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Summary Low- (5%) and high-fat (20%) chicken and turkey hotdogs were formulated in three groups: no antimicrobials (control), chemical preservatives (potassium lactate and sodium diacetate) alone and partial replacement of chemical preservatives by green tea (GTE) and grape seed extracts (GSE), surface inoculated (c. 103 CFU g−1) with Listeria monocytogenes, treated with or without heat treatment (65 °C for 104 s) to determine the growth of L. monocytogenes until spoilage (28 days). Maximum growth inhibitions (c. 2.0 CFU g−1) were observed in the treatments having chemical preservatives and plant extracts regardless of the meat and fat type. Furthermore, plant extracts along with chemical preservatives demonstrated additional inhibitory effect on the growth of L. monocytogenes survivors in chicken hotdog samples followed by postpackaging heat treatment. Results demonstrated that natural GTE and GSE can partially replace the chemical preservatives and further enhance the antilisterial activities when combined with heat treatment.

Effect of potassium lactate (PL) and sodium diacetate (SD) combinations at varying levels were evaluated in low (5%) and high (20%) fat chicken and turkey hotdog model systems. All the samples were surface inoculated with Lis- teria monocytogenes (approximately 4.6 log cfu/g), vacuum packed and stored at 4 o C for 28 days to determine the effec- tive combination of PL and SD and the effect of fat content on the growth inhibition of L. monocytogenes. In chicken hot- dog samples, maximum growth inhibitions (3.4 log cfu/g) were observed in low fat samples formulated with 3.0% PL and 0.15% SD. In turkey hotdog samples, maximum growth inhibitions (3.3 log cfu/g) were observed in low fat samples for- mulated with 3.0% PL and 0.2% SD. Effective combination levels determined in low and high fat chicken were 3.0% PL and 0.15% SD, whereas in low and high fat turkey, the effective levels were 3.0% PL and 0.20% SD. Overall, fat content had significant effect (P < 0.05) on growth inhibition as indicated by higher inhibitions in low fat chicken and turkey hot- dogs than high fat samples. These results demonstrate that commercial usage levels of PL (2.0%) and SD (0.15%) alone are not sufficient to control L. monocytogenes in case of pathogen contamination.

The purpose of this study was to investigate the nutrient and phytochemical composition of bitter melon leaves under varying maturity levels and drying techniques. Fresh, oven-dried, and freeze-dried leaves were evaluated over 3 maturity stages. In fresh leaves at various stages, crude fat, crude protein, and soluble dietary fiber contents ranged from 4.2% to 13.6%, 6.4% to 23.1%, and 0.04% to 3.50% on dry-weight basis, respectively. The contents of K, Ca, Mg, Fe, and Zn ranged from 1850.8 to 2811.8, 837.4 to 4978.2, 317.3 to 512.4, 8.4 to 16.7, and 4.1 to 5.9 mg/100 g dry-weight basis, respectively. Vitamin C, beta-carotene, and lutein contents ranged from 397.4 to 1275.1, 154.2 to 422.8, and 737.6 to 1304.6 microg/g dry-weight basis. The major flavonoids and phenolic acids were rutin, gentistic acid, and o-coumaric acid, which ranged from 7.57 to 12.75, 2.53 to 10.11, and 4.24 to 9.75 mg/g dry-weight basis, respectively. In oven-dried samples, 40.2% to 52.3% of vitamin C, 35.4% to 55.4% of beta-carotene, 25.6% to 71.6% of lutein, 26.4% to 84.0% of rutin, trace to 11.4% of gentistic acid, and 7.4% to 46.6% of o-coumaric acid were retained, while the retainment ratios of these components in freeze-dried samples were 84.7% to 99.0%, 76.4% to 99.3%, 90.4% to 96.1%, 39.8% to 99.3%, 24.1% to 68.4%, and 75.8% to 87.0%, respectively. The data showed that freeze-drying better preserves the nutrient and phytochemical quality of bitter melon leaves in comparison to oven-drying. Bitter melon leaf is a rich source of selected nutrients and phytochemicals.