Food Packaging

Innovations and Shelf-Life

Rui M. S. da Cruz

• Publisher: CRC Press
• Year: 2019
• Print ISBN: 9780367085742
• eBook ISBN: 9780429663000
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

Food Packaging: Innovations and Shelf-life covers recently investigated developments in food packaging and their influence in food quality preservation, shelf-life extension, and simulation techniques. Additionally, the book discusses the environmental impact and sustainable solutions of food packaging. This book is divided into seven chapters, written by worldwide experts. The book is an ideal reference source for university students, food engineers and researchers from R&D laboratories working in the area of food science and technology. Professionals from institutions related to food packaging.

CHAPTER 1

Protective Packaging for Light-sensitive Foods

María Gabriela Passaretti,^1,2 Mario Daniel Ninago,^3,4 Marcelo Armando Villar^1,2 and Olivia Valeria López^1,5,*

1. Introduction

Consumer expectations and interests in nutritional aspects and visual appearance, when purchasing food, are important factors that should be taken into account to improve the food industry (Gadioli et al., 2013). Currently, food packaging is strongly linked to material transparency, which must not hide the product but enable its visibility through the packaging (Eldesouky et al., 2015). Nevertheless, many food natural components as well as those added during their preparation are susceptible to light, causing the occurrence of photo-degradative and oxidative reactions (Duncan and Chang, 2012). Foods are exposed to several sources of light during their entire chain of production and commercialization. Some common light sources and their locations are (a) sunlight outdoors (storefronts and windows), (b) incandescent lamps (coolers and storage facilities) and (c) fluorescent lamps (processing areas, display cases and preparation zones). Foods are also exposed to other sources of light, such as germicidal lamps used in walk-in coolers and storage area rooms to reduce bacterial and mould counts as well as black lights used to detect the presence of insects, rodent excreta and other kinds of contamination. When light strikes a food packaging, it can be reflected off the material surface, absorbed by the packaging material, scattered and absorbed by the food and transmitted through the food. Particularly, light that is absorbed, mainly leads to functionality loss of food compounds (Duncan and Chang, 2012). In most solid foods, light only penetrates the outer layer and so deterioration occurs only at a superficial level. Meanwhile, in liquid foods, light penetration can be greater and their deterioration is more extensive.

A substance that absorbs light following a photochemical reaction is called photosensitizer (Hussmann Corporation, 2017). Molecules present in food formulations, which are more susceptible to photochemical reactions, are lipids, amino acids and nucleotides that make up fats, pigments, proteins and vitamins (Limbo et al., 2007). Among vitamins, the light-sensitive vitamins are A, B₁₂, D, K and E, as well as folic acid, pyridoxine and riboflavin and regarding pigments, anthocyanins, carotenoids, chlorophylls, myoglobin and haemoglobin are light-sensitive. Amino acids, tryptophan, phenylalanine, tyrosine, and histidine, that are present in foods, degrade during light exposure, while food fats, unsaturated fatty acids and phospholipids usually suffer oxidation due to light. In Fig. 1 are shown the most common photosensitizers present in food products.

Foods’ light sensitivity depends on many factors, including the strength of the light source and type of light that it emits, besides light-source-food distance, exposure time, optical properties of packaging materials, oxygen concentration inside the packaging and storage temperature (Chiste et al., 2010; Duncan and Hannah, 2012; Mestdagh et al., 2005).

Fig. 1. Most common photosensitizers present in food products.

Changes in foods induced by photochemical reactions usually start when light is absorbed by a product component that will directly undergo chemical reaction or one food component that generates a product, which undergoes a reaction catalyzed by light. These undesirable reactions in foods cause nutritional loss and produce off-flavor, toxic by-products and colored compounds during product storage and marketing, making them less acceptable or unacceptable to consumers (Barrett et al., 2010).

Susceptibility of food compounds to light exposure is mainly attributed to the presence of electrons of conjugated bonds in their chemical structure, which require very little energy to trigger a reaction. Since all light emitted is a form of energy, the higher the input of energy the more rapid the potential degradation (Hussmann Corporation, 2017). Photosensitizers are mostly activated in the ultraviolet (UV) and the blue/green region of the visible spectrum and are shorter with more energetic wavelengths. Oxidation reactions can be carried out by either diradical triplet oxygen or non-radical singlet oxygen, which can be formed from triplet oxygen during photosensitized reactions (Min and Boff, 2002). Photochemical reactions are impossible to eliminate because foods are exposed to various light types and intensities throughout their supply chain processes: post-harvesting, transport, primary and/or secondary processing, packaging and distribution. Once a food photosensitizer molecule absorbs light, the cascade of reactions cannot be avoided. Thus, it is relevant to obtain knowledge and comprehension about these photochemical reactions to give well-founded practical advice to the industry on how to minimize photo-oxidation through packaging and retail (Wold et al., 2009). In this way, the use of a packaging material that protects food from light exposure is one of the most effective means of preventing light-induced chemical spoilage.

Natural pigments, such as anthocyanins, carotenoids, betalains and chlorophylls have low light-stability and cause food discoloration (Cortez et al., 2017); particularly anthocyanins, which are stable under acidic conditions, but under normal processing and storage conditions, they transform to colorless compounds and subsequently to insoluble brown pigments (Arslan, 2015). In the case of carotenoids, the same extensive conjugated double-bond system, that makes these natural pigments powerful antioxidants, also makes them susceptible to oxidation (Boon et al., 2010). In accordance with Schwartz et al. (2017), due to the many double bonds in carotenoids structure, their oxidation may result in several products from isomerization to extensive molecule cleavage, decrease or loss in the provitamin activity. Besides, light has been shown to degrade betanin, a type of betalains, by around 15 percent in six days at 15°C (Kaimainen, 2014).

Photochemical reactions could liberate a wide range of volatile compounds, which are responsible for off-flavors and off-odors (Ball, 2006). For example, off-flavor in milk is the result of fats’ oxidation to aldehydes and degradation of sulfur-containing amino acids (Brothersen et al., 2016). These reactions are facilitated when the product is exposed to near-UV and visible light from any source, such as sunshine, fluorescent light, or light-emitting diodes.

In some cases, food compounds’ degradation leads the formation of toxins, which are harmful to health (Rather et al., 2017). In accordance with Lu and Zhao (2017), photo-oxidation of phytochemicals can cause a series of problems, such as sensory quality change and even the generation of hazardous and noxious substances. For example, hydroperoxides produced by oxidative reactions are important intermediates that may cause off-flavor and even toxic compounds.

Moreover, some chemical reactions induced by light cause loss of essential nutrients, such as vitamins and food browning (Rahman, 2007). In accordance with this, one nutrient abundant in milk that is highly light-sensitive is riboflavin (vitamin B₂), which is destroyed when exposed to light and produces by-products responsible for rancid milk. This degradation leads to the formation of free radicals, superoxide and singlet molecular oxygen, which degrade other nutrients, such as vitamin C (Francis and Dickton, 2015).

Nowadays, bioactive substances are being intensively studied due to their human health benefits (Barba et al., 2017). Since bioactives typically occur in small quantities in foods, the intake of a specific bioactive could be less than the dose that can exert a specific health effect (effective dose). To overcome this, the food industry is developing new products containing higher concentrations of selected bioactives. These bioactive-enriched foods (BEF) are also known as functional food products, which have a potentially positive effect on health. However, photo-degradation or oxidative reactions of bioactive compounds can reduce nutritional and health advantages of these functional foods (Duncan and Chang, 2012).

The extent of these undesirable changes in food products depends on many factors, including food composition and light source. Not all types of natural or artificial lights are equally absorbed or equally destructive. The effects of light on selected foods are described below.

Raw meat exposed to oxygen typically has an attractive red color. When exposed to light in the UV wavelengths for prolonged period, the fats become rancid (Nerin et al., 2006). While not a health issue per se, a perceived loss of quality due to deteriorating color, odor and taste does constitute a serious threat to the product’s marketability. Processed or cured meats, such as luncheon a...

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• Table of Contents
• 1. Protective Packaging for Light-sensitive Foods
• 2. Packaging Biodegradability: Trends in Food Industry Applications
• 3. New Trends in Smart and Intelligent Food Packaging
• 4. Value-added Utilization of Fruit and Vegetable Pomace in Food Packaging
• 5. Bio-based Materials Inspired from Brazilian Cerrado Wastes
• 6. Fish-gelatin and Carob Seed Peel By-product for Developing Novel Edible Films
• 7. Biodegradable Polymer Blends for Food Packaging Applications
• 8. New Advances in Active Packaging Incorporated with Seaweeds for Food Preservation
• 9. Edible Polymers for Shelf-life Extension of Perishables: An Insight into Films and Coatings
• 10. Future Ventilated Packaging Design: Novel Modeling Approaches and Integrated Multi-criteria Performance
• Index