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Development of Natural Antioxidant Active Polymer Package from Extracts of Monodora myristica (Ehuru) for Lipid Food Preservation
ABSTRACT
A natural antioxidatant active polymer package film was developed for lipid food preservation. Three active package films were produced, namely: film containing only ehuru antioxidant extract (EAE), α-tocopherol (AT) and a blend of EAE/AT using casting method. Different percentage compositions (0 – 5% w/w) of EAE were incorporated into polysulphone (PSF) resin, while 5% AT was incorporated into PSF resin which served as standard. A 5% equal combination of EAE/AT was also added to PSF to produce package film. Mechanical, thermal, morphology and barrier properties of developed films as well as the pure PSF film were determined and compared. The antioxidant ability of the developed films was investigated using 2,2- Diphenyl-1-picrylhydrazyl (DPPH) method. The ability of the films to stabilise lipid (peanut oil) against oxidation was tested by packaging peanut oil with the active films. The peroxide value (PV) and p-anisidine value) of the actively packaged and stored peanut oil were determined. Results of the barrier properties showed that the rate of permeation of gas in the EAE active films was shown to be reducing significantly (from 0.1256 to 0.0277)cm3/s as concentration of EAE incoporated in the film increased, while films with blend of EAE/AT produced higher permeable films of (0.1079 cm3/s ). AT film was the most permeable (0.2209 cm3/s). The spectrum of the FT-IR analysis confirmed the presence of esters, amides and amines in the absorption peaks of 3526, 3302.4 and 3697.5 cm-1. Absorption peak of 1736.9 cm-1 for the ester and 1684.8 cm-1 for amide. The SEM microstructure revealed that the porous film of the pure PSF reduced as concentration of the EAE added increased from 0% – 5%. The incorporation of 5% EAE , produced very smooth and homogenous surface film without apparent phase separation. The melting point of EAE active film was established at 210 oC compared to 230 oC for the pure PSF. The AT active firm recorded a higher melting temperature of 247 oC. The oxidation results showed a significantly (p < 0.05) lower rate increase in oil samples packaged with the developed films than the control sample. Results also revealed that at the end of nine weeks of storage, peanut oil packaged with active film containing only EAE natural antioxidant showed the lowest lipid oxidation by recording the lowest peroxide and p-anisidine values of 9.82±1.50 meq/kg and 30.45±0.00 respectively. The effect of concentration of the EAE on the oxidation of the peanut oil showed that their is no signifcant difference (p > 0.05) in the 2.5% and 5% EAE on the PV and P- anisidine values of the packaged oil sample, hence concentration between 2.5 and 5% could be used for the active film. Considering the mechanical properties of the active package, 5% EAE produced the most flexible film with percentage elongation at break (EAB) of 3.221% and best antioxidant activity of 48.097%. The overall results showed that the developed Ehuru antioxidative package had demonstrated the potential of slowing down the lipid oxidation and therefore could be used to preserve lipid foods like peanut oil.
Key words: Active Polymer package, Natural Antioxidatant, Monodora myristica, Spice extract, Lipid preservation
TABLE OF CONTENTS
PAGE
Title page i
Certification ii
Dedication iii
Acknowledgment iv
Abstract v
Table of Contents vi
List of Tables x
List of Figures xiii
CHAPTER ONE: INTRODUCTION
1.1 Background Information 1
1.2 Problem Statement 4
1.3 Objectives of Study 5
1.4 Justification of Study 6
1.5 Scope of Study 6
CHAPTER TWO: LITERATURE REVIEW
2.1 Introduction to Food Packaging 7
2.1.1 Functions of Food Packaging Materials 7
2.2 Criteria for Selection of Food Packaging Materials 10
2.3 Types of Packaging 10
2.4 Food Grade Polymeric Packaging Materials 10-13
2.5 Barrier Packaging Materials 14-15
2.6 Active Packaging 15
2.6.1 Active Packaging using Sachets and Pads 17
2.6.2 Active Packaging Materials Containing Active Components 18
2.6.3 Active Packaging Materials Containing Enzymes 19
2.6.4 Active Packaging Materials Containing Anti-microbial Systems 19-20
2.7 Lipid Oxidation in Food 21
2.7.1 Hydrolytic Rancidity 21
2.7.2 Oxidative Rancidity 22-24
2.7.3 Free Radicals 24-27
2.7.4 Measurement of Lipid Oxidation 28-31
2.8 Antioxidant (AO) 33’
2.8.1 Classification of Antioxidants 32-33
2.8.2 Synthetic Antioxidants 33-35
2.8.3 Natural Antioxidants 35-38
2.8.3.1 Vitamin E (Tocopherols and Tocotrienols) 38-40
2.8.3.2 Spices and Herbs 41
2.9 Phytochemicals 45
2.9.1 Classes of Major Phytochemicals and Food Sources 46
2.9.2 Phytochemical Metabolism in Human 48
2.9.2.1 Polyphenols 48
2.9.2.2 Flavonoids 49
2.10 African nutmeg “Ehuru” (Monodora myristica) 52-54
2.11-Tocopherol as a Chain Breaking Antioxidant 54
2.12 Quercetin 56
2.13 Prooxidant action of an antioxidant 58
2.14 Review of Previous and Related Researches on Natural
Antioxidant (NOA) used in active Packaging 58
2.14.1 Pure standards of natural AOs 60-62
2.14.2 Antioxidants from Cereals 62
2.14.3 Antioxidants from Crustaceans 62
2.14.4 Natural Antioxidants (NAO) active film from spices 63
2.14.4.1Antioxidants from Ehuru (Monodora myristica) 64
2.15 Measurement of antioxidants 65
2.15.1 DPPH scavenging assay 65
2.15.2 ABTS radical cation decolorization assay 66
2.15.3 Hydrogen peroxide scavenging (H2O2) assay 66
2.15.4 Nitric oxide scavenging activity 67
2.15.5 Reducing power method (RP) 67-68
2.15.6 Hydroxyl radical scavenging activity 68-69
2.16 Antioxidants as Polymer Anti-degradants 70
2.17 Plastcizers in bio polymers 70
2.18 Method used in producing active polymer film 71
2.18.1 Active polymer using coating process method 71
2.18.1 Active Polymer using Solvent Casting Method 71-72
2.18.3 Active Polymer using film Extrusion Method 72-74
2.19 Migration in Polymeric Packaging Materials 75-77
CHAPTER THREE: MATERIALS AND METHOD
3.1 Materials 78
3.2 Methods 79
3.2.1 Preparation of the Antioxidant Spice Extract 79
3.2.2 Production of Test Peanut oil 79
3.2.3 Preparation of Active Packaging Material 79-80
3.2.4 Packaging of the Peanut test oil sample in the active films 81
3.2.5 Chemical Analysis of the Extract 81
3.2.5.1 GCMS Analysis of Ehuru Spice Extract 81
3.2.6 Active Package Analyses 82
3.2.6.1 Tensile Mechanical Properties 82
3.2.6.2 FTIR Characterization of the active film 83-84
3.2.6.3 Thermal Properties; DSC Analysis 83
3.2.6.4 Barrier Properties (Permeability Properties) 83
3.2.6.5 Morphological analysis 84
3.2.6.6 Radical scavenging (antioxidant) activity of the active film 84
3.2.7 Active package test on lipid food 85
3.2.7.1 Determination of oxidation rate of packaged peanut oil 85
3.2.7.2 Peroxide value 85
3.2.7.3 P-anisidine value 86
3.2.8 Experimental design 87
3.2.9 Statistical analysis 87
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Results 89-107
4.2 Discussion 108
4.2.1 Phenolic Components Identified in Ehuru Extract 108-109
4.2.2 Mechanical Properties (Tensile stress) 109-110
4.2.3 Barrier property of the active films 111
4.2.4 Thermal analyses of the active films 111-112
4.2.5 Fourier transform infrared spectroscopy (FTIR) analysis of the antioxidant active films 112-113
4.2.6 SEM morphology of the antioxidant active film 113-114
4.2.7 Oxidative stability of EAE actively stored peanut oil 114-118
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION
5.1 Conclusion 120
5.2 Recommendation 121
5.3 Contribution to Knowledge 121
References 123-138
Appendix 141-164
CHAPTER ONE
INTRODUCTION
1.1 Background Information
Food losses due to oxidation constitute a great economic challenge for the food industry and consumers alike. Food spoilage as a result of oxidation is characterised by alterations of nutritional and sensory characteristics of food such as production of off-flavours and off-odours. It also involves undesirable changes in texture, colour and chemical changes (production of radicals) that can harm human. As a result, new packaging technologies have been studied in order to provide good quality, safer food products with longer shelf life (Otoni, Espitia, Avena-Bustillos, & McHugh, 2016). Among these technologies is Modified Atmosphere Packaging (MAP). This system of packaging involves changing the gaseous atmosphere surrounding a food product and employing packaging materials with appropriate level of gas barrier to maintain the changed atmosphere. It is a post-harvest technique used to increase the shelf life of fresh produce (Joshi, Warbi, Valverde, Tiwari, & Cullen, 2018). Another new packaging system is active packaging, where the packaging material interacts with the packaged food in a desirable way, overcoming the passive role of just containment and protecting food products from the outside environment (Ahmed et al., 2017)
Active packaging with antioxidant properties have taken the centre focus of food packaging technology research because of the fact that oxidation and microbial contamination are the most significant problems affecting food quality and safety. Active packaging systems are special food polymer packaging materials that contain significant amounts of (active) components that provide desirable preservative roles to food products. The process is termed “active packaging” because the package act as an antioxidant amongst its other functions. (Arrieta, Lopez, Hernandez, & Rayon, 2014; Shojaee-Aliabadi et al., 2013)
This new trend came into place because of several reports that the direct addition of natural antioxidants into the bulk food do act as pro-oxidant while chemical preservatives have been implicated to be detrimental to human health. These adverse effectsrange from the carcinogenic effects of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) to interference of BHA in the human hormone (endocrine) system (Samsudin et al., 2017; Tátraaljai, Kirschweng, Kovács, Földes, & Pukánszky, 2013)
Alot of studies have been conducted on the utilization ofplant polyphenols as alternatives to chemical antioxidant agents (BHT and BHA).These chemical antioxidant agents are reported to be susceptible to migration during heating or long term storage because they are not covalently bound to the polymer. Therefore, there is this growing interest in the scientific community in finding and replacing chemical antioxidants with natural ones as preservatives in food and food contact materials, These natural antioxidants are considered safe since they belong to the group of foods generally regarded as safe (GRAS) (Doshi, Adsule, & Banerjee, 2015).
Lipid oxidation is considered a principal means of deterioration or spoilage of oily foodstuffs such as vegetable oils, animal fats, flavourings, nuts, processed meats and snack products, etc. The need for antioxidants is not only limited to high-lipid foods but also includes products such as cereals which contain only 25% lipid components. Oxidation not only negatively influences the chemical, sensory (flavor, texture and color), and nutritional properties of edible oils and fatty foods, but also produces free radicals and reactive oxygen species (ROS). These free radicals and ROS have been reported to be associated with most health problems encountered in man like carcinogenesis, inflammation, aging, cardiovascular disorders, motility, chemotherapy response, and drug resistance ( Huang & Freter, 2015). Oxidation therefore, plays a very important role in determining what a particular oil or fat can be used for as well as its shelf life (Anwar, Chatta, & Hussain, 2007; Das Sarma, Mallick, & Ghosh, 2010; Tian, Decker, & Goddard, 2013).
Hydroperoxides, which are the first products of autoxidation, are colourless, tasteless, and odourless. These products break down to low-molecular-weight compounds that are characterized with rancid flavours and odours. A lot of food additives in combination with food packaging strategies are presently employed to prevent these harmful oxidative reactions within food systems.
Synthetic (BHA, BHT) and natural antioxidants (ascorbic acid, tocopherol) are added directly to foods as primary antioxidants, which donate hydrogen atoms to quench peroxide radicals before they can further react with unsaturated lipids. Phenolic antioxidants are stable due to the fact that they form a radical with very low reactivity, due to delocalization of their unpaired electron on the aromatic ring. With this, they exhibit no further potential to react with lipids after hydrogen abstraction unlike their oxidation radicals. Even though lipid foods have some quantity of inherent defence system (antioxidant) that resists oxidative damage due to ROS, supplementing this natural defence mechanism with external antioxidants offers a better protection against the risk of certain oxidative deterioration.
It has been established that there is great antioxidant potential and health benefits contained in natural products like green tea, rosemary, oregano,spices like ehuru, herbs, clove, blueberries, barley husk, and other plants (Colon & Nerin, 2012;
Pereira De Abreu, Losada, Maroto, & Cruz, 2010; Tátraaljai et al., 2013) Several works have been reported on the incorporation of tocopherol (Vitamin E) and ascorbic acid (Vitamin C) as active agents into a polymer (Gemili,
Yemenicioğlu, & Altınkaya, 2010; Noronha, De Carvalho, Lino, & Barreto, 2014; Siró et al., 2007). Other works on natural antioxidants from leafy spice extracts such as green tea extracts (Camellia sineensis L.) have been reported by Colon & Nerin (2012) and López-de-Dicastillo et al., (2011), while works on rosemary (Rosmarinus officinalis L.), have been reported by Sánchez-Escalante, et al., (2001); extracts of oregano also known as “thyme” (Origanum vulgare L.) was reported by (Camo, Lorés, Djenane, Beltrán, & Roncalés, 2011) mint (Mentha spicata L.) and extracts of sage (Salvia officinalis L.) as active agents incorporated into polymer food packaging for preservation have all been reported.
Other works dwelt on the incorporation of root spices such as Cucumen (turmeric ) and Ginger (Zingiber officinale Rosc.), into polymer food packaging materials. (Gemili et al., 2010). However, till date, no work on the use of seed spices has been reported as active agent incorporated in polymer film packaging material. Interestingly, Ehuru (Monodora myristica) extracts has been reported by researchers to exhibit a potent antioxidant activity and also effectiveness for achieving high sensory scores and lowering lipid oxidation (Akinwunmi & Oyedapo, 2013; George & Osioma, 2011; Okonkwo & Ogu, 2014). Therefore, there is need to investigate the performance of this indegenous seed spice (Ehuru) as active additive into polymer packaging material.
1.2 Problem Statement
Most of the food being packaged with polymeric materials are faced with oxygen and UV light permeation which leads to free radical chain formation, with consequent food deterioration. Chemical/synthetic antioxidants; butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) used in preserving foods have been implicated in carcinogenicity, and hence a safety challenge to consumers.
In most foods, the surface growth of peroxides as a result of oxidation is the major cause of lipid food spoilage. Since oxidation is a chain reaction process, an extremely proactive approach must be taken to prevent or limit the initiation step. This implies that methods that can eliminate surface peroxides as soon as they are formed would greatly slow downthe process of oxidation and ensure shelf-life extension. This approach would eliminate the need for further addition of antioxidants in the bulk of the food. This research is aimed at producing an antioxidative active package that would adress this probem
1.3 Objectives of Study
The main objective of this research is to develop a natural antioxidant active polymer package from extracts of Monodora myristica (ehuru) for Lipid food preservation.
The specific objectives are as follows:
- To determine the phenolic compositions of the spice
- To prepare the ehuru extract from the seed spice
- To develop natural antioxidant active Polysolfone (PSF) packaging films.
- To determine the antioxidative capacity of the developed active packaging films
- To establish the effect of the natural antioxidant additive on the mechanical, thermal and permeability properties of the polymer food packaging materials
- To assess the effectiveness of the active package in reducing lipid oxidation in food
1.4 Justification of study
Having observed the negative effects of oxidation, leaching and safety of the conventional antioxidants in food packaged with polymer materials, there is need to produce novel polymeric packaging material. These materials containing natural antioxidative fillers may be safe, help to reduce food wastage, food poisoning and allegic reactions because no chemical additives or preservatives are added into the food. The natural antioxidants when released into food, increase the content of bioactive compounds in the food products instead of constituting a toxicological risk as occurs with synthetic antioxidants. The use of natural antioxidants from Ehuru will add industrial value to these indegenous spice. It will also promote shelf stability of packaged oily foods especially in the rural areas that lack electricity.
1.5 Scope of study
The scope of this project covers the production and characterisation of polymer PSF active film using ehuru as the source of natural antioxidant. Also covered is the storage study on the actively packaged fresh peanut edible oil packaged with the developed active polymer film, in order to monitor the oxidation rates of the packaged oil. The effect of concentrations of the natural antioxidants on the mechanical, thermal and permeability properties was also covered in the work.
Development of Natural Antioxidant Active Polymer Package from Extracts of Monodora myristica (Ehuru) for Lipid Food Preservation