because these foods are primary sources of some essential nutrients and 0contain phytochemicals that may lower risk of chronic disease (DGAC, 2005). Although the botanic term "fruit" refers to the seeds and surrounding tissues of a plant, the foods that are commonly referred to as "fruits" for culinary purposes are pulpy seeded tissues that has a sweet (oranges, apples, pears, blueberries) or tart (lemons, limes cranberries) taste (Pennington and Fisher, 2009).

Fruits are an important component of healthy human diet. They are good sources of vitamins and minerals, vegetable proteins, protective micronutrients and dietary fiberswhich help to prevent constipation (WHO, 2003, Lock et al., 2005 and Balasubramanian, and Ragunathan, 2012). They are foods with energy density, i.e. with few calories in relation to the volume consumed, which favours maintenance of healthy bodyweight (USDA, 2009). Regular consumption of adequate amounts of fruit could prevent major diseases such as cardiovascular disease and some cancers (Pomerleau et al., 2004).

In spite of the enormous benefits of fruits, studies have shown that consumption of fruits in Africa is low compared to the recommended daily intake (Hall et al., 2009). Estimates of fruit in sub-Saharah Africa ranges from 70 to 312g per person per day, far below the WHO/FAO minimum recommendation of 400g per person per day or 146kg per person per year (Ruel et al., 2004). Facts from WHO informationsheet showed approximately 2.7 million of deaths and 1.8% of global disease burden worldwide are attributable to low fruit consumption and insufficient intake of fruit is estimated to cause around 14% of gastrointestinal cancer deaths, about 31% of heart disease and about 11% of stroke deaths (WHO, 2003).

Many people consumed fruit juice on a daily basis. Fruit juices are a convenience way for people to receive the benefits of various fruits. Codex Alimentarius defines juice as "unfermented but fermentable juice intended for direct consumption, obtained by the mechanical process from sound, ripe fruits, preserved exclusively by physical means (FAO, 1992). Properly extracted juices are very similar to the fruit; they contain most substances which are found in the original ripe and sound fruit from which the juice is made. A fruit juice is made from the whole fruit (edible parts) and does not contain more sugar than the corresponding fruit. Recently Ruxton et al., (2006) reviewed the literature comparing health benefits of fruit and fruit juices and concluded that there were no significant differences. The similarities between fruit and fruit juices were also pointed out by Landon (2007).

Pineapple and passion fruit are the most popular juiced todate but others may increase in popularity. The global market for juice products was estimated to be about 50 billion liters in the 1990s (FAO, 1999). Banana juice is made using traditional methods for beer/spirit production but it is not widely sold as juice, most at times it is blended with other fruits juices. In general, juice canalso be made from a mixture of fruits although this is not widely done at present due to high costs involved (Asante and Kuwornu, 2014).

Fruits can be consumed fresh or processed into various forms. Pineapple and mango fruit are the most popular product due to its fruity aroma, fragrance and flavour and is purportedly the most widely consumed fresh fruit in the world with production exceeding 17 million metric tons a year (FAOSTAT, 2007). Mangos are produced in over 90 countries worldwide, Asia accounts for approximate 77% of global mango production and the Americas and Africa approximately 13% and 9% respectively (FAOSTAT, 2007). In 2005, world production of mango was estimated at 28.51 million metric tons. Between 1996 and 2005, production grew at annual rate of 2.6% (FAOSTAT, 2007).

Juice manufacturer face competition from producers who buy imported flavor concentrate and dilute them to make fruit drinks that are much cheaper. Consequently, the production and marketing of fruit juice should focus on the fact that they are made from fresh fruits with no additives. Further, the cost of equipment to form and seal cartons is too high for small scale producers and they are only sold under license. Cheaper alternativesincluding plastic pots with seeded foil lids are available as alternatives to bottles. Some processors also market juice in polythene sachets. Preservations is by pasteurization and natural activity of the juice. Some types of juice (e.g. melon juice) have low levels of acid and this can be increased by adding citric acid to give a pH below 3.5-4.0. Although some producers add preservatives such as sodium benzoate to ensure a long shelf life, this is not necessary if the juices is properly processed. Juice can be extracted from fruits in a number of ways, depending on the hardness of the raw material. Harder fruit such as pineapple are peeled and pulped using a liquidizer and pressed to extract juice. Fresh and processed pineapple is found all over the world. For every five pineapples produced, two are sold on the international market and processed pineapple product such as juice, largely dominates this markets, accounting for 80% of the total trade (Morgan et al., 2005). 

Fruit juice provides a notable amount of iron which produces healthy red blood cells to transport oxygen throughout the body. A fruit juice is always a 100% product and should not be confused with soft drinks or other refreshing drinks. Fruit juices are very important in improving the memory and concentration, reducing mental weakness and in curing the problem of heavy bleeding menstruation.

Carbohydrates are manufactured by plants and are a major source of energy in the diet comprising around half the total calories. Carbohydrates are composed of carbon, hydrogen and oxygen in a ratio of 1:2:1. Important dietary carbohydrates can be categorized as (1) monosaccharaides, (2) disaccharides and oligosaccharides, and (3) polysaccharides. Fructose (also known as laevulose and fruit sugar) is the sweetest of all monosaccharaides. Most fruits contain from 1% to 7% fructose, with some containing considerably greater concentrations. Fructose makes up about 3% of the dry weight in vegetable and about 40% of honey. As fruit ripens, enzymes cleave sucrose into glucose and fructose (invert sugar), resulting in a sweeter taste (Mahan and Escott-Stump, 2008).

Fruit juices are nutritious which offer great taste and health benefits. The 2005 Dietary Guide lines for Americans (2005) recommended consumption of several cups per day of fruits and vegetable. Most fruit juices bought from grocery stores and supermarket shelves are pasteurized. This means that the liquid has been brought to a high temperature that kills harmful bacteria. However, a small percentage of fresh fruit juices are unpasteurized. This means that there is a chance that the product may contain bacteria harmful to our health. Most people can enjoy unpasteurized juice and drinks, however, for young children, the elderly and people with weakened Immune systems, the effect can be severe or even deadly (Fasoyiro et al., 2005).

Fruit juices are well recognized for their nutritive value, mineral and vitamin content. They are beverages that are consumed for their nutritional value, thirst-quenching properties and stimulating effect or for their medicinal values (Fawole and Osho, 2002). Contamination of fruit juice by bacterial may occur when the organism enters the processing plant or on the surface of the fruit having originated from soil, untreated surface water, dust and decomposing fruit. The degree of contamination varies depending upon how the fruit was handled from the field and in the processing plant. Proper handling, washing and sanitizing the fruit contribute materially to good product quality. The low pH of fruit juices greatly limits the number and the type of bacteria that can survive or grow at this low pH but some bacterial that their pH is lower than that of the fruit juice can grow at this condition (Ryu and Beuchat, 1998). Yeast and molds are also present and can grow when the juice is held at a temperature permitting their growth. Yeasts are primarily responsible for the spoilage of chilled juice that is not sterile and some can withstand the effect of chemicals used to preserve those (Sandeep et al., 2001). Most industrial juice concentrators use high temperature evaporation (thermal accelerated short time evaporation) and microbes are generally killed during this process and the freezing process should kill many of the survivors though this process will preserve the ultimate survivor. Thus frozen concentrated fruit juice should have few if any microbes (Parish, 1997). It is possible to reduce the growth of bacterial in fruit juices by addition of some chemical preservatives, thus inhibiting abnormal flavor, odour and spoilage of fruit juices and possibly improving shelf-life and permitting preservation for longer period with maximum retention of its nutritive valve.

Unpasteurized fruit and vegetable juice have posed serious public health risk in recent years. Seventy people including a child who died-become ill in 1996 after drinking unpasteurized apple juice contaminated by a strain of Escherichia coli bacteria (Amato, 1999). In 1999 and 2000, unpasteurized orange sickened hundred people in United States and three Canadian provinces. A 2005 study in Japan found out that up to 52% of commercial fruit juices sold in Japan were contaminated with thermostable acidophilic bacteria (Furuhata et al., 2005).

Bacteria are responsible for the contamination and spoilage of packaged fruit juices resulting in discoloration, abnormal flavour and odour rendering it unacceptable for human consumption. The bacterial strain that spoil fruit juices includes, Bacillus licheniformis, Aeromonas hydrophila, Bacillus circulans, Proteus morganii, Pseudomonas chlororaphis, Bacillus alvei, Pseudomonas cepacia and so on. Their presence may pose risks to consumer’s health and should not be taken for granted (Hatcher et al., 1992).

1.2 Statement of the research problem

It is common knowledge that pH plays a vital role in ensuring successful biochemical reactions within the body. Ailments like peptic ulcers are known to be related. In low acid condition, the stomach walls are known to corrode causing severe pains. This statement is normally treated with alkaline antacid. This research was conducted to document the pH values of common ripe fresh fruit juices with a view to making available information that could be useful in providing alternatives to commercial antacid drugs by using fruits that have alkaline juices to neutralize the acidity of the stomach. 

1.3 Objectives of the study

The objective of this work is to ascertain the level of pH value of fresh fruits commonly consumed in Akwa Ibom State and compare same with their respective processed fruit juices sold in our departmental stores for human consumption.

1.4 Justification of the study

pH value varies with respect to type of fruit. Currently, consumers choose diets based on the associated nutritional and health benefits instead of taste (Katan and De Roos, 2004). Hence, the successful completion of this study will make available information regarding the pH value of the various fresh fruit juices and commercial fruit juices to help consumers to make informed decisions whether they should consume whole fruits or their processed fruit juices with respect to their pH values. Information obtained from this work will serve as an update to previous data obtained and will help in establishing a standard literature on this subject matter. Also medical care givers may find the outcome of this research useful in handling such cases as peptic ulcer which is a pH dependent ailment.

1.5 Scope of the work

This work will focus on ripe fresh and processed fruit juices sold and consumed in Uyo metropolis.



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