PREDICTING THE PHYSICOCHEMICAL PROPERTIES OF PORK BELLY AND THE EFFECT OF COOKING AND STORAGE CONDITIONS ON BACON SENSORY AND CHEMICAL CHARACTERISTICS
The first objective of this research was to use a widely varying pig population to create prediction algorithms for dual energy X-ray absorptiometry (DXA) pork carcass compositional estimate and pork belly softness measurement. Further, bellies with compositional extremes were used in bacon production and cooked in two ways to determine the impact of composition, storage days and cooking method on lipid and protein oxidation as well as heterocyclic aromatic amines. A total of 648 pigs, either barrows or gilts, from three sire breeds (Lacombe, Duroc or Iberian boar × Large White * Landrace F1 dams), were provided one of three diets (conventional, canola-based or flaxseed-based feed) ad libitum until they reached either ~120 or 140 kg slaughter weight. These variations were intentionally introduced so that the animal population could adequately represent the variation applicable to commercial production. Following slaughter, carcass sides and primal cuts were scanned under DXA equipment. For the second experiment, 198 left side bellies were assigned to belly-flop angle and subjective score measurements to evaluate pork belly softness. The third experiment employed 44 right side bellies which were randomly selected from the treatment extremes (barrows or gilts, Iberian or Lacombe, and control or flaxseed based diet). These 44 bellies were processed into bacon slices which were cooked with either microwave heating or pan frying after 2 or 28 days of refrigerated storage. Regardless of variation in animal population, DXA accurately predicted dissected/chemical fat and lean content of carcass sides and primal cuts (R² > 0.94, P < 0.01; RSD, 0.8 to 2.9%). The multifactorial nature of pork belly softness was confirmed with a stepwise regression model that explained up to 77 and 83% of subjective belly softness score and belly-flop angle measurement, respectively, with both chemical and dimensional factors as the predictors. Employing belly-flop angle measurement in the assessment of pork belly softness would require a correction for belly length. Although microwave cooking of bacon led to a significantly higher increase in protein oxidation (P < 0.001), cooking in a frying pan resulted in higher increase in heterocyclic aromatic amines and lipid oxidation in bacon (P < 0.001). Storage days and belly composition did not affect the production of these chemical compounds (P > 0.05). The cooking treatments and storage days also had minimal effects on bacon sensory attributes. Overall, the present study established mathematical models to improve DXA estimate of pork carcasses and enhance pork belly softness assessments. The results could also inform public health recommendations regarding choice of cooking method for bacon.
bacon, dual energy X-ray absorptiometry, protein oxidation, lipid oxidation, heterocyclic aromatic amines, micowave, pan-frying
Doctor of Philosophy (Ph.D.)
Food and Bioproduct Sciences