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Microbial degradation of FD&C Red No. 40 in strawberry-flavored milk.

C. Rush

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06-22-2020

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Abstract:

M48
Microbial degradation of FD&C Red No. 40 in strawberry-flavored milk.
C. Rush*, J. Waite-Cusic. Oregon State University Corvallis, OR.

Most high-temperature short-time (HTST) fluid milk processors declare their products are consumable 3 to 5 d after code date with minimal changes occurring in flavor and color. Flavored milks tend to display more significant quality defects near the end of shelf life which can negatively impact future purchase decisions. Most strawberry milk products include color additives, including FD&C Red No. 40 and/or red beet juice concentrate. The objective of this study was to observe the color degradation over shelf life in HTST strawberry-flavored milks dyed with FD&C Red No. 40 and to investigate a microbial cause for the color loss. Commercially available strawberry-flavored milks with FD&C Red No. 40 listed as a colorant (n = 2 brands, 3 separate lots) were obtained from local markets. At the code date, the milk was aseptically aliquoted into 50-mL conical tubes and stored at 7�C. Samples were analyzed daily for changes in pH, color, texture, and organoleptic properties (aroma). Once a defect was detected, the sample was spread plated on tryptic soy agar (TSA) and strawberry milk agar (standard methods agar with 10% vol/vol strawberry milk). Visual color degradation began one day post code date (2—4 log cfu/mL) displayed via white streaks on the surface of the sample. Seven days post code date (4—6 log cfu/mL) the samples with only FD&C Red No. 40 as the color agent were visually absent of the pink color (vibrant pink to opaque white) and samples with a secondary color agent had considerably reduced in color (vibrant pink to very light pink). Colonies were streaked on strawberry milk agar that contained FD&C Red No. 40 to select the color-degrading isolates. These isolates will undergo further sequencing to identify the species responsible for the degradation of FD&C Red No. 40 in strawberry-flavored milk.

Keywords: strawberry milk, FD&C Red No. 40, shelf-life.

Biography: Casey grew up on a farm in Silverton, Oregon. She attended Oregon State University for her B.S. in Food Science and Technology where she discovered her passion for dairy science through various undergraduate research projects. After graduating in March 2019, Casey began her M.S. in Food Science focusing on quality implications of reworked milk and dairy powders under Dr. Joy Waite-Cusic and Dr. Lisbeth Goddik. In her free time, Casey loves to ride her horse, bake delicious treats, and volunteer as a high school equestrian drill team coach.