Nutrient content of South African C2 beef offal
Salomina M. van Heerden • Liesl Morey
Received: 20 November 2013 / Accepted: 2 July 2014 / Published online: 29 July 2014
_ Springer Science+Business Media New York 2014
Abstract The aim of this study was to determine a selected group of nutrients in raw and cooked C-age, fat
code 2, bovine offal and to evaluate it as a potential sourceof nutrients such as protein and iron. Samples of the different raw and cooked C-age, fat code 2 bovine offal parts were analysed by accredited laboratories. Cooking affected mainly the nutrients such as moisture, protein, fat, ash and energy as well as the micronutrient values, which were higher in the cooked offal cuts. Some cuts of offal (heart,lungs and spleen) are as lean as or leaner than chicken meat. The biggest difference could be attributed to the difference in fat content between the cuts, for example, the tongue is very high in fat with 23.30 g/100 g and therefore has the highest kJ (1,157 kJ) content of the six cuts of offal. The spleen had the highest iron content of 36.6 mg/100 g.
Significantly lower fat contents were observed in the lungs (2.53 g/100 g), heart (6.7 g/100 g) and the spleen (3.20 g/100 g) cuts when compare to the values in the 1999 version of the South African Medical Research Council’s Food Composition Tables. The heart, intestine and spleen are also an important source of iron and compare favourable to beef. The heart also contained the highest zinc content of all the cuts. Offal containing primary food components which have high potential in human nutrition such as high protein content and can therefore is recommended as a good low cost nutritious product.
Introduction
Scientific literature on the nutrient content and food composition tables of offal is relatively scarce. However the nutritive value of all food products including meat and meat products is important, in view of theconsumer
interest and demand for a healthier lifestyle [1]. Therefore,there is a great need for more detailed information on food with adequate nutritive value, especially protein, for the informal and poorer sections of the population in South Africa. With the WHO’s estimation that 5 million people are dying every year from starvation, more attention should be given to the possibility of using proteins such as offal (beef, sheep), as protein sources in the diet [2]. Offal, or organ meats, refers to the internal organs and entrails of a butchered animal, makes up a substantial portion of an animal’s meat weight. The word does not refer to a particular list of edible organs, but includes most internal organs other than muscle and bone [3]. It is also described
as those parts of a meat from a carcass which are used as food but which are not skeletal muscle. It covers insides including the heart, liver, and lungs (collectively known as the pluck), all abdominal organs and extremities: tails, feet,and head including brains and tongue. In the USA theexpressions ‘‘organ meats’’ or ‘‘variety meats’’ are used instead [4]. In South Africa offal is mostly enjoyed by South Africans of diverse backgrounds. Due to the popularity of this dish, it is one of the few customs that white (especially Afrikaners) and black South Africans share. Offal dishes inSouth Africa include stomach, hooves, shin, intestines,
liver, head, tongue and very rarely in certain communities,testicles, and are consumed ‘fresh’ (i.e. not frozen).
Feeding the expanding population of the world is a major challenge facing food scientists with protein malnutrition
that remains an unsolved problem for developing countries [5]. There are also the harsh economic times to consider.
More and more consumers are turning to the less expensive cuts and items on the butcher’s shelves such as offal.
To obtain the highest margins for edible offal it is important to understand the culture and need of the target market. In South Africa for example there is a large domestic market for offal. Offal represents high value cheap protein as in most developing countries with a very poor population and offal is a staple to many diets [6]. Offal cuts such as liver, spleen, lung, heart and kidney are good sources of protein,and notably very valuable for its nutrition. In most parts of the world, especially the less developed countries, it is valued accordingly [4]. Bovine spleen is a rich source of iron while liver is rich in vitamin A. As offal does not keep well, it must either be preparedand cooked quite soon after slaughter or turned into a product. Sensory acceptability is an important factor in the utilization of offal (meat by-products) for human consumption. Liver has an appealing taste and is used in the industrial manufacture of sausage and other processed meat products. Spleen and lung are edible but not highly acceptable for everyone although spleen is used in some traditional cooked sausages [5]. Proteins act as emulsifiers in processed meat products by lowering the interfacial tension between water and oil. During the development of the uncooked (raw) controlsausages and meat sausages containing beef offal (formulations1–4) in a study done by Magoro [7], meat sausages were found to be good sources of protein, vitamins B3 (niacin), B6 (pyridoxine) and B12(cyanocobalamin) andminerals (magnesium, phosphorus, iron and selenium).High vitamin B12 content was observed in all four sausages (see highlighted values on Table 1 below) [7]. Apart from being an excellent source of protein, meat products are also good sources of B-complex vitamins, dietary phosphorus and iron. They are low in calcium, but contribute a significant percentage of other minerals such as copper, zinc, sodium, potassium and magnesium [1]. According to Anderson [8] the vitamin content of meat byproducts such as liver, kidney and heart is usually higher than that of the lean tissue and the riboflavin content of kidneys and liver also exceeds that of lean beef tissue. Organ meats are rich in fat and/or cholesterol content [9]. Cholesterol content becomes more concentrated during cooking due to the decrease in tissue weight [9]. A recent study [10] indicated that South African beef offal contains more moisture and lower levels of fat and cholesterol, iron and zinc to mention but a few when compared to other sources of data (Table 2). These values differ from current data in the condensed
food composition tables for South Africa [11] and the British food composition tables [12]. This is a concern as
offal is consumed by a large part of the population. The aim of this study was to determine a selected group of
nutrients in C-age, fat code 2 (C2) bovine offal and to evaluate it as a potential source of protein and iron.
With the correct sampling, analysis and interpretation of the composition of South African beef offal (red offal =
tongue, lungs, liver, heart, spleen, kidneys and whiteoffal = stomachs, small intestine), the nutrient content and
quality characteristics of South African beef offal can effectively be compared to a recent study [10]. When the
correct data on the nutrient content of South African beef offal is incorporated into the food composition tables of the Medical Research Council (MRC), the data will serve as a reliable standard of reference for the health professionals and the food industry to serve the poorer communities A double burden of nutrition related diseases is prevalent in many households and communities in South
Africa, as both over and under nutrition occur due to rapid urbanization and acculturation. The outcome of the
study will possibly help to act as a reference for health professionals, industry and ultimately consumers to
improve nutritional well-being towards a healthy lifestyle.
Materials and methods
Sampling Six
C2 cattle (three for raw analysis and three for cookedanalysis) were slaughtered at the abattoir of the Agricultural
Research Council-Animal Production Institute (Irene campus) as part of a research project. The fresh red beef
offal [lungs, heart, spleen, kidney, tongue, liver and the rough offal consisting of the tripe (stomachs) and small
intestines] were sampled after a full health inspection was done on the slaughtered carcasses. For this project the
‘‘Red offal’’ means the lungs, heart, liver, spleen, tongue. ‘‘Rough offal’’ means the stomachs, intestines, [13].
Inspection of raw materials
Both red and rough beef offal sets were inspected for signs of various diseases immediately after slaughter.
Sets of red beef offal such as hearts and lungs were inspected for the presence/absence of abscesses by
the ARC-Irene’s abattoir meat inspector. Beef spleens were inspected for anthrax and livers for Fasciola Hepatica,
other parasitic worms and abscesses. The stomachs were inspected for abscesses and the intestines for worms and
abscesses. After inspection by the health inspector, the beef offal cuts were processed as follows: Lungs The trachea was removed Heart The full heart was removed from the pericardium and the arteries and veins trimmed from the base of the heart Spleen The spleen was prepared by the removal of the splenic blood vessel Kidneys The blood vessels were removed at the ureter at their points of entry. The kidney capsule was removed and the fat in the renal hilus partially removed Tongue Was trimmed by removal of fat from the ventral surface of the tongue and the tip of the epiglottis Stomachs and intestine were handled as one cut.