Food Chemistry

A Laboratory Manual

Dennis D. Miller, C. K. Yeung

• Verlag: Wiley
• Jahr: 2022
• ISBN:
  9781119714606
• Auflage: 2
• Thema: Technology & Engineering
• Thema: Food Science

FOOD CHEMISTRY

A manual designed for Food Chemistry Laboratory courses that meet Institute of Food Technologists undergraduate education standards for degrees in Food Science

In the newly revised second edition of Food Chemistry: A Laboratory Manual, two professors with a combined 50 years of experience teaching food chemistry and dairy chemistry laboratory courses deliver an in-depth exploration of the fundamental chemical principles that govern the relationships between the composition of foods and food ingredients and their functional, nutritional, and sensory properties. Readers will discover practical laboratory exercises, methods, and techniques that are commonly employed in food chemistry research and food product development.

Every chapter offers introductory summaries of key methodological concepts and interpretations of the results obtained from food experiments. The book provides a supplementary online Instructor's Guide useful for adopting professors that includes a Solutions Manual and Preparation Manual for laboratory sessions.

The latest edition presents additional experiments, updated background material and references, expanded end-of-chapter problem sets, expanded use of chemical structures, and:

• A thorough emphasis on practical food chemistry problems encountered in food processing, storage, transportation, and preparation
• Comprehensive explorations of complex interactions between food components beyond simply measuring concentrations
• Additional experiments, references, and chemical structures
• Numerous laboratory exercises sufficient for a one-semester course

Perfect for students of food science and technology, Food Chemistry: A Laboratory Manual will also earn a place in the libraries of food chemists, food product developers, analytical chemists, lab technicians, food safety and processing professionals, and food engineers.

1
Acids, Bases, and Buffers

1.1 Learning Outcomes

After completing this exercise, students will be able to:

1. Explain the roles of acids and bases in food products.
2. Measure the pH of selected food products.
3. Prepare and evaluate a buffer system.
4. Measure the buffering capacity of a common beverage.

1.2 Introduction

Many food components may be classified as acids or bases due to their capacity to donate or accept protons (hydrogen ions). These components perform numerous important functions including flavor enhancement, control of microbial growth, inhibition of browning, alteration of texture, prevention of lipid oxidation, and pH control.

Acids and bases are key metabolites in living plant and animal organisms, for example as intermediates in the TCA cycle, and are mostly retained when the plant is harvested or the animal is slaughtered so they are naturally present in foods. They may also be added during processing or synthesized during fermentation to produce desired characteristics in the final food product.

The concentration and relative proportion of acids and bases determine the pH of a food, an extremely important characteristic. pH can affect the flavor, color, texture, stability, and behavior in food processing situations. For example, commercial sterilization of acid foods (pH less than 4.6) [1] can be achieved under milder processing conditions than in foods with a higher pH.

1.2.1 Acids

Acids serve a variety of functions in foods including flavor enhancement, control of microbial growth, protein coagulation, emulsification, control of browning, buffering action, and metal chelation (to control lipid oxidation). All acids have a sour taste but different acids produce distinctively different sour flavors. Thus, it is not enough to simply add any acid when attempting to produce a characteristic sour flavor in a food. Table 1.1 gives structures and pK values of some common food acids.

Table 1.1 Acids common in foods: structures and pK_a values.

Substance	Structure	pKa	Food found in
Acetic acid		pK = 4.75	Vinegar, figs
Adipic ...