Complexes of lutein with bovine and caprine caseins and their impact on lutein chemical stability in emulsion systems: Effect of arabinogalactan.

Lutein is an important xanthophyll carotenoid with many benefits to human health. Factors affecting the application of lutein as a functional ingredient in low-fat dairy-like beverages (pH 6.0-7.0) are not well understood. The interactions of bovine and caprine caseins with hydrophobic lutein were studied using UV/visible spectroscopy as well as fluorescence. Our studies confirmed that the aqueous solubility of lutein is improved after binding with bovine and caprine caseins. The rates of lutein solubilization by the binding to bovine and caprine caseins were as follows: caprine αS1-II-casein 34%, caprine αS1-I-casein 10%, and bovine casein 7% at 100 µM lutein. Fluorescence of the protein was quenched on binding supporting complex formation. The fluorescence experiments showed that the binding involves tryptophan residues and some nonspecific interactions. Scatchard plots of lutein binding to the caseins demonstrated competitive binding between the caseins and their sites of interaction with lutein. Competition experiments suggest that caprine αS1-II casein will bind a larger number of lutein molecules with higher affinity than other caseins. The chemical stability of lutein was largely dependent on casein type and significant increases occurred in the chemical stability of lutein with the following pattern: caprine αS1-II-casein > caprine αS1-I-casein > bovine casein. Addition of arabinogalactan to lutein-enriched emulsions increases the chemical stability of lutein-casein complexes during storage under accelerated photo-oxidation conditions at 25°C. Therefore, caprine αS1-II-casein alone and in combination with arabinogalactan can have important applications in the beverage industry as carrier of this xanthophyll carotenoid (lutein).

Qualitative effects of fresh and dried plum ingredients on vacuum-packaged, sliced hams.

Boneless ham muscles (Semimembranosus+Adductor) were injected (20% w/w) with a curing brine containing no plum ingredient (control), fresh plum juice concentrate (FP), dried plum juice concentrate (DP), or spray dried plum powder (PP) at 2.5% or 5%. Hams were cooked, vacuum-packaged, stored at<4°C and evaluated at 2-week intervals over 10 week. Evaluations were performed on sliced product to determine cook loss, vacuum-package purge, Allo-Kramer shear force, 2-thiobarbituric acid-reactive substances (TBARS), proximate analysis, objective color, sensory panel color and sensory attributes. FP, DP and 2.5% PP increased (P<0.05) cook loss by 2% to 7% depending on treatment and level, but the highest cook loss (17.7%) was observed in hams with 5% PP. Shear force values increased as the level of plum ingredient increased (P<0.05) from 2.5% to 5%, and the highest shear values were observed in hams containing 5% FP. There were no differences (P>0.05) in lipid oxidation among treatments as determined by TBARS and sensory evaluation. FP and PP ham color was similar to the control, but DP had a more intense atypical color of cured ham. Minimal changes in physical, chemical and sensory properties were observed during storage of all treatments.

Antioxidant properties of dried plum ingredients in raw and precooked pork sausage.

Raw pork sausages with no antioxidant (control), 3% or 6% dried plum puree (DP), 3% or 6% dried plum and apple puree (DPA), or 0.02% butylated hydroxytoluene and butylated hydroxyanisole (BHA/BHT) were (1) stored raw in chubs at 4 degrees C (RR) and evaluated weekly over 28 d, (2) cooked as patties, vacuum packaged, and stored at 4 degrees C (PR) for weekly evaluation over 28 d, or (3) cooked, vacuum packaged, and stored at -20 degrees C (PF) and evaluated monthly over 90 d. DP at 3% or 6% levels was as effective as BHA/BHT for retarding lipid oxidation in PR sausage patties. Likewise, DP at 3% was equally as effective in PF patties, but DP at 6% was even more effective (lower TBARS values) than BHA/BHT for retarding oxidative rancidity. All treatments decreased the fat and increased moisture content of raw sausages but only 6% DP reduced cooking yields. Inclusion of 6% DP decreased internal redness while both 6% DP and DPA increased yellowness of raw sausage. Trained panel sensory evaluations indicated that DP enhanced sweet taste, decreased salt and bitter tastes, and masked cooked pork/brothy, cooked pork fat, spicy/peppery, and sage flavors. In general, warmed-over flavor notes were not affected by storage treatments. Overall, pork sausage with 3% DP or DPA was as acceptable to consumers as the control or those patties with BHA/BHT, but patties with 6% of either plum product were less desirable. Inclusion of 3% DP was effective as a natural antioxidant for suppressing lipid oxidation in precooked pork sausage patties.

Antioxidant properties of plum concentrates and powder in precooked roast beef to reduce lipid oxidation.

Boneless beef roasts (Semimembranosus+Adductor) were injected (20%) with a brine containing (1) no plum ingredient (control), (2) 2.5 or 5% fresh plum juice concentrate (FP), (3) 2.5 or 5% dried plum juice concentrate (DP), or (4) 2.5 or 5% spray dried plum powder (PP). Whole roasts were cooked, vacuum-packaged and stored at <4.0°C for 10wk. At 2wk intervals, evaluations were performed on sliced product to determine vacuum-packaged purge, Allo-Kramer shear force, lipid oxidation (TBARS), color space values, and sensory attributes. All plum ingredients reduced TBARS values and had minimal effects on tenderness, sensory characteristics, color and appearance. Small changes in purge, color values, TBARS and some sensory properties were found during storage. These results indicate that 2.5% FP or DP could be incorporated into precooked beef roasts to reduce lipid oxidation and potentially, warmed-over flavor (WOF).