Chapter 9 :- Flavour

The enjoyment and acceptance of a meal depends to a large extent on a blend of different attributes of food. It is detected by our senses of taste and odour.

Flavour is produced by aromatic chemicals that stimulate the senses of our odour & taste. These stimulating components are synthesized in plant and animals. They may be further modified by cooking and processing.

There are four basic tastes:-

• Sweet
• Bitter
• Salty
• Sour

These tastes are detected by taste buds(10,000). Taste buds are located mainly on the tongue. Odour is detected by extremely sensitive 10 million cells situated in the upper portion of the nasal cavity

The level at which a taste can be identified is called the threshold level.

(A.) Definitions:-

Flavouring-- It is a substance which can impart flavour and is generally used to impart taste or odour or both to a food.

Aroma-- It refers to a pleasant, often spicy odour, fragrance, or smell. 

Flavour-- It is a blend of taste and odour perceptions experienced when food is in the mouth. 

Aftertaste-- It is the flavour that lingers in the mouth after food has been swallowed. 

Flavour intensifier-- It is a compound that enhances the flavour of other foods without contributing any flavour of its own.

Classification of flavours:-

(1.) Natural Flavours:-

• They are usually extremely complex mixtures of many different substances. Sometimes the flavour of natural flavouring agent may depend upon a single substance. Eg:- Clove oil flavour is because of chemical eugenol. It contributes 85% of clove oil.
• Or it may be present in extremely small amounts such as citric in oil of lemon which constitutes 5% of the oil.
• Natural flavouring agents are compound of mainly aromatic organic compounds present as volatile essential oils or as non-volatile constituents.  Such as resins and oleoresins. They are formed in the plant during normal plant metabolism and remains as such the plant is harvested.
• The aroma of onion, garlic, cabbage is mainly due to Sulphur-containing compounds.
• The flavour and aroma of fruits and vegetables are because of the presence of volatile organic chemicals such as esters, aldehydes, acids, alcohols, ketones and ether present as essential oils in natural foods.

(2.) Processed Flavour:-

• The flavour that develops during processing by decompositions, the combination with other compounds, or formation of a new compound.
• The following flavours form during processing of various foods.
• Flavour due to enzyme action

Vegetable cuts (onions, garlic) Odour is because of formation of diallyl disulfide.

• Flavour produced by microbiological action during fermentation of sugar.

Fermentation

   Eg-           sugar ——-yeast——>>alchohol

                    Milk——–bacteria——–>>curd

                    Milk——–bacteria——>>cheese

      

• Flavour formed during cooking and other heat processing.
  Eg:- cooked meat flavour, aroma of freshly baked bread or roasted  Coffee beans

• Undesirable flavours caused oxidation eg: rancidity of oil.

(3.) Added Flavour

• Natural flavour or synthetic flavours are often added to food to increase its acceptability.
• Role of added flavours has gained importance with advancement in technology being used in food industry and development of new products such as bakery and confectionary items, ready to eat foods, beverage and fast food items.
• The flavour which is lost during cooking and processing can be replaced by either of the following methods:-
• Adding natural flavourings and extracts:– Eg:- Natural essence from fruits, essential oils extracted from spices, Vanilla essence is prepared by extracting the essential oil from vanilla pod with the channel.
• Adding synthetic flavours that consist of a blend of chemical which smells like the original substances Eg:-  Vanillin is the synthetic flavour instead of vanilla.
• Synthetic chemicals are blended to match a natural flavour.
• Other substances which contribute towards the flavour of food are sweeteners and flavour enhances.

(B.) Description of food flavours (tea,coffee ,wine,meat,fish, spices):-

TEA

• Tea is the second most widely consumed beverage around the world after water . 
• The popularity of tea as a global beverage rests on its pleasant flavor, mildly stimulating effects, and nutritional properties, which people find appealing and attractive. 
• According to the manufacturing process, tea can be divided into at least three basic types: non-fermented green tea, fully fermented black tea, and semi-fermented oolong tea .
• The flavor of tea can be divided into two categories: aroma, which consists mainly of volatile compounds; and taste, which consists mainly of non-volatile compounds. 
• The volatile aromas are important criterion in the evaluation of tea quality.
• The liquid that results from brewing tea is called the liquor.

Flavour and Aroma of Tea

• The sense of smell and taste are intricately linked together. 
• Tea is filled with natural antioxidants, also known as polyphenols. 
• These provide the health benefits in tea and also a good portion of the taste.
• Polyphenols bind with our saliva and create a dry sensation on the tongue and sides of the mouth.
• They also provide the brisk, tannic (acid) bite that is associated with tea.
•  Also important to note: astringency is a physical sensation, whereas bitterness is a flavor - the two can easily be confused, but they are different. 

COFFEE

• Coffee owes its characteristic flavor to caffeine although by itself caffeine without its aroma has a faint bitter taste. 
• Coffee also contains alkaloids, volatile aromatic products and substances belonging to the phenolic series. 
• It stimulates the central Nervous System. 
• The composition of coffee is – 15.30%-nitrogenous substances 11.40%-fatty matter 70.2%-caffeine.

WINE

• The biggest contributor to flavor is yeast. 
• It is the fermentation process that truly gives a wine its flavors. 
• In order for a yeast to live it has to eat and what it likes to eat most is sugar. In the process, the sugar is digested and ends up as two things—carbon dioxide and ethyl alcohol. Once all the sugar is gone, the yeast stop growing and eventually die. 

MEAT

• Most of meat's flavor develops when it is cooked. The amount of fat in meat influences its flavor, as does a process called the Maillard reaction. Flavor can also be added to meat through brining and marinating.
• The Maillard reaction occurs when the denatured proteins on the surface of the meat recombine with the sugars present. The combination creates the "meaty" flavor and changes the color. 
• The Maillard reaction occurs most readily at around 300° F to 500° F. When meat is cooked, the outside reaches a higher temperature than the inside, triggering the Maillard reaction and creating the strongest flavors on the surface. 
• The molecules of the amino acids and sugars combine to form new aromas and flavors. The Maillard reaction is also responsible for the brown colour of cooked foods.
• It normally occurs at very high temperatures, but if there is a high concentration of sugars and amino acids, then it will occur at lower temperatures. 

FISH

• Fish gets its flavor from the natural oils present in the fish all over its body.
• The higher the fat content, the more powerful the taste, as evidenced in appropriately named species like King Salmon. 
• Colder water increases this fat content and therefore the level of deliciousness. 

SPICES

• Spices give aroma, color, flavor, and sometimes even texture to food.
• Each spice, chile, or herb has specific, unique chemical compounds that create these sensual qualities. 
• When talking about spices, a true spice aficionado simply cannot be limited to just four or five. 
• For these people, there are many more equally identifiable flavor characteristics- cooling (mint, fennel), earthy (cumin, saffron), floral(lemon grass, coriander), fruity(star anise, tamarind), herbaceous(oregano, rosemary), hot(mustard, chilli), nutty(fenugreek seeds, sesame seeds), piney(bay leaf, thyme), pungent(garlic, ginger), spicy(nutmeg, curry leaves) and woody(cinnamon, cloves).
• Spices usually do not have a single flavor profile. 
• For example, the popular spice cumin falls into a few of the flavor profiles as it is both earthy and spicy. Thyme is bitter, floral, herbaceous, and piney.

Key Terms:-

• Bouquet garni:- Parsley stalks, a sprig of thyme and a bay leaf along with a stick of celery (for poultry), rosemary (for red meat), fennel (for fish), bundled together and tied with a string or wrapped in muslin and added to soup, stew, etc.for flavour and removed before the dish is served. 
• Essential oils- Volatile, natural flavouring agents present in plants which are oily but chemically not related to fats and oils. 
• PPM:- Parts per million 
• Seasoning- Traditionally  an item added to enhance the natural flavours of a food without changing its flavour dramatically. Salt is the most common seasoning, although all herbs and spices are often referred to as seasonings. 
• Taste threshold- It is that critical concentration value at which the presence of a taste can be just detected.