Flavors and Aromatic Compounds in Foods

Flashcards on Flavors and Aromatic Compounds in Foods lecture notes.

Flavor

The most important parameter that maximizes food quality and global competitiveness.

Stability of Flavours during Processing

Traditional flavouring raw materials are produced under rather “harsh” conditions, resulting in the destruction of all sensitive substances, therefore 100% stability is not attainable.

Stability of Flavours during Processing

Modern flavouring raw materials are produced under controlled and careful conditions, resulting in sensitive substances surviving the production process and thus influencing the quality of product.

Factors influencing quality attribute of food aroma

Chemical reactivity of food flavor, environment of food, and food matrix system and its constituents.

Factors affecting the stability of Flavours

Heat treatment, oxidation, and enzyme activity.

Factors affecting the stability of Flavours

Low pH, fat absorption of liposoluble components, and protein reactions.

Physical stability

Evaporation of volatile components, crystallization of non-soluble material, and phase separation.

Chemical stability

Reactions with food components and Reactions of Flavouring components through degradation, rearrangement, oxidation.

Sensory stability

What is the standard sample to compare with, What does the customer expect and remember, How does the customer evaluate the samples.

Thermal Processing Methods

In-Container Sterilization, Aseptic processing and Packaging, Rapid heating and Cooling, Pasteurization (LTLT, HTST, UHT, Sterilization, Various forms of Cooking.

Non-Thermal Processing Methods

High Pressure Processing, Pulse Electric Field, Ohmic Heating, Radio Frequency, Microwave, Ultra Filtration, Irradiation e.t.c

Effect of Thermal Processing

An increase in reaction kinetics accelerates loss of flavor compounds.

Effect of Thermal Processing on Milk

Cooked/Heated/Burnt and stale flavor of milk is due to ketones formation.

Effect of Thermal Processing on Milk

Buttery, milky, coconut like flavors in milk are due to lactones formation from thermal breakdown of hydroxyacids.

Effect of Irradiation on Garlic

Diallyl disulfide reduced significantly when treated with gamma radiation.

Effect of Irradiation on Ginger

No major changes in volatile concentration in gamma irradiated ginger, but after 3 months decrease in a-zingiberene, B-bergamotene, neral, geraneal and a-curcumené were significant.

Effect of High Intensity Pulsed Electric Field on Tomato Juice

PEF-processed tomato juice retained more flavor compounds of trans-2-hexenal, 2-isobutylthiazole, cis-3-hexanol than thermally processed or unprocessed control tomato juice.

Pathways for Chemical changes in flavours during processing

Maillard Reactions, Lipid Oxidation.

Maillard Reactions

When aldoses or ketoses are heated in solution with amines, a variety of reactions ensue, producing numerous compounds, some of which are flavors, aromas, and dark-colored polymeric materials.

Lipid Oxidation

The mechanism of flavor development in heated oils is essentially that of lipid oxidation.

Sun-struck flavour in beer (3-methyl-2-butene-1-thiol formation)

Hop derived isohumulones are decomposed to 3-methyl-2-butenyl radicals due to sunlight exposure. Sulfur-containing amino acids and proteins decompose to SH radicals through riboflavin-photosensitized reactions. These two radical types then combine and form 3-MBT.

Physical Changes in flavour during processing

Flavor products manufactured by spray or vacuum oven drying are often amorphous solids or they contain amorphous particles.

Glass Transition Temperature

At a specific temperature called the glass transition temperature, the viscosity drops by 3-4 orders of magnitude. The solids texture changes from a glassy into a rubbery state.

Citral

Citral, 3,7-dimethyl-2,6-octadienal, is the most important flavor compounds in citrus oils. Because citral is an unsaturated aldehyde, it is highly susceptible to acid-catalyzed cyclization and oxidative degradation, particularly in the presence of light and heat, leading to off-flavor formation, especially in lime and citrus juice products

Allyl isothiocyanate

AITC, 3-isothiocyanato-1-propene, is the major pungent flavor compound naturally found in plants of the Brassicaceae family such as horseradish, mustard, wasabi, and cruciferous vegetables; unstable compound and has been reported to gradually decompose to compounds with a garlic-like odor in water at 37 oC and even at room temperature.

Vanillin

Vanillin, 4-hydroxy-3-methoxybenzaldehyde, commercially called p-vanillin, is a major constituent of vanilla flavor, and is a well-known flavoring agent used in various food industries such as bakery, confectionary, ice cream, fragrance, cosmetics etc.

Potato processing - Methional

It causes the losses of a large amount of methional because it is heat labile and readily decomposes to methanethiol, which oxidizes to dimethyl disulfide.

Microencapsulation

The affinity of the flavour compounds with the food matrix is extremely important because it will affect the flavour delivery process.

Antioxidant

Gallotannin is used to improve the flavour stability of beer.