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.
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1.1
Research Terminologies
Beverages
Beveragesareliquidsspecifically prepared forhumanconsumption, 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
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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.
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1.2
Fruit Juice
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.
1.2.1
Fresh Juice
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).
1.2.2
Reconstituted Juices
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).
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1.2.3
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.