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M. NONNEMACHER and L. Meunier-Goddik. Dept. of Food Science & Nutrition, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331-6602 Process parameter fluctuations are common during commercial whey processing, specifically during the crystallization step. These fluctuations occur in the pH of whey, crystallization temperature, and length of time of crystallization. However, there is little information known about whether these fluctuations have an effect on lactose crystallization and whey powder quality. The objective of this study was to determine the effects of whey concentrate crystallization parameters (pH, temperature, length of time of crystallization) on lactose crystal forms and amount of lactose crystallized. Effects on freeze-dried powder quality parameters, hygroscopicity, and flowability, were also investigated. Whey concentrate was obtained from a local processor and crystallized under various conditions. Control conditions were pH 5.5 with incubation at 10 °C for 12 hr. Parameters chosen are similar to extremes generally seen in commercial processing. Treatments of pH (4.5, 6.5), temperature (5 °C, 15 °C), length of crystallization (9 hr, 15 hr), and no seeding material were applied separately. Upon completion of crystallization, samples were freeze-dried and then analyzed for lactose crystal forms using x-ray crystal diffraction. Hygroscopicity and flowability were also measured. X-ray crystal diffraction patterns indicated that lactose only crystallized in the alpha-lactose monohydrate (ALM) form in measurable amounts. No significant differences in lactose forms or amount crystallized were observed for any of the treatments. Quantification using peak areas indicated that 55% of the lactose was present as ALM crystalline form. Significant differences in hygroscopicity were observed, but no significant differences in flowability were measured. The results suggest that normal fluctuations in whey processing during the crystallization step have an effect on the quality parameter of hygroscopicity even though there is no significant effect on the amount or forms of crystalline lactose.
Session 31, Dairy Foods: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |