MICROBIAL QUALITY AND FLAVOUR PROFILES OF WINES PRODUCED FROM SELECTED THREE TROPICAL FRUITS OF NIGERIA

ABSTRACT

Wine may be defined in general as a product of the alcoholic fermentation of any fruit by yeast. Fresh orange fruit, pineapple and water melon were purchased from Abak main market, Akwa Ibom state, Nigeria. Peeled pieces of orange, pineapple and water melon were measured respectively and was recorded (1707.4g). The 1707.4g of each of the peeled fruits were crushed and pressed to released pulp.2000ml of water was added. 40.5g of sugar (sucrose) was added for amelioration and mixed well and blended to obtain juices. Six different wines from orange fruit, Pineapple and water melon were produced using two strains of wine yeasts; (Saccharomyces ellipsiodeus and saccharomyces bayanus. The Juices were pasteurized for 1610F for 15 seconds to reduced microbial activities. The juices were then cooled for 390F and pitched with a starter of both strains of the yeasts. During the process of fermentation, physicochemical changes such as pH, TSS, S.G & %sugar of orange fruit juice was observed to decrease from 5.98 to 4.20, 17, 954 to 10.753, 1.025 to 0.9795 respectively from day 1 to day 12. while %alcohol, T.T.A were increased from 1.50 to 12.00 and 0.000 to 16.13 from day 1 to day 12 in both strain of yeasts. Same trends were observed from pineapple and water melon juices. Wine from either orange fruit juice or pineapple juice in both strain of yeast were found to be acceptable because of its high alcoholic concentration of 16.13, 16.00, 17.10% and 16.30% at the end of fermentation in both yeast strains. But wine produced from water melon in both strains of yeast was unacceptable because of their low alcoholic concentration of 7.2% and 7.0% respectively. However, wines produced using water melon “must” was found to contain high load of lactic acid bacteria as contaminants. These organisms are responsible for producing lactic acid in the wine and bringing the pH value of the wine very low, increasing the wine acidity, astringency and sourness. Similarly, wines produced from pineapple and orange juices was acceptable as its were Scored high (6-9) by panelist compared to wine produced from water melon as they were scored low (3-6) by both yeast strains, hence it was unacceptable. Similarly, ester flavour of 77.31µg/kg and 32.15µg/kg ethylhexanoate in pineapple and orange wines in both strains of yeast accounted for the sweet taste of the wines, whereas ethylhexanoate flavour of 22.2µg/kg and 20.8µg/kg in water melon accounted for low sweet flavour in water melon wines.

TABLE OF CONTENTS

CONTENTS                                                                                                              PAGES

Cover Page                                                                                                                              i

Title Page                                                                                                                                ii

Declaration                                                                                                                              iii

Dedication                                                                                                                              iv

Certification                                                                                                                            v

Acknowledgement                                                                                                                  vi

Table of Contents                                                                                                                   vii

List of Tables                                                                                                                          xi

List of Figures                                                                                                                         xii

Abstract                                                                                                                                  xiii

CHAPTER 1                                     INTRODUCTION

1.1       Background of Study                                                                                                 1

1.2       Statement of Problem                                                                                                 4

1.3       Justification of the Study                                                                                           4

1.4       Objectives of the Study                                                                                              4

CHAPTER 2             -                       LITERATURE REVIEW                          

2.1       Orange Fruit                                                                                                                5

2.1.1    Origin and Distribution                                                                                               5

2.1.2    Nutrient Composition and Food Value                                                                      5         

2.2       Pineapple                                                                                                                     5

2.2.1    Origin and Distribution                                                                                               5

2.2.2    Nutrient Composition and Food Values                                                                     6

2.3       Water Melon                                                                                                               6

2.3.1    Origin and Distribution                                                                                              6

2.3.2    Nutrient Composition and Food Values                                                                    6

2.4       Wine                                                                                                                            7

2.5       Wine Making Procedure                                                                                             9

2.6       Importance of Soaking and Skin Contact in Wine Making                                        11

2.7       Importance of Wine Yeast Characteristics for Wine Making                                     11

2.8       Biochemical Changes during Wine Making                                                               13

2.8.1    Primary/alcohol Fermentation                                                                                     14

2.8.2    Secondary Fermentation                                                                                             14

2.8.3    Chemistry of Fermentation during Wine Making                                                       15

2.8.4    Embden, Meyerhoff and Panas Path of Glycolysis                                                    15

2.8.5    Aging the Wine                                                                                                           17

2.8.6    Factors Influencing Fermentation of “Must”                                                             19

CHAPTER 3                                     MATERIALS AND METHOD

3.1       Materials                                                                                                                     22

3.2       Method                                                                                                                        22

3.2.1    Preparation of “Must”                                                                                                 22

3.2.2    Activation of Starter Culture (Yeast)                                                                         22

3.2.3    Certification of Starter Culture Viability                                                                    23

3.2.4    Pitching                                                                                                                       23

3.2.5    Production of Wine                                                                                                    25

3.2.6    Physicochemical Analyst                                                                                            26

3.2.6.1 Determination of Specific Gravity                                                                             26

3.2.6.2 Determination of Alcoholic Content                                                                          26

3.2.6.3 Determination of pH                                                                                                   26

3.2.6.4 Determination of Titratable Acidity                                                                           27

3.2.6.5 Determination of Sugar Concentration                                                                       27

3.2.6.6 Statistical Analysis                                                                                                      27       

3.2.6.7 Biochemical Identification Technique                                                                        28

CHAPTER 4                         RESULT AND DISCUSSION                                            32

4.1       Physicochemical Changes during fermentation of juice from Orange to Wine

            using Wine yeast (Saccharomyces ellipsiodeus)                                                         32                                                                                           

4.2       Physicochemical Changes during fermentation of Juice from Orange to Wine

            Using  Baker yeast (Saccharomyces bayanus)                                                            36

4.3       Physicochemical Changes during fermentation of Juice from Pineapple to Wine

using wines yeast (Saccharomyces ellipsiodeus)                                                        38

4.4       Physicochemical Changes during fermentation of Juice from Pineapple to Wine

using  bakers yeast (Saccharomyces bayanus)                                                            40

4.5       Physicochemical Changes during fermentation of Juice from Water melon to Wine

using Wins yeast (Saccharomyces ellipsiodeus)                                                          42

4.6       Physicochemical Changes during fermentation of Juice from water melon to Wine

using bakers yeast (Saccharomyces bayanus)                                                             44

4.7       Microbial Identification Result                                                                                   45

4.8       Sensory Characteristics of the Wine Samples                                                 79

CHAPTER 5             CONCLUSION AND RECOMMENDATIONS

5.1       Conclusion                                                                                                                  81

5.2       Recommendation                                                                                                        82

References                                                                                                                  83

LIST OF TABLES

Table 4.1         Physicochemical Changes during fermentation of juice from Orange to       33

Wine using Wines yeast)

Table 4.2         Physicochemical Changes during fermentation of juice from Orange to       36

                        Wine using bakers yeast)

Table 4.3         Physicochemical Changes during fermentation of juice from Pineapple        38

To Wine using Wines Yeast)

Table 4.4         Physicochemical Changes during fermentation of juice from pineapple        40       

 to Wine using Bakers Yeast)

Table 4.5         Physicochemical Changes during fermentation of juice from Water

melon to Wine using wines yeast)                                                                  42

Table 4.6         Physicochemical Changes during fermentation of juice from Water

 melon to Wine using bakers yeast)                                                                44

Table 4.7a        Microbial isolate in water melon wine by wines yeast                                    47

Table 4.7b       Microbial isolate in water melon wine by bakers yeast                                   48

Table 4.7c        Microbial isolate in Pineapple wine by bakers yeast                                       49

Table 4.7d       Microbial isolate in Pineapple wine by wines yeast                                        50

Table 4.7e        Microbial isolate in Orange wine by bakers yeast                                           51

Table 4.7f        Microbial isolate in Orange wine by Wines yeast                                           52

Table 4.8         Summary of volatile Descriptors produced from various wines                     74

LIST OF FIGURES

Figure 1           Flow Chart of Processing Pineapple, Water melon and Orange Fruit            8

Figure 2           Diagram Illustrating Industrial Production of Wine                                       9

Figure 3           Structure of Glycolysis                                                                                   18

Figure 4           Principles of Food flavour Chart.                                                                   53

Figure 5           Concentration (µg/kg) of ester compounds in pineapple

wine fermented with Wines yeast strain                                                         53

Figure 6           Concentration (µg/kg) of ester compounds in pineapple wine fermented

with bakers yeast strain                                                                                   55

Figure 7           Concentration (µg/kg) of ester compounds in pineapple wine

fermented with Wines and bakers yeast strains                                              56

Figure 8           Concentration (µg/kg) of terpenes in pineapple wine produced with

Wines yeast strain                                                                                           57

Figure 9           Concentration (µg/kg) of terpenes in pineapple wine fermented

with bakers yeast strain                                                                                   58

Figure 10         Concentration (µg/kg) of terpenes in pineapple wine produced with

Wines and bakers yeast strains                                                                       59

Figure 11         Concentration (µg/kg) of lactones, ketones and aldehydes in

pineapple wine fermented with Wines yeast strain                                        60

Figure 12         Concentration (µg/kg) of lactones, ketones and aldehydes in pineapple

wine fermented with bakers yeast strain                                                        61

Figure 13         Concentration (µg/kg) of lactones, ketones and aldehydes in pineapple

wine fermented with Wines and bakers yeast strains                                     62

Figure 14:        Concentration (µg/kg) of volatile compounds orange wine fermented

with Wines yeast                                                                                             64

Figure 15         Concentrations (µg/kg) of volatile compounds in orange wine fermented

with bakers yeast                                                                                            66

Figure 16         Concentrations (µg/kg) of volatile compounds in orange wine fermented

with Wines and bakers yeast strains                                                               68

Figure 17         Concentration (µg/kg) of alcohol compounds in watermelon wine

fermented with Wines yeast                                                                           69

Figure 18         Concentration (µg/kg) of alcohol compounds in watermelon wine

fermented with bakers yeast                                                                           67

Figure 19         Concentration (µg/kg) of alcohol compounds in watermelon wine

fermented with Wines and bakers yeast strains                                              70

Figure 20         Concentration (µg/kg) of ester compounds in watermelon wine

fermented with Wines yeast strain                                                                 71

Figure 21         Concentration (µg/kg) of ester compounds in watermelon wine

fermented with bakers yeast strain                                                                 72

Figure 22         Concentration (µg/kg) of ester compounds in watermelon wine

fermented with Wines and bakers yeast strains                                              73

Figure 23         Strength of taste descriptor of watermelon wine fermented

with Wines yeast                                                                                             75

Figure 24         Strength of taste descriptor of watermelon wine fermented

with bakers yeast                                                                                            75

Figure 25         Strength of taste descriptor of pineapple wine fermented

with Wines yeast                                                                                             76

Figure 26         Strength of taste descriptor of pineapple wine fermented

with bakers yeast                                                                                            76

Figure 27         Strength of taste descriptor of orange wine fermented with

Wines yeast                                                                                                     77

Figure 28         Strength of taste descriptor of orange wine fermented with bakers yeast     77

CHAPTER ONE

INTRODUCTION

           1.1             BACKGROUND OF THE STUDY

Wine is any alcoholic beverage produced from juices of variety of fruits by fermentative action of microorganisms either spontaneously or seeding with a particular strain mainly of yeast species to adopt a particular quality of wine. Ideally, distinctive flavours of wine originate from raw materials during alcoholic and malolactic fermentation (Cole and Noble, 2020). All over the world, different raw materials are used for the production of alcoholic beverages according to location and ingredients (Allan, 2019) and (Block and Glen, 2000).

Microorganisms are fundamental to wine making industries. In addition to microbial succession, another index of interest is the quality attribute (Jay, 2018) and (WardBaj,2021) isolated the following microorganism from ripened plantain fermented alcoholic beverage: SaccharomycesCerevisiae, SaccharomycesChevaleri, BaillusSubtilis, Lactobacillus Mesenteroids, Streptococcus Lactus and Micrococcus sp.

There has been some controversy over the relative merits of spontaneous with natural flora of the ‘must’ and fermentation carried out with selected yeast strains. While Benda (2017) found that spontaneous fermentation produced a better rounded and more complex aromatic quality Smhitte e tal (2018) found it a significant preference for wine produced with selected yeast.

Seeding of the fermentation is undertaken with the assumption and expectation that the inoculated strain will out-compete and dominate over indigenous strains of Saccharonmycesyeasts. Although there is high probability that inoculated S. Cerevisiae will dominate the fermentation, seeding will not necessarily guarantee the dominance of any particular strain or its exclusive contribution in the fermentation Altari (2015).

Different types of wine have their own special character, however, because grapes and local fruits grown in different regions differ slightly in composition particularly with respect to their volatile components which contribute to flavour and bouquet – and because different regions have evolved their own techniques of wine making (Nelson, 2000). Although the art of wine-making is an ancient one, modern methods of production are carefully controlled, being the outcome of much research. The essential stages in wine-making are pressing, fermentation, clarification and bottling.

During fermentation which follows, glucose and fructose present in the juices are converted into alcohol. If fermentation continues until all the sugars are used up the resulting wine will be dry, while if it is stopped while some sugar remains it will be sweet (Bajaj e tal., 2018). In any case yeasts cannot tolerate an alcohol content greater than 16%, so that natural wines cannot contain more alcohol than this, and in general they contain about 10%.

There are a bewildering and fascinating array of different wines, each being named by reference to its place of origin. These wines differ mainly according to whether they are red or white, natural or fortified.

Microscopic examination of young cultures of bakers or Wines yeast grown in liquid media reveals that the culture is a mixture of translucent, vegetative cells Ezeama (2017). They are made of single cells, including mother cells with buds and developing daughter cells, which attach to it predominantly. However, pairs, short chains and clusters of cells occur frequently. Cell size of active cultures of bakers or Wines yeast varies from 4 - 8µm in width and 5 – 15µm in length (Ezaema, 2017). Cell may be round, ovoid, ellipsoidal or filamentous. In culture there is a considerable variation in the size and shape of an individual cell, depending on age and environment. Some strains of Wines yeast form long, cylindrical buds and cells in continuous fermentation systems.

Yeast cell morphology can be determined by the staining technique ordinarily used for bacteria. (Ezaema, 2017). The use of weak aniline dye is useful.

Culture preparation involves the use of mother culture, which is prepared daily from previous mother culture, which is originally from the stock culture.

These mother cultures can be used to inoculate a large quantity of culture medium to produce the mass or bulk culture to be used in the fermentation process. Often however, the fermentation is on such a large scale the several intermediate cultures of increasing size must be built up between mother culture and the final bulk or mass culture (Bhajophale e tal.,2018).

1.2       Statement of the Problem 

Over many centuries, grapes had played dominant roles in wines production. In Nigeria, Grape is scarce as it is not tropical fruits that have abundance fermentable sugar. Most of these fruits are not industrially being used especially in wine production. These indigenous fruits need to be tapped for wine making to add value to them and at the same time make wine available at affordable price for the average Nigerians. This would also reduce unemployment and may lead to exportation for revenue generation to Nigeria.

1.3 Justification of the Study

4        The fruits are abundant in the entire Southern and Eastern part of Nigeria.

5        They are cheap.

6        The process of production is not stressful and cumbersome.

7        It can provide small scale industries for many interested entrepreneur.

1.4  Objectives of the Study

The main objective of this study was to evaluate the quality attributes of wines produced from selected fruits; including-Orange fruit, water melon and pine apple

The specific objectives are: -

i.          To produce wines from juices of Orange, pineapple and watermelon.

ii.         To determine physicochemical properties of juices during fermentation

iii.       To determine the microbial quality of the wines produced

iv.        To determine flavour profiles of wines

v.         To determine sensory evaluation of the wine

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