STUDY OF RANCIDITY IN FISH PRODUCTS

The Project Title is: Study of rancidity in fried fish and fish products, the multinationals vs local cafes (SMEs).

The Project Title is: Study of rancidity in fried fish and fish products, the multinationals vs. local SME's

Introduction

Oil of fresh Trachurus trachurus had a very high acid value (34.2) relative to the other two (12.8 and 19.5) suggesting high content of fatty acids which comprise of essential fatty acids and other fatty acids necessary for human development. These fatty acids reduced drastically when fish samples are subjected to frying and roasting. The acid values of oils from fried fish samples were low and similar compared to highly different values obtained for oils from other treatment methods. The low acid values recorded for the fried and roasted samples can be because frying and roasting reduce hydrolysis but boiling does not. This hydrolysis resulted in the reactions of the hydroxyl and carbonyl groups of the acids in the oil thereby reducing the fatty acid content of the oil (Makinson & Greenfield, 1987). High moisture content (which was obtainable with the fresh and boiled samples) led to hydrolysis when temperature increased and this further led to the breakdown of essential fatty acids and reaction of the alkyl group of the fatty acids resulting in the production of undesirable, off-flavour hexanal and other rancidity products.  Low moisture content is in keeping with the preservation of the quality of the fish and prevention from spoilage.

Oxidative rancidity is a complex process that is thought to occur in phases: (1) initiation, (2) auto-oxidation and (3) termination. During each phase, the formation of products increase and decrease over time, as shown in Figure 1. Hydroperoxides form when oxygen and unsaturated fatty acids combine in the presence of a catalyst (such as iron, copper, heat, light, enzymes, etc.) during the initiation phase. These peroxides are reactive and can combine with other fats to form additional reactive products during auto-oxidation. Hydrocarbons, aldehydes and ketones are formed during the termination or final phase. These compounds are volatile, but relatively unreactive.

Literature Review

Multinational Resturants selling Fish Products

McDonald's business began in 1940 as a restaurant opened by two brothers, Dick and Mac McDonald in San Bernardino, California. The founding of the present day McDonald's Corporation dates back to April 15, 1955 when a franchised restaurant was opened by Ray Kroc in Illinois. Kroc was responsible for leading the corporation to worldwide expansion. McDonald's became a public corporation, listed on the stock market in 1965. McDonald's eventually has dominated the fast food industry for years as the market leader. It is one of the world's largest chain of fast food restaurants, found in 119 countries with over 31,000 restaurants worldwide and more than 1.5 million employees. The chain serves about 47 million customers a day. McDonald's primary products include hamburgers, cheeseburgers, French fries, soft drinks, breakfast items, and desserts. It has recently added to its menu coffee, salads, wraps, and fruit. McDonald's earns revenue in several roles as a franchiser of restaurants, operator of ...