反应详情

In the second of a series of flavor stability tests, high oleic sunflower oil (abbreviated “HOSO”, see above from Cargill, Inc.), anhydrous milkfat (AMF) and a palm oil stearin+olein blend obtained from Loders Crooklan, Channahon, Ill. (SansTrans™39 product abbreviated “POSO” with a melting point of 37-41° C.), were each evaluated for their ability to stabilize the flavor of menhaden fish oil dispersed in skim milk. Skim milk was fortified with sufficient non-fat dry milk to produce a final protein level in the milk of 4.2% by weight. Menhaden fish oil that had been isolated and refined by Omega Protein, Inc. (Houston, Tex.) as well as the HOSO oil and the AMF and POSO fats were supplemented with the same antioxidant levels of mixed tocopherols, rosemary extract, ascorbyl palmitate and lecithin described above. Fish oil was diluted with either 5 parts by weight of the HOSO or 2 parts by weight of AMF or 2 parts by weight POSO. The first of these blends containing fish oil diluted with liquid HOSO (500 mg HOSO+100 mg fish oil providing 32 mg EPA+DHA per 8 fl oz serving of milk) was dispersed directly into the skim milk using high shear mixing (Turrax blender at 4000 rpm). The other two skim milk preparations required preparation of aqueous pre-emulsions in which 2 parts of the solid fats, POSO or AMF were melted and combined with 1 part of fish oil to form melted fat blends. The aqueous pre-emulsions contained 30% by weight of these melted fat blends and 70% by weight of a water phase. The water phase contained sodium caseinate adequate for stabilizing the emulsion, and the fat blends were supplemented with an adequate level of a mono- and diglyceride DATEM derivative (Panodan® S Visco-Lo 2000, a diacetyl tartaric acid ester derivative obtained from Danisco USA, New Century, Kans.) that also assisted in stabilizing the aqueous emulsions. These emulsions were added to the skim milk with medium shear agitation, in amounts sufficient for providing 32 mg EPA+DHA per 8 oz serving of milk. Milks were pasteurized at 280° F. for 3 sec, homogenized at 2000+500 PSI, and stored refrigerated at 40° F. in both 12 oz white PETE plastic bottles and also in transparent bottles. These bottles were then stored either in the dark or under cool white fluorescent lighting. Sensory testing of these milks was performed over 15 days of storage. None of the sample milks packaged in white PETE bottles developed a fishy flavor over this period regardless of exposure to light, although all samples stored in the dark were reported to have a cleaner, fresher taste. However, with milk samples stored in transparent bottles, fluorescent light exposure resulted in fishy off-flavors developing in all of the fish oil-fortified milk samples. More specifically, off-flavors were first detected on day 8 for milk containing fish oil that had been diluted 6-fold with HOSO. Subsequently, off-flavors were detected on day 11 for fish oil diluted only 3-fold with AMF, and finally on day 13 for fish oil diluted only 3-fold with POSO. Therefore, AMF and POSO fats were surprisingly more effective even when used at a lower level than HOSO oil for stabilizing fish oil against photo-oxidation by fluorescent lighting (11 and 13 days stability compared to 8 days). Taking into consideration that the fish oil was combined at twice the concentration (@ 33% by weight) with the AMF and POSO Oxidative Stabilization Fats compared to the HOSO oil (@ 17% by weight), these saturated fats are even more effective at extending shelf life (compared to HOSO) than the sensory tests indicate. These stability findings suggest that the abundance of saturated fatty acids as well as the solid nature of the AMF and POSO fat microparticles (under refrigeration) improve the stabilization of fish oil.

1. additiondispersed in skim milk
2. customto produce a final protein level in the milk of 4.2% by weight
3. customMenhaden fish oil that had been isolated
4. extractionextract
5. additionFish oil was diluted with either 5 parts by weight of the HOSO or 2 parts by weight of AMF or 2 parts by weight POSO
6. additionThe first of these blends containing fish oil
7. additiondiluted with liquid HOSO (500 mg HOSO+100 mg fish oil providing 32 mg EPA+DHA per 8 fl oz serving of milk)
8. additionwas dispersed directly into the skim milk
9. additionmixing (Turrax blender at 4000 rpm)
10. customThe other two skim milk preparations required preparation of aqueous pre-emulsions in which 2 parts of the solid fats, POSO or AMF
11. customto form
12. additionThese emulsions were added to the skim milk with medium shear agitation, in amounts sufficient
13. customfor providing 32 mg EPA+DHA per 8 oz
14. customstored refrigerated at 40° F. in both 12 oz white PETE plastic bottles and also in transparent bottles
15. temperaturein the dark or under cool white fluorescent lighting
16. waitSensory testing of these milks was performed over 15 days of storage
17. customresulted in fishy
18. waitMore specifically, off-flavors were first detected on day
19. addition8 for milk containing fish oil that
20. additionhad been diluted 6-fold with HOSO
21. waitSubsequently, off-flavors were detected on day
22. addition11 for fish oil diluted only 3-fold with AMF
23. additionfinally on day 13 for fish oil diluted only 3-fold with POSO
24. customby fluorescent lighting (11 and 13 days stability compared to 8 days)
25. concentrationthe concentration (@ 33% by weight) with the AMF and POSO Oxidative Stabilization Fats