A study was conducted to investigate the effect ofspray drying on concentration of sulfamethazine (SMZ) in fluid milk dried to powder «10% moisture). Antibiotic-free skim and whole (homogenized) milk were spiked at 5, 10, 50 and 100 ppb sulfamethazine levels, pasteurized and stored at 4°C till further processed. All samples were spray dried at an inlet temperature of 180 ± 2°C and outlet temperature of 100 ± 2°C and stored at -20°C until analyzed.
Sulfamethazine concentration was determined quantitatively by HPLC, a microbial receptor assay (Charm-II®) and an ELISA assay (LacTek®) and qualitatively by an ELISA method (Cite®) in milk samples before and after spray drying. Dry milk samples were reconstituted (10% w/w) for all analyses. statistical determination of significant differences (p = 0.05) between fluid and dry milk samples and whole and skim milk sample~was completed by paired t-tests. Sulfamethazine concentrations increased 81.4% and 84.1% in skim and whole milk respectively at 100 ppb spiked level but were lower than expected increase of 88-91% based on their total solids for whole and skim milk as obtained by modified FDA HPLC method. At lower levels of 5 and 10 ppb, the HPLC method was not sensitive enough to provide usable data. Increase in sulfamethazine concentration from fluid to dry milk was also determined by· Charm-II® and LacTek® techniques. Poor recoveries and variability in data were evident due to binding of sulfamethazine to undetermined milk components as a result of processing and storage also due to break-down of sulfamethazine (mp = 176°C) at 1S00C during spray drying. Sulfamethazine 163 ppb by LacTek® and 94.6 ppb by Charm-II® (at a spiked level of 10 ppb fluid milk) was successfully removed from dried milk after 120 min using supercritical CO₂ (pressure = 5500 psi, 50 0 C / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/45244 |
| Date | 22 October 2009 |
| Creators | Malik, Shahana |
| Contributors | Food Science and Technology, Duncan, Susan E., Bishop, J. Russell, Taylor, Larry T. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | ix, 68 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 25070356, LD5655.V855_1991.M3585.pdf |
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