ABSTRACT

The sugar and mineral levels of industrially processed fruit juices (mainly 100% and 50% fruit juices) sold to consumers in Enugu state, Nigeria were determined and compared with that of freshly prepared fruit juices. The liquid nature as well as the versatility of juice has increased the ease with which fruit juices can be altered with sugar, contaminants, water or inferior juices by unethical suppliers. This research was performed to address the potential concern that industrially processed fruit juices (especially those with ‘100% natural’ and ‘no sugar added’ label) may differ in quality with respect to sugar and mineral contents (including heavy metal contents which is deleterious to quality) from extracted juice of fresh fruit, as well as to address in part the ongoing public health concerns of excessive sugar consumption, micronutrient malnutrition and heavy metal contamination. The fruit juices tested included apple, orange, pineapple and red grape juices. All industrially processed fruit juices and fresh fruits used were purchased in Enugu state, Nigeria. The fresh fruits were juiced and all samples including industrially processed and the freshly prepared fruit juices were tested for total soluble solid (TSS) content, fructose, glucose, sucrose, Na, K, Mg, Ca, P, Fe and heavy metals contents such as Cu, Zn, As and Pb. Findings from the analysis of the TSS content of fruit juice samples demonstrated no significant (p > 0.05) difference between the industrially processed and freshly prepared fruit juices; however, difference in sugar and mineral levels between industrially processed and freshly extracted fruit juices was significant (p < 0.05). Industrially processed fruit juices contained higher glucose, sucrose, Na, Ca, P, Cu and Zn contents, and lower fructose, K and Mg contents when compared to freshly prepared fruit juices. There was no significant (p > 0.05) difference in iron (Fe) and arsenic (As) contents of industrially processed fruit juices when compared with the freshly extracted juices. Lead (Pb) was not detected in any of the samples. This study demonstrated no quality issues of concern in relation to the products because all the parameters considered in the study were within the standard acceptable range for fruit juices and nectar.

CHAPTER ONE

INTRODUCTION

Fruit juices are becoming important part of modern diet in many communities. Their consumption is popular in Nigeria because of their health and invigorating benefits (Alaka et al., 2003; Ndife et al., 2013). They act as nutritious beverages and play significant roles in healthy diets because they offer good taste and varieties of nutrients found naturally in fruits (O’Neil and Nicklas, 2008; Hossain et al., 2012). In Nigeria, different kinds of seasonal fruits are available including apple, orange, pineapple, and grape which provide an abundance of vitamins, minerals, antioxidants and fibers, all of which are essential for human health (Jasmine, 2012). Fruit juice intake is a convenient way by which people receive the benefits of various fruits when whole fruit is not readily available or desired (Nitu et al., 2010). 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. Fruit juices are always 100% fruit products and should not be confused with soft drinks or other refreshing drinks (Landon, 2007). They are available either in their freshly prepared form or industrially processed form. In either case, it is expected to be free from contaminants and contain most substances which are found in the original ripe and sound fruit from which the juice is extracted, without added sugar or preservative (Hassan et al., 2014). It should be void of environmental pollutants such as toxic metals which impacts negatively on quality and are deleterious to health. Fruit juices contain water and varying concentrations of carbohydrates such as sucrose, fructose, glucose and sorbitol (Oranusi et al., 2012). They are also rich in phytochemicals, minerals and vitamins which are responsible for the several health benefits associated with their consumption, including reduction in the risk of a variety of chronic diseases such as cardiovascular disease and cancer (Cashwell, 2009). However, the beneficial health effects of fruit juices depends on the amount consumed in a daily diet, type of fruit and the content of biologically active compounds. In recent times, the quality of fruit juices is diminished with increasing concentration of toxic compounds including added sugar, heavy metals and other contaminants. Excessive sugar consumption from fruit juice has been associated with the development of obesity, type II diabetes and dental caries (Cashwell, 2009). The minerals contained in fruit juices including sodium, potassium, magnesium, phosphorus, calcium and iron are essential for good health if present in adequate concentrations (Ofori et al., 2013) and harmful when in excess or deficient, hence the need for their proper representation

Beverages

Beverages are liquids specifically prepared for human consumption, usually excluding water. This may include tea, coffee, liquor, beer, milk, juice or soft drinks. Despite the fact that most beverages including juice, soft drinks and carbonated drinks have some form of water in them, water itself is often not classified as a beverage. Beverages can be categorised as alcoholic and non alcoholic based on the percentage ethanol present. Non alcoholic beverages can further be classified into sweetened beverages and fruit/vegetable juices. A sweetened beverage is any beverage to which a caloric sweetener has been added, including carbonated or non-carbonated soft drinks, fruit punch, fruit drinks, lemonade, sweetened powder drinks, or any other artificially sweetened beverages. Fruit juices on the other hand are not sweetened drinks and should not be categorized as such. They are composed exclusively of an aqueous liquid or liquids extracted from one or more fruits with no added caloric sweeteners (Landon, 2007).

Fruit juice

A fruit juice is defined as the clear or uniformly cloudy unfermented liquid recovered from sound fruits by pressing and other mechanical means (Nnam and Njoku, 2005). It is a drink consisting of 100% pure fruit juice, which typically contains no preservatives or other added ingredients. It is a fruit product, which could be easily consumed by infants, children and adults to meet their nutrient needs particularly that of micronutrients (Nzeagwu and Onimawo, 2010).

Freshly squeezed Juice

Freshly squeezed juices are produced by squeezing the juice from the fruit of choice, which is then immediately consumed or packaged and transported to the retailer as the case may be, usually within 24 hours. These juices often do not undergo any form of pasteurization and therefore typically have a very short shelf life usually 2-3 days (Cashwell, 2009).

Concentrate

This is obtained by the removal of water from fruit juice for the purpose of achieving reduction in weight and volume for easier transportation. At the time of usage, water is added back to the concentrate to reconstitute 100% fruit juice. Juices made from concentrates are available and similar in nutrient to the freshly squeezed juice. During production, fruit juices from concentrate

are typically heat-treated, to ensure that any unwanted spoilage pathogens, including bacteria or moulds, are destroyed (Cashwell, 2009).

Fruit drinks (Juice drinks)

Fruit drinks are products which contain anything less than 100% pure fruit juice (Landon, 2007; Cashwell, 2009). The level of fruit juice contained in these drinks can be found in the ingredients panel, usually on the back of the pack. There are a vast range of products with differing percentages of fruit juice. These drinks may include those that are purchased in a ready-to-drink format, or those that require dilution prior to consumption which may include products made with sugar, as well as low sugar options made with sweeteners.

Nectars

Fruit juice nectars are defined as the fermentable but unfermented product obtained by the addition of water and sugar to fruit juice or concentrated fruit juice. It consists of less than 100%, but more than 20% fruit juice (Cashwell, 2009). The term nectar is one that is used for a diluted juice to denote a beverage that contains fruit juice and water, and which may contain sweeteners.

Smoothies

Fruit smoothies are typically combinations of homogenized/crushed fruit and juice (Landon, 2007). Most single servings of commercially available fruit smoothies (typically 250 ml) contain at least one 80 g portion of whole fruit, as well as one portion of fruit juice (150 ml).

‘Intrinsic’ and ‘Added’ Sugars

Naturally occurring (intrinsic) sugars refers to sugars that are an integral part of whole fruit, vegetable, and milk products (Johnson et al., 2009) while added sugars are defined as sugars (mainly monosaccharides and disaccharides) and syrups added to foods and beverages by manufacturer, cook or consumer during processing or preparation, including sugars and syrups added at the table. They are also referred to as free sugars (Johnson et al., 2009).

Total Soluble Solids (TSS)

They are defined as the sum of the solids which are dissolved within a substance and it is usually expressed in degree Brix (Maireva et al., 2013). Degree brix is the mass of soluble solids (mainly sugars) contained in 100 g of solution. Sugar and fruit acids are the main contributors to the total soluble solid contents of fruit juices; however, pectins, glycosidic materials and the salts of metals when present also register a small but insignificant influence on the TSS content.

Fruit juice is an unfermented but fermentable liquid or juice intended for direct consumption, obtained from the edible portion of sound, appropriately mature and fresh fruit by mechanical extraction process and preserved exclusively by chemical and physical means (Oranusi et al., 2012). Fruit juice is a fruit product, which could be easily consumed by infants, children and adults to meet their nutrient needs, particularly that of micronutrients (Nnam and Njoku, 2005; Nzeagwu and Onimawo, 2010). It can be freshly squeezed or made from concentrate.

Freshly squeezed juices are produced by ‘squeezing’ the juice from the fruit of choice, which is then packaged and transported to the retailer usually within 24 hrs. These juices often do not undergo any form of pasteurization and therefore typically have a very short shelf life usually 2-3 days. However, they may undergo high-pressure treatment and/or modified-atmosphere packaging to increase their shelf life. The term “F resh Juice” in most cases applies to those juices prepared in front of the consumer. If the juice is pasteurized, or contains juice concentrates or “stored” juices, then it is not fresh juice (Cashwe ll, 2009).

A reconstituted fruit juice is the product obtained by replacing the water extracted from the juice during concentration, and by restoring the flavours. They are commonly referred to as juice ‘from concentrate’. They are common to commercial j uices where there is need to increase shelf life as well as the ease of transportaion. The juice is extracted from the fruit the same way as done for fresh juices after which the extracted fruit juice is concentrated by evaporating the water naturally present in it. This concentrate is properly preserved often by freezing before being transported to its destination, where water is added back to reconstitute the juice to 100% fruit juice or alternatively, the concentrate can be used as an ingredient in a cordial drink. After reconstitution, fruit juices from concentrate are typically pasteurized, to ensure that any unwanted spoilage pathogens, including bacteria or moulds, are destroyed. The shelf life of the product is determined by the temperature of pasteurization. Long-life products are those products pasteurized at a temperature of approximately 90°C for a short time usually10-20 seconds. They have a shelf life of approximately 6-9 months. Short-life products are pasteurized at a lower temperature (70-75°C) for 10-20 seconds and product s typically have a shelf life of 2-6 weeks (Cashwell, 2009)

• Common Fruits and Fruit Juices

Fruits have been a part of human diet over the years. They are also considered as food supplements and are recommended internationally as essential to healthy nutrition, because they contain high quantity and quality of water, sugars, vitamins and minerals (Ndife et al., 2013). Fruit consumption has been reported to contribute to the prevention of degenerative processes, particularly lowering the incidence and mortality rate of cancer and cardio-cerebrovascular diseases (Krejpcio et al., 2005). They contain phytochemicals which act against oxidative reactions in the human body (Vanamala et al., 2006; Okwu and Emenike, 2006). Fruits and vegetables are very perishable in nature; therefore high post harvest losses resulting from lack of cold storage facilities on the farms, improper handling and inadequate processing facilities occur immediately after harvest, during distribution and marketing (Alaka et al., 2003; Landon, 2007; Adubofuor et al., 2010; Ndife et al., 2013), hence the need to process them into fruit juices.

1.2.3.1 Apple Juice

Apple (Malus domestica) features oval or pear shaped (Figure 1). Its outer peel comes in different hues and colours depending upon the cultivar type. Internally, its crispy, juicy pulp is off-white to cream in colour, and has a mix of mild sweet and tart flavour.