Storage Stability, Microbiological And Physicochemical Quality Of Zobo (Hibiscus Sabdariffa) Drinks Blended With Leaf Extracts

ABSTRACT

This work present information on the storage stability of zobo drink blended with leaf extracts with local names; “Nchanwu” (Ocimum gratissimum), “Uziza” (P. guineense) and “Moringa” (Moringa oleifera). This study aimed at improving microbial quality of zobo drink thereby increasing its shelf life using natural spices. Zobo drink was prepared using hot water extraction method and the juice obtained was blended separately with aqueous extracts of M.oleifera, O.gratissimum and P. guineense leaves. Microbiological and physicochemical properties of the various blends of zobo were investigated at day 0, day 1, day 3, day 5 and day 7 during the one week duration of the study. The results obtained from this study showed that zobo samples contained different concentrations of ascorbic acid which ranged from 8.21 mg/100g to 28.75 mg/100g. The pH range was between 2.3 to 6.1 while the titratable acidity was between 0.25% to 0.89%. The bacterial counts of the different samples during storage showed that there was an increase in bacterial growth from day 0 up to day 5 but decreases at the 7th day of storage. In the control samples (Unblended zobo) values obtained throughout the period of storage ranged from 24.7 x 104 to 42.0 x 103 cfu/ml. M25% values ranged from 24.7 x 104 – 21.3 x 103 cfu/ml, M50% values ranged from 24.3 x 103 – 4.3 x 103 cfu/ml. In the O25%, values obtained ranged from 24.3 x 103 – 26.3 x 10 cfu/ml, O50% values ranged from 24.7 x 104 – 11.3 x 10 cfu/ml and in P25% values ranged from 24.3 x 103 – 11.3 x 103, P50% values ranged from 24-0 x 103 – 2.7 x 104 cfu/ml. The sample containing P.guineense extract had the lowest bacterial count of 2.7 x 104 cfu/ml at the 7th day of the storage while the sample containing no extract (control) had the highest bacterial count of 42.0 x 103 cfu/ml within the same period of storage. Fungal count were also seen to be high in the unblended (control) samples than in the blended samples. The highest count of fungi was 24.7 x 103 cfu/ml which was seen in the unblended (control) samples and the lowest value was 16.7 x 103 cfu/ml obtained from P50% samples. Also, the microorganisms present in the samples were identified using staining and biochemical techniques. The bacterial organisms identified include Staphylococcus aureus, Pseudomonas sp, Escherichia coli, Bacillus sp, Lactobacillus sp and Proteus sp while the fungal organisms identified were Aspergillus sp and Saccharomyces sp. However, the samples containing P.guineense were better rated in terms of parameters tested. The results of this study indicate that incorporation of P.guineense, O.gratissimum and M.oleifera leaves into zobo drink could be an effective means of improving quality (microbial) and extending the shelf-life of zobo drinks. The study shows the possibility of large scale production of zobo using treatment with these leaves as a safe, low cost means of preservative.

TABLE OF CONTENTS

Cover page

Title page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgements ﾿ iv                                                                                        

Table of contents ﾿ v

List of Figures ﾿ ix

List of Tables ﾿ x

Abstract          ﾿ xi                                                                                              

CHAPTER ONE

1.0   Introduction ﾿ 1

1.1   Aims and Objective ﾿ 4

CHAPTER TWO

2.0   Literature review ﾿ 5

2.1   An Overview of Hibiscus sabdariffa (Zobo) Drink ﾿ 5

2.2    Bacteriological Quality of Beverages ﾿ 6

2.2.1 Control of Microbiological Quality of Beverages ﾿ 7

2.2.2 Hazard Analysis and Critical Control Point (HACCP) ﾿ 9

2.3 Uses of Hibiscus sabdariffa ﾿ 11

2.3.1 Traditional culinary use ﾿ 11

2.3.2 Use in Local and Traditional Food and Medicine ﾿ 11

2.3.3 Animal Feed ﾿ 12

2.3.4 Cosmetic ﾿ 12

2.4 Phytochemistry of Hibiscus sabdariffa ﾿ 12

2.4.1 Nutritional Value ﾿ 12

2.4.2 Bioactive Constituents ﾿ 12

2.5 Biological and Pharmacological Activities of Hibiscus sabdariffa ﾿ 13

2.5.1 Antibacterial, Antifungal and Antiparasite Activity ﾿ 13

2.5.2 Antioxidant Activity ﾿ 13

2.5.3 Hepatoprotective Activity ﾿ 14

2.5.4 Cancer-Preventive Activity ﾿ 15

2.5.5 Anti-Diabetic Activity ﾿ 15

2.6 Overview of Some Important Leaves with Antimicrobial Properties ﾿ 15

2.6.1 Piper guineense ﾿ 15

2.6.2 Moringa oleifera ﾿ 17

2.6.3 Ocimum gratissimum ﾿ 20

CHAPTER THREE

3.0 Materials and Methods ﾿ 24

3.1 Collection of Samples ﾿ 24

3.2 Preparation of Zobo drink ﾿ 24

3.2.1 Blending of Zobo drink with leaf extracts ﾿ 25

3.3 Storage of samples ﾿ 26

3.4 Sterilization of materials ﾿ 26

3.5 Microbiological analysis ﾿ 26

3.5.1 Bacterial isolates ﾿ 26

3.5.2 Fungal isolates ﾿ 27

3.6 Biochemical tests ﾿ 27

3.6.1 Catalase test ﾿ 27

3.6.2 Coagulase test ﾿ 27

3.6.3 Oxidase test ﾿ 28

3.6.4 Sugar fermentation ﾿ 28

3.6.5 Spore staining test ﾿ 29

3.6.6 Gram staining ﾿ 29

3.7 Lactophenol cotton blue stain reaction ﾿ 30

3.8 Physicochemical analysis ﾿ 30

3.8.1 pH determination ﾿ 30

3.8.2 Determination of titratable acidity (%) ﾿ 30

3.8.3 Determination of ascorbic acid (vitamin C) ﾿ 31

CHAPTER FOUR

4.0 Results ﾿ 32

CHAPTER FIVE

5.0 Discussion, conclusion and recommendation. ﾿ 42

5.1 Discussion ﾿ 42

5.2 Conclusion ﾿ 45

5.3 Recommendations ﾿ 45

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