Food Quality and Shelf Life

Charis M. Galanakis

• Publisher: Academic Press
• Year: 2019
• Print ISBN: 9780128171905
• eBook ISBN: 9780128171912
• Topic: Technology & Engineering
• Subtopic: Food Industry
• Index: Technology & Engineering

Food Quality and Shelf Life covers all aspects and challenges of food preservation, packaging and shelf-life. It provides information on the most important pillars in the field, starting with active and smart packaging materials, novel technologies, and control tools in all stages between production and consumer. The book gives emphasis to methodological approaches for sensory shelf-life estimation and the impact of packaging on sensorial properties. Researchers and professionals alike will find this reference useful, especially those who are interested in the performance evaluation of future packaging for fresh produce in the cold chain and temperature management in the supply chain.- Presents insights regarding new trends in emerging technologies in the field- Includes hot topics, such as modified atmosphere packaging and active materials to improve shelf-life- Provides shelf-life assessment and modeling methodologies and accelerated shelf-life testing

1

Food quality changes during shelf life

E. Moschopoulou*; G. Moatsou*; M.K. Syrokou^†; S. Paramithiotis^†; E.H. Drosinos^† * Laboratory of Dairy Research; Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
^† Laboratory of Food Quality Control and Hygiene; Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece

Abstract

This chapter deals with the various quality changes that occur during the shelf life of foods and tend to limit it. It explains how intrinsic factors, that is, originating from food, like water activity, pH, and chemical and microbiological composition, and extrinsic factors, like storage conditions and packaging, may affect the changes of food quality during shelf life in general. Then, two case studies are presented: the influence of both intrinsic and extrinsic factors on the quality changes of dairy products, with emphasis on those occurring in cheese, during shelf life. In addition, the quality changes of various meat products, like fresh meat, cured meat, and fermented milk, during shelf life are discussed.

Keywords

Shelf life factors; Milk shelf life; Yoghurt shelf life; Cheese shelf life; Fresh meat shelf life; Cured meat products shelf life; Fermented meat products shelf life

Chapter outline

• 1 Introduction
• 2 Intrinsic factors affecting food shelf life
  • 2.1 Ingredients
  • 2.2 Water activity (a_w)
  • 2.3 pH
  • 2.4 Microflora
  • 2.5 Enzymes
  • 2.6 Redox potential (E_h)
• 3 Extrinsic factors affecting food shelf life
  • 3.1 Processing
  • 3.2 Storage conditions
  • 3.3 Packaging
  • 3.4 Logistics and retail issues
• 4 Quality changes during shelf life of dairy products
  • 4.1 Processed fluid milk
  • 4.2 Yoghurt
  • 4.3 Cheese
  • 4.4 Butter
  • 4.5 Milk powders
  • 4.6 Quality changes during shelf life of meat products
  • 4.7 Fresh meat
  • 4.8 Cured meat products
  • 4.9 Dried meat products
  • 4.10 Fermented meat products
• 5 Conclusion
• References
• Further reading

1 Introduction

According to European Union legislation (EC Regulation No. 1169/, 2011) shelf life is referred to as the “date of minimum durability” and requires that the shelf life of a foodstuff be indicated by either a “best before” date or a “use by” date. The “best before” date, is the date until which a foodstuff retains its specific properties, for example, taste, aroma, appearance, and any specific qualities that are related to the product, providing the product has been stored appropriately and the package is unopened. The “use by” date is related to the safety and is the date that afterwards a foodstuff may not be safe.

In practice, the term “shelf life” describes the duration of consumer’s acceptance of a foodstuff. From this point of view, the end of shelf life differs among products and classifies them into those having intermediate or long shelf life and those having short shelf life. Therefore, all foods either with the “use by” or with the “best before” labeling have a certain shelf life, which depends firstly on their specific quality characteristics and secondly on their environmental conditions. In other words, labeling reflects the fact that during shelf life, quality characteristics are not stable and, consequently, foods deteriorate. The quality changes that may occur in food are presented in Table 1.

Table 1

Changes of food quality occurred during shelf life

Type of change		Examples of foods
Physical changes	Moisture gain or loss	Fresh fruits and vegetables, cheeses
	Water vapor transfer, ice sublimation	Frozen products, e.g., ice cream
	Loss of characteristic flavor, development of undesired odor or flavor (“taint”)	Juices, chocolate, tea leaves
	Loss of carbon dioxide	Carbonated drinks
	Crystallization and textural changes	Milk powders, toffee
	Emulsion destabilizing and breakdown	Butter, margarine
	Syneresis	Yoghurt products, jams, sauces
Chemical and biochemical changes	Chilling injury	Fruits and vegetables
	Hydrolysis of fatty acids	Butter, whole milk powder, cheeses, cereal grains
	Oxidation of fats, proteins, pigments, vitamins	Cereals (wheat, barley, maize), oilseeds (soya), fish, meat, milk
	Nonenzymic browning	Dehydrated fruits and vegetables, evaporated and dry milk products
	Enzymic browning	Precut fruits and vegetables
	Off-flavors, oxidative discoloration, interactions between food and packaging	Foods in tinplate cans
Light-induced changes	Photo-oxidation of vitamins, light induced oxidation, color fading	Milk, snacks, bakery products
Microbiological changes	Growth of pathogenic microorganisms, microbial toxins	Fish, meat products, poultry, milk, cheeses
	Microbial spoilage by Gram-negative, spore-forming bacteria, Enterobacteriaceae, NSLAB, yeasts, and molds	Fish, meat products, poultry, milk cheeses

Based on Man, D.C.M., 2015. Shelf Life, second ed. Wiley Blackwell, UK.

Factors in food quality changes may be physicochemical, like pH and a_w, microbiological, like spore-forming bacteria, or organoleptic, referred to as intrinsic factors; or they may be the storage conditions, the packaging etc., referred to as extrinsic factors.

2 Intrinsic factors affecting food shelf life

2.1 Ingredients

Proteins, fats, carbohydrates, and vitamins are the food components that exhibit the most important changes during shelf life under the influence of microflora, enzymes, and processing conditions. Shelf life of fatty foods is much affected by their concentration in unsaturated fatty acids, since these acids are prone to oxidation during production and storage, especially in the absence of antioxidant substances such as phenolic compounds, alpha-tocopherol, or ascorbic acid. For example, the oxidation degree of olive oil is greatly affected by the ratio of saturated/unsaturated fatty acids and the total phenolic compounds. To extend or limit shelf life of fatty foods, antioxidants are used. Other substances that may be added in other foods to inhibit quality deterio...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Preface
• 1: Food quality changes during shelf life
• 2: Moisture properties and stability of novel bioactive ingredients
• 3: Emerging cold pasteurization technologies to improve shelf life and ensure food quality
• 4: Natural antimicrobial agents to improve foods shelf life
• 5: Improving the shelf-life of food products by nano/micro-encapsulated ingredients
• 6: Survival of probiotics in functional foods during shelf life
• 7: Modified atmosphere packaging for food preservation
• 8: Intelligent packaging to improve shelf life
• 9: Food packaging and migration
• 10: Assessment of fresh fruit and vegetable quality with non-destructive methods
• 11: Sensory shelf life estimation
• 12: Accelerated shelf life testing
• Index