Beef: Nutrition, Microorganisms and Preservation

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Introduction

Beef is the kitchen name for meat from animals in the bovine subfamily like bison, African buffalo and the domestic cow. Normally it is harvested from bulls, cows, steers or heifers. The meat has various preparation methods either as roasts, steak or ribs. It could be processed into corned beef or timed and mixed with other meat to make sausages. The oxtail, liver, entrails, liver, heart, brain kidneys and testicles are also eaten (Martin, S. 2011).

In recent years, this food has been facing a lot of negative publicity. This has mostly been associated with most people’s choice to cut any red meat entirely from their diets. Though it is true that some beef cuts have high concentrations of saturated fats, the food’s nutritional values cannot be gainsaid.

Nutritional content

Proteins

Beef is a superior source of proteins which is an essential part of any meal. Proteins are used in muscle building, the maintenance of organs and skin, nails and hair regeneration. Beef produces protein of a high quality which is complete. The completeness of beef protein implies that it contains the whole spectrum of amino acids that the body critically needs and is ready to use. 10 to 11.5 ounces of beef contains the daily protein requirement for men while women require 6 to 7 ounces (Martin, S. 2011)

Minerals

Minerals are very crucial for the day to day proper functioning of the body and beef is a rich mineral source as far as body requirements are considered. It contains Iron, Zinc, Magnesium, Selenium, Copper, Phosphorous and Potassium. The Zinc and iron found in beef are more readily absorbed than those from other sources such as vegetables (Martin, S. 2011).

Vitamins

Vitamin B12, B6, Thiamin, Riboflavin and Pantothenic acid are some of the vitamins found in beef. It is important to note that most of those people who abstain from red meat and vegetarians mostly so suffer from vitamin B12 deficiency and might need to take b12 supplements.

Fats

Beef is often criticized for its high content of saturated fats. Though fats are essential in any diet, too much of the concentrated fat found in red meat is a major contributor to a host of health complications. Luckily, it is possible to get lean cuts of beef according to ones choice and taste. Some of these cuts are sirloin steaks, round roasts and steaks, chuck roasts, briskets and flank steaks which are delicious and lean. The standard is that lean beef cuts should have 10 grams or below of fat content and a 3.5 ounce serving should contain saturated fats less than 4.5 grams (“My Fitness Pal” 2012).

Micro organisms likely to survive in beef

Escherichia Coli (E. coli) 0157

These belong to the coliform family of microorganisms. Most of its strains live in the gut and help to check the growth of harmful microorganisms. The E. coli 0157:H7 strain causes a distinctive deadly disease called E. coli Hemorrhagic Colitis. The strain is more associated with ground beef.

Salmonella serovars

Salmonella is a bacteria family with more than 2300 serotypes. The bacteria, once consumed can continue living and growing inside the intestines and can cause an infection resulting in illness with the severity depending on the strain, the resistance of the host and the size of the colony. The bacteria are normally spread through contact with the contents of the entrails during processing of beef. These pathogens can be killed by high temperatures but survive refrigeration. The infection results in an infection called salmonellosis (Betts, White, & Everis, 2001).

Campylobacter jejuni

This bacterium normally survives in the intestines of healthy animals and in untreated water (mostly in surface water). Human infection mostly comes from inadequately cooked and raw foods and from un-chlorinated water. It thrives in areas of low oxygen concentration and is easily killed by heat and is inhibited by salt acid and drying. The bacteria cause an infection called campybacteriosis or campylobacter enteritis (Betts G. White, P. & Everis, L. 2001).

Listeria monocytogenes

This pathogen was previously considered a veterinary concern until the 80’s when Listeriosis was later associated with the pathogen. The pathogen survives very long under severe conditions even in sub zero temperatures. The salt and (relatively) drying resistant pathogen is communicated by humans and animals and records fatality in 20 to 25% of diagnosed cases (Hinton & Teagasc, 2000).

Staphylococcus aureus

This bacterium is normally on the skin and nose of humans and thrives much in infections like wounds, boils, pimples, acne and people with colds and sinusitis. Sewage, milk and untreated water are also rich sources. The bacteria’s association with beef is through handling and preparation. It produces an odorless and tasteless toxin that causes illness when it comes into contact with warm food. Staphylococcal intoxication results from this toxin which is seldom fatal (Hinton & Teagasc 2000).

Brochothrix thermosphacta

This is a spoilage organism whose ecological niche is meat. It is gram positive, non – spore forming, catalane – positive, non – motile anaerobic. It can grow at temperatures from 00C with low oxygen and high CO2 Concentrations. It is normally found on the surface of meat.

Carnobacterium

This is a gram positive bacterium. They adjust to environments through their ability to metabolize carbohydrates and its interaction with C. vriridans causes a green discoloration in meat.

Clostridium

These are gram positive anaerobes which produce toxins.

Pseudomonas

These are the bacteria mostly associated with beef spoilage. They are gram negative aerobic bacteria they can break down the peptides in meat and produce foul odors caused ammonia hydrogen sulfide and amines. The most common in beef is the Pseudomonas fragi (Hinton & Teagasc, 2000).

Other organisms likely to be found on beef are Rahnella aquatilis, Rahnella spp., and L. sakei

Microbial spoilage

The microbial spoilage of beef manifests itself in various ways mostly depending on the oxygen levels in the environment. The microorganisms mainly come from the skin and intestinal tract of the animals (Betts, White & Everis, 2001).

Oxygenated areas

Under these conditions, the spoilage will be from three factors namely

Aerobic bacteria: These will result in the beef getting slime on the surface become discolored and the odor will significantly change. The beef will start producing gases and the fat on the beef will start decomposing.

Yeasts: The beef will develop a slimy surface, become discolored and its taste and odor will change. The fat will also start decomposing.

Molds: Beef spoiled by mould will manifest itself by a whiskery surface that is sticky, will change in odor and colour and its fat will start to decompose.

Un-oxygenated areas

Anaerobic bacteria: The beef will become putrefied and will have a foul odor. The meat will also become sour and start emitting gas.

Beef Preservation

Apart from the normal preservation by freezing and refrigeration, beef can be preserved by;

Salt curing: This is arguably the oldest method. The meat can be brine cured; dipped in salt water, dry cured; where it is rubbed with the salt or a combination of both.

Smoking: This is exposing meat to smoke and can be done in high temperatures as well as in cold ones. The meat is first dried on the surface and salt could be added for flavor. Smoking also adds to the flavor of beef.

Drying; this is another old mode of preservation and mostly involves curing the meat before exposing it to the sun. Mostly practiced in arid areas.

Pickling; this is soaking the meat in vinegar, honey or sugar. These meats are often cooked before pickling.

Products

Beef products are many and mostly differ according to the part of the body and the mode of preparation. They include beef loin, beef forelimb, English stewing lamb, beef burgers, steak mince, topside, ox-tail etc. The Meat is first cut into primal cuts separated from the carcass. The steaks and other characterizations are then cut from the primal cut.

References

Betts, G. D., White, P., & Everis, L. (2001). Microbial spoilage: Modelling growth of meat spoilage bacteria. Chipping Campden, UK: Campden and Chorleywood Food Research Association Group.

Calories in generic Kenyan stew. Retrieved from my fitness pal website: http://www.myfitnesspal.com/food/calories/generic-kenyan-beef-stew-26631218Martin, S.(2011 September) Kenyan Nyama (Stewed Beef). Global table adventure. Retreived from: http://globaltableadventure.com/2011/09/25/recipe-kenyan-nyama-stewed-beef/Hinton, M., & Teagasc (Organization). (2000). Microbial control in the meat industry. Dublin: Teagasc, National Food Centre.

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