ABSTRACTS
The physicochemical and microbiological changes associated with wine production with pineapple using palm wine yeast was studied. Pineapple juice was extracted and its sugar content was optimized before it was inoculated with yeast isolated from fresh palm wine and fermented for 11 days while the quality attributes and microbial biomass were determined every 48hours. The characteristics includes biomass build up, alcohol production, acidity levels, total solids, sugar content and specific gravity. Results obtained show that there was increase in the microbial biomass from 0.08g/L to 2.24g/L while alcohol production increased from 2.64 to 9.58%. The physiochemical properties also changed with fermentation time in which the pH decreased from 6.10 to 2.4 while titratable acidity increased from 0.33% to 2.39%. Sugar content decreased from 21.52% to 0.64% while total solid and specific gravity decreased from 18.82% to 6.37% and from 1.186 to 1.011 respectively. The temperature fluctuated between 30.00C and 32.00C. The fermentation dynamics was faster at the early days but slowed down after the 5th day. The observed changes in the physiochemical properties with fermentation time was attributed to the effect of the microbial activity during the fermentation while the increase in biomass was such as a proof that the yeast adapted well in the fermenting Must.
TABLE OF CONTENTS
Title
Page i
Certification
ii
Dedication
iii
Acknowledgement
iv
Table
of contents v
Lists
of Tables vii
Abstract
viii
CHAPTER
ONE
1.0 Introduction 1
1.1 Aim 8
1.2 Objectives 8
CHAPTER TWO
2.0 Literature
Review 9
2.1 Pineapple
12
CHAPTER THREE
3.0 Materials
and Methods 17
3.1 Collection
of Samples 17
3.2 Sample/Media
Preparation 17
3.2.1 Preparation
of Media for Yeast Isolation. 17
3.2.2 Isolation
of Palm Wine Yeast 18
3.3 Characterization
of Yeast Isolate 18
3.4 Preparation
of Pineapple Must 18
3.4.1 Determination
of Sugar Content of Juice 19
3.4.2 Optimization
of Must 20
3.5 Preparation
of Inoculum 20
3.6 Fermentation
of Must 20
3.7 Determination
of Physicochemical Properties 21
3.7.1 Determination
of temperature 21
3.7.2 Determination
of pH 21
3.7.3. Determination
of T. T. A 21
3.7.4 Determination
of total solids 22
3.7.5 Determination
of specific gravity 22
3.7.6 Determination
of alcohol 23
3.7.7 Determination
of biomass 23
3.7.8 Sensory
Evaluation 24
3.8 Statistical
Analysis 25
CHAPTER FOUR
4.0 Results 26
CHAPTER FIVE
5.0 Discussion, Conclusion and Recommendation 37
5.1 Discussion 37
5.2 Conclusion 39
5.3 Recommendations
40
References 41
LIST OF TABLES
Table Title Page
1 Changes
in quality characteristics of fermenting
Must
during wine production 27
2 Quantitative Representation
of the Panelist Score
Of Pineapple wine 28
LIST OF FIGURE
Figure Title Page
1 Flow
chart of pineapple wine production 16
2 Changes in temperature of fermenting
pineapple juice during wine production 29
3 Changes in pH of fermenting pineapple juice during wine
production 30
4 Changes in total solid in fermenting pineapple juice during
wine production 31
5 Changes in TTA of fermenting pineapple juice during wine
production 32
6 Changes in sugar of fermenting pineapple juice during wine
production 33
7 Changes
in specific gravity of fermenting pineapple juice during wine production 34
8 Changes in biomass in fermenting pineapple juice during wine
production 35
9 Changes
in alcohol of fermenting pineapple juice during wine production 36
CHAPTER ONE
1.0
INTRODUCTION
Fermentation was described by
Prescott et al., (2008) as any process involving the mass culture of
microorganisms either aerobically or anaerobically, and also the use of an
organic substrate as the electron donor and the same partially degraded organic
substrate as an electron acceptor. According to Pelezar et al., (2000),
Louis Pasteur found out that fermentation of fruits and a grain resulting in
alcohol production was brought about by microorganisms.
Fermentation
is the metabolic conversion of a carbohydrate such as sugar into an alcohol or
an acid using yeast, bacteria or a combination thereof (mixed culture) (Adams,
2005). It is also the slow decomposition of organic substance induced by microorganisms
or by complex nitrogenous substances (Enzymes) of plant and animal origin
(Board, 2003). In this process also, starch is broken down into fermentable
sugars by fungal enzymes such as alpha amylase and glucoamylase to facilitate
fermentation by yeast, mainly Saccharomyces
species. Fermentation could occur under anaerobic or aerobic conditions and
yields lactate, acetic acid, ethanol, carbon dioxide or some other simple
product (Esechie, 2009). The numerous important products obtained by
fermentation such as antibiotics, vitamins, feed supplements, and blood plasma
expanders, has made fermentation as an industrial method for making specialty
and various industrial chemicals gain wide attention (Horold et al.,
2008). The production of industrial chemicals enhances the economic growth of
any nation. Ethanol is one such industrial chemical used diversely as a solvent
for chemicals, as an intermediate in the production of liquid detergents, in
the manufacture of drugs, plastics, polishes, plasticizers and cosmetics, as
antifreeze and as fuel ethanol (Akpan et al., 2005). Ethanol can be
produced by Ethylene hydration or Fermentation (Agu et al., 2006).Ethanol
can be made by fermentation using a number of renewable feed stocks, including
sugar crops such as sugarcane, starch containing grains such as corn, or lignocelluloses
materials including agricultural residues, herbaceous crops, and wood (Wang et
al., 2004). Palm wine has been used locally in Nigeria for ethanol
production by rural farmers. Palm wine is an alcoholic beverage obtained from
the sap of various species of palm trees and is common in various parts of
Africa. In Nigeria, it is abundant in the Niger delta and Rivers state in
particular. The sap is extracted and collected by a tapper. Typically the sap
is collected from the cut flower of the palm tree. A container is fastened to
the flower stump to collect the sap. The white liquid that initially collects
tends to be very sweet and non-alcoholic before it is fermented (Okafor, 2003).
Palm wine is a whitish, effervescent
alcoholic beverage produced by the spontaneous fermentation of the sap of tree
pals (family: Palmae). It is consumed in tropical and sub-tropical countries
where palm grows.
These include South America, Asia and
Africa (Blange and Bissir, 2009). It is refer to as toddy in Asian countries
and tuba in South America. The type of palm which the fermented sap is consumed varies in
different parts of the world according to the type of palm wine obtained from
oil palm (Elaeis guineensis), and raphia palm (Raphia vinifera)
and Palmyra palm (Borassus flaellifer). Palm wine is a general name for
alcoholic beverages produced from the sap of palm trees. It is different from
the grape wines in that it is opaque. It is consumed all over the tropical
world in Africa, Asia and South America. Palm wine is usually whitish and
effervescent liquid both properties were derive from the fact that organisms
are numerous and alive when the beverage is consumed (Okafor, 2004).
Palm wine differs from conventional
beers and table wines produced in the modern brewery and winery in three ways.
First, the media fermented for such beers are usually grains and for the wines,
grapes and fruit juice are used in wine. The basic principle is however, is the
same: a sugar solution is fermented, essentially by yeast (Saccharomyces species). Secondly, whereas there is
control of fermentation during the production of modern beers and
wine. Fermentation of palm wine is not controlled. Thirdly, the European beer
and wines are usually clarified by removing microbial cells and other suspended
material. Palm wine on the other hand is consumed without such clarifications.
In essence, the basic differences between the true wines and the palm wine are
a matter of technological differences between wine-making techniques and palm
wine production methods. The methods of producing palm wine are likely to
continue to change with enhanced technological advancement of the consuming
countries (Benjakul, et al.,
2009).
During fermentation the yeast Saccharomyces
cerevisiae produces a broad range of aroma-active substances, which are
vital for the complex flavor of fermented beverages such as beer, wine and sake
(Fleet et al., 2007). Flavour active
substance produced by fermenting yeast cells can be divided into six groups,
sulfur containing molecules, phenolic compounds and volatile esters (Saerens et al., 2010). Although volatile esters
are only trace compounds in fermented beverages, they comprise the most
important set of derived aroma active compounds. Volatile esters are of major
industrial interest because they are responsible for the highly desired fruity,
candy and perfume like aroma character of beer, wine, and sake (Fleet et al., 2007). Flavour in the most important
distinguishing characteristics of most fermented foods, flavour is usually
classified according to the source of different compound contributing to it.
This include flavour contributed by the substrate prefermentative flavour
(compound formed during extraction and conditioning of substrate), fermentative
flavour (produced by yeast and bacteria during alcoholic and malolactic
fermentation) and past, fermentative flavour (compound that appear during the
storage period) (Orlica et al.,2007).
Post fermentative flavour is usually a result of enzymatic. Is a complex
phenomenon involving a number of factors in particular, it depends on the
nature and concentration of the compounds initially present in the substrate,
the capacity of the yeast to transform them and the fermentation condition employed.
Yeasts are eukaryotic microorganisms
classified as fungi, with over 1,000 species currently known and described. It
is believed that the species described so far represent only about 1% of all
1.5 million yeast species believed to exist on earth (Hutkins, 2006). Yeasts
are unicellular fungus that reproduces either asexually by budding and
transverse division (binary fission) or sexually through spore formation
(Prescott, 2002). Although most yeast are unicellular, some species with yeast
forms may become multi cellular through the formation of a string of connected
budding cells known as pseudohyphae, or false hyphae, as seen in moulds. Yeast
size can vary greatly depending on the species, typically measuring 3-4μm in
diameter, although some yeast can reach over 40μm. The yeast species Saccharomyces
cerevisae has been used in baking and fermenting alcoholic beverages for
thousand years (Legrass et al., 2007).
Pineapple (Ananas satirus) is
produced in large quantity in Nigeria. Madrid and Felice (2005) reported that
about 4000 to 6000 tons of pineapple fruits are produced annually, most of them
are wasted due to poor handling and poor storage methods. Fermenting pineapple
juice goes a long way in reducing wastages and increasing local farmer’s
income. The nutritional values of pineapple fruits according to Ihekoronye and
Ngoddy (2007) are 54 mg/100 mL of vitamin C, 12% (w/v) of total sugars, 0.3% of
protein, 0.1% of fats, 12 mg of calcium, 0.3 mg of iron, 0.08% of thiamine and
0.1 mg of niacin.
Yeast species are very useful in many
industrial processes such as the production of alcoholic beverages, biomass and
various other metabolic processes (Frazier and Westhoff, 2008). In baking and
alcohol production, palm wine yeast (Saccharomyces cerevisiae) is most
commonly used to convert sugars into ethanol and as the yeast utilizes the
sugar, carbon dioxide and alcohol are produced (Zhou, 2002).
Wine production is a product of old
biotechnology (Alian and Musenge, 2006), although the modern methods of
production are in carefully controlling the processes in bioreactors. The juice
from the crushed fruit is usually fermented by pure cultures of certain strains
of yeast (Maldonado et al., 2005).
Processing steps includes crushing
according to Querol et al. (2003).
The ability to produce palatable
effervescent beverage by alcoholic fermentation of natural fruit juices is a
demonstration of inherent ingenuity of man. The nutritional role of wine is
important since its average contribution to total energy intake is estimated to
be 10 to 20% in adult males (Macrae et al.,
2011).
During the past few decades, grapes
are the main fruits that were used for wine production. Despite that, several
studies have investigated the suitability of other fruits as substrates for the
purpose of wine production (Joshi and Bhutani, 2005; Joshi et al., 2003; Ndip et al.,
2001; Okunowo et al., 2005).
Moreover, the non-availability of
grapes, which is usually the fruit of choice for wine production in the tropics
has necessitated the search for alternative fruit source in Nigeria and other tropical
countries (Alobo and Offonry, 2009). In, Nigeria, there is abundance of
tropical fruit which includes passion fruit, watermelon, pineapple, plum,
orange etc., these fruits are highly perishable, and susceptible to bacterial
and fungal contamination as a result they fail to reach the market due to
spoilage, mechanical damage and over ripeness (Ihekoroye and Ngoddy, 2007).
Besides, these fruits are difficult to keep for considerable length of time;
hence the ripe fruits are utilized either as fresh or processed into juice and
specialty products (Oyeleke and Olaniyan, 2007).
High rate wastage of these fruits
especially at their peak of production during their season necessitates the
need for alternative preservation food forms towards an enhanced utilization of
these fruits. The production of wines from common fruits could help reduce the
level of post harvest losses and
increase variety of wines (Okoro, 2007; Alobo and Offonry, 2009). Although,
many genera and species of yeasts are found in musts, Saccharomyces cerevisae
is the main yeast strain that is commonly reported to be responsible for
alcoholic fermentation (Pretorius, 2000; Querol et al., 2003). However, many studies have investigated the use of
other yeast strains (Ciani and Maccarelli, 2007; Okunowo et al., 2005) and also combination of yeast strains
(Clemente-Jimenez et al., 2005) in
fermentation especially in wine production. Reports have shown that the
fermentation of fruit juices using yeast from different sources creates variety
in flavour and varying levels of alcoholic contents in wines Clemente-Jimenez et al., (2005) in their work reported Pichia
fermentans as good starter strains for most fermentation as Pichia fermentans
in mixture with S. cerevisae improve the aroma as well as the characteristics
features of the wine.
The fermentation of wine is known to
be a complex process with various ecological and biochemical processes
involving yeast strain (Fleet, 2003). Palm wine is a naturally sweet fermented
beverage obtained from the sap of Elaeis species and the sap of Raphiaspp,
which contains a heavy suspension of live yeasts and bacteria (Okafor, 2000).
It is mostly common in Africa, especially Nigeria. Most studies on palm wine
have reported its potentials as source of yeast isolate for the fermentation industries.
Okafor (2004) in his study isolated seventeen yeast strains, four belonging to
the species of Candida, twelve to the genus of Saccharomyces and
one to Endomycopsis species. In grapes, yeast strains, such as Hanseniasporauvarum,
Kloeckeraapiculata, Candida,Pichia, Rhodotorula and Kluyveromycesare known
to be predominant (Duart et al.,
2010).
The fermentation for the elaboration
of beverage is known to depend on the performance of yeast to convert the
sugars into alcohol and esters. Besides, the different species of yeast that
develop during fermentation determine the characteristic of the flavour and
aroma of the final product. Also, because different fruits have different
composition, there is the need for yeast strains to adapt to different
environments, such as sugar composition and concentration of acetic acid
(Fleet, 2003; Duart et al., 2010).
Although, tropical fruits and several yeast strains have been screened for
their suitability in wine production, most studies have either focused only on
the suitability of the fruits or the yeast strains.
1.1
AIM
The aim of this work was to produce wine
with pineapple juice using yeast from palm wine.
1.2
OBJECTIVES
The objective includes specifically the
following;
1. To
isolate and identify yeast from palm wine.
2. To determine the changes associated with
pineapple juice fermentation to produce wine.
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