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Document Type

Thesis - University Access Only

Award Date

2010

Degree Name

Master of Science (MS)

Department

Dairy Science

First Advisor

Robert J. Baer

Abstract

Ice cream quality is dependent on many factors including the storage temperature. Currently, the industry standard for ice cream storage is -28.9°C (-20°F). Ice cream production costs may be decreased by increasing the temperature of the storage freezer, thus lowering energy costs. The first objective of this research was to evaluate the effect of four storage temperatures on storage quality of commercial vanilla flavored light (LT} ice cream and full fat (FF) ice cream. Storage temperatures used were -45.6°C (-50°F), -26.1 °C (-15°F), and -23.3°C (-10°F) for the three treatments and -28.9°C (-20°F) as the control or industry standard. As expected, LT ice cream mix had a lower (P < 0.05) percentage of fat and total solids compared to the FF ice cream mix. Light ice cream mix was higher (P < 0.05) in protein, ash, and pH than FF ice cream mix. Titratable acidity percentage and freezing point for LT and FF ice creams were similar (P > 0.05). Ice crystal sizes were analyzed by a cold-stage microscope and image analysis at 1, 19.5, and 39 weeks (wk) of storage. The lowest storage temperature, -45.6°C, was tested to indicate whether the industry standard was the optimal storage temperature for LT and FF ice creams. There was no difference (P > 0.05) in ice crystal size between the storage temperatures of LT and FF ice creams at-19.5 or 39 wks. However, there was an increase (P < 0.05) in ice crystal sizes between 19.5 and 39 wk storage times. An experienced sensory panel evaluated the coldness intensity, iciness, creaminess, overall body/texture acceptance, storage/stale off-flavor, and overall flavor acceptance of the LT and FF ice creams at 39 wk of storage. Sensory evaluation indicated that there was no difference (P > 0.05) between the different storage temperatures for LT and FF ice creams. Flavor and body/texture scores of the sensory evaluation were affected (P < 0.05) by the type of mix, panelist perception, and storage temperature (P < 0.01). In a second study, LT and FF ice creams were heat shocked (HS) by storing at -28.9°C (-20°F) for 35 wk and then alternated between -23.3°C (-10°F) and -12.2°C (10°F) every 24 hours. Heat shocked ice creams were analyzed at 2 and 4 wk of storage for ice crystal sizes and evaluated by the experienced sensory panel. Although there was a difference (P < 0.05) in ice crystal sizes for LT and FF ice creams during the HS storage, sensory results indicated there was no difference (P > 0.05): Storing LT or FF vanilla flavored ice creams at the storage temperatures within this research did not affect quality of the ice cream. Therefore, ice cream manufacturers could conserve energy by increasing the temperature of freezers from -28.9°C to -26.1 °C. Freezers will naturally fluctuate from the set temperature; therefore using -26.1 °C allows for a safety factor, even though -23.3°C temperature also did not affect ice cream quality.

Library of Congress Subject Headings

Ice cream. ices. etc
Cold storage
Food -- Quality

Description

Includes bibliographical references (pages 34-38)

Format

application/pdf

Number of Pages

66

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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