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Two studies were conducted to determine if sous vide was a viable way to improve palatability of various beef cuts, and to determine whether extended aging duration and the presence of a bone impacts the consumer ratings of beef short loins.When evaluating the impact of sous vide cooking (SVG) on multiple beef muscles, there was a muscle × method interaction for overall liking (P = 0.04). The traditionally cooked (TRAD) Longisimus lumborum (LL) was rated the highest (P < 0.05). The Chuckeye steak (CHE) was rated next, both TRAD and SVG, with the traditional ranked higher, this was followed by the Triceps brachii (TB) also for both TRAD and SVG, however for the TB the SVG ranked higher (P < 0.05). The TRAD Biceps femoris (BF) rated the lowest (P < 0.05) of all of the muscles. Shear force did no differ between the cooking treatments (P > 0.05), or was there an interaction between muscle × method for shear force measurements (P < 0.05). The LL was rated the highest for tenderness (P < 0.05) while the BF was rated the lowest (P < 0.05). The second study compared subprimals aged over three aging periods (21, 42 63 days), then split into bone-in or boneless steaks, there were no interactions observed within the consumer data (P ≥ 0.05). BI steaks were rated higher (P < 0.05) for juiciness and overall liking by consumers, however BI and BL were rated similarly by consumers for tenderness and flavor (P > 0.05). When evaluated by consumers, aging did not have an effect on tenderness (P ≥ 0.392), juiciness (P ≥ 0.890), flavor (P ≥ 0.901) or overall liking (P ≥ 0.518). A greater percentage of BI steaks (P0.05). Bone-in steaks had higher WBSF values than BL steaks (P < 0.05). As aging time increased, WBSF values decreased (P 0.05). Cooking method had a large impact on consumer ratings. Traditionally cooked steaks had higher ratings by consumers than sous vide steaks. Steaks from muscles used commonly by consumers had higher consumer ratings. Consumers found no differences between the different aging periods for tenderness, however as aging time increased, WBSF decreased as well, showing that extended aging may require further research to determine its viability. The implications of this study are that BI product shows promise with greater juiciness and overall liking. Sous vide is still a valuable tool. It’s capable of cooking steaks consistently and with no ill effects on the quality of the steaks.

Abstract: Non-enzymatic browning reactions represent a complex phenomenon occurring during thermal processing of food, and are categorised as either the Maillard reaction or caramelization. Besides temperature, these reactions depend upon water activity (aw), pH and the concentration of reactants. Non-enzymatic browning reactions give flavour and colour to foods, and are central in the production of caramel colours. On the other hand, these reactions also produce potential toxic compounds such as 4-methylimidazole (4-MEI), 5-hydroxymethylfurfural (5-HMF) and 2-acetyl-5-tetrahydroxybutyl imidazole (THI) which increase with temperature and are defined as neo-formed contaminants in caramel. Glucosamine (GlcN) is an aminosugar capable of eliciting non-enzymatic browning reactions even at 25-37°C. The structure of GlcN is peculiar as it contains both an amino group and a carbonyl group in the same compound; this makes it an unstable molecule capable of forming degradative and self-condensation reactions generating plethora of compounds. One compound generated by the non-enzymatic browning of GlcN is diacetyl, and is known for its appealing butter-like aroma. Other compounds are fructosazine (FR) and deoxyfructosazine (DOFR), and are known for anti-diabetic and anti-inflammatory properties, and glyoxal, methylglyoxal, diacetyl and 3-deoxyglucosone for antimicrobial properties. Thus, GlcN can be used to produce a caramel containing interesting functional compounds with aromatic, antimicrobial and anti-inflammatory properties even at moderate temperatures. Hence, one of the main objectives of this thesis was to produce safe and flavourful GlcN-derived caramel under vacuum conditions (“sous-vide”) or by combining with specific amino acids. The first study was designed to study the sous-vide non-enzymatic browning of GlcN at 50, 60 and 70°C for 12 h. The physico-chemical properties, quantification of α-DCs, polyhydroxylalkyl pyrazines (FR and DOFR), alkylimidazoles (4-MEI and THI) and 5-HMF were determined in the sous-vide GlcN caramels as compared to GlcN caramels generated under the normal, ambient oxidative conditions. The results revealed that caramelization under vacuum generated significantly lower (p < 0.05) diacetyl concentrations compared to oxidative conditions at all incubation temperatures. Significantly greater concentrations of FR were found in the vacuum treatments. THI and 5-HMF concentrations in all caramels studied were well below the toxicity levels, while the potentially more toxic 4-MEI was not detected in any of the caramels produced. This study shows that sous-vide conditions did not improve the formation of butterscotch flavour but increased the amount of the biologically active polyhydroxylalkyl pyrazines. The second study focused on investigating the effect of different amino acids on non-enzymatic browning of GlcN incubated at 70°C for 12 h. The resulting GlcN-amino acid “caramels” were analyzed for α-DCs, polyhydroxyalkyl pyrazines, heterocyclic compound and alkylimidazoles. The greatest (p < 0.05) amount of butterscotch aromatic compound diacetyl, and FR and DOFR were generated in GlcN-glycine caramels. GlcN-arginine caramels generated the greatest (p < 0.05) amount of HMF. The neo-formed contaminants alkylimidazoles (4-MEI and THI) were not present in any of the GlcN-amino acid caramels. The THI was present in the GlcN control, suggesting that the addition of the amino acids completely inhibited the formation of these contaminants. Principal component analysis categorised the majority of the GlcN-amino acid combinations where GlcN-glycine and GlcN-serine were the best discriminated. In general, the addition of glycine to GlcN non-enzymatic browning produces a “caramel” solution with the greatest concentration of flavourful compounds. Overall, this thesis demonstrated that different types of caramels produced depend on the presence or absence of vacuum, as well as the type of amino acids added during the non-enzymatic browning reaction of GlcN. These caramels have the potential to be used in different food applications such as simple colourants, as aromatic caramels, or even conferring beneficial health activities.