E.C. Webb

The impact of animal source food products on human nutrition and health

Throughout the ages the quest for food and drink has influenced humanity’s economic, social and political development, and played a role in the organization of society and history. Nutrition (or what we choose to consume) influences the health of human beings and therefore their quality of life. Animal source foods are often the dietary component that evokes the widest array of complex scientific, economic, environmental and political issues. It is viewed as the most expensive component of any diet, yet can make significant contributions to human health through providing high quantities of essential nutrients. In addition to quantity, the high quality of the nutrients in animal source foods is important as high-quality nutrients are more readily absorbed into the human body than lower-quality nutrients from other food and non-food sources. As South Africans increasingly suffer the consequences of inappropriate diets (overand undernutrition), the role of animal source foods as part of a healthy diet requires continuous investment in research and extrapolation of information towards appropriate guidelines and recommendations. Although it is often suggested that the intake of animal source foods should be limited because of possible linkages between animal product consumption and health, scientific evidence increasingly indicates the beneficial role that animal source foods can play in preventing and combating obesity and certain non-communicable diseases related to over-nutrition. This article aims to describe the nutritional role of animal source foods as part of a healthy South African diet and presents a review of recent findings related to their nutrient contribution, as well as evidence relating to common health concerns. ________________________________________________________________________________

The beef tenderness model

In Phase1 of this study, three breed types (Simmentaler-, Brahman- and Nguni bulls; n = 60 each) were grain-fed and slaughtered at 12 months of age (A-age, fat-class 2). Feed was withdrawn for either three hours or 24 hours pre-slaughter. Within each feed withdrawal group, three electrical stimulation (ES) treatments were applied, viz. ES for 15 seconds, 120 seconds or no stimulation. In Phase 2, the effects of animal age and feeding regime were investigated using of A-age (feedlot and pasture), AB-age (feedlot and pasture) and B-age (pasture) animals. All carcasses were electrically stimulated for 15 seconds. Longer feed withdrawal increased dark-firm-dry (DFD) meat occurrence (pHu >6) in the Nguni and Simmentalercross. Brahman-cross longissimus (LL) tended to be more tender with paler colour and higher drip loss when 120 ES was applied. Longer feed withdrawal recorded higher Warner Bratzler shear force (WBSF) than three hour feed withdrawal. However, ES neutralized the effect of stress on tenderness. On average the AB-age feedlot animals produced the most tender LL followed by the B-age pasture and A-age feedlot which was similar to the AB-age pasture. A-age pasture animals produced the least tender LL steaks. The calpain proteolytic system played a pivotal role in determining the ultimate meat tenderness and although connective tissue becomes less soluble in older animals it did not play the determinant role in tenderness in this study. The intramuscular fat (< 3%) played an important role in the tenderness outcome of Nguni LL which marbled well at AB-age.