New Model Gel System for Studying Water Activity of Foods

Biquet, B.; Labuza, Ted P

doi:10.1111/j.1745-4549.1988.tb00074.x

Cited by 16 publications

(4 citation statements)

References 24 publications

(10 reference statements)

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“…Moisture content was below 1% until RH exceeded 45%, at which point it then increased quickly to 2.2% at RH above 60%. The result was similar to values obtained previously with well-tempered chocolate [13,14]. Thus, the moisture uptake was not affected by the chocolate structure or type; the disorganized structure of untempered chocolate or the tight structure of well-tempered chocolate apparently have similar sorption behavior.…”

Section: Sorption Isothermssupporting

confidence: 89%

Surface bloom on improperly tempered chocolate

Lonchampt

Hartel

2006

Euro J Lipid Sci & Tech

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Surface bloom on improperly tempered chocolateThe surface composition, in terms of sugar and fat content, on untempered and overtempered chocolates was estimated by carefully scraping the surface layer and analyzing fat and sugar melting enthalpies by differential scanning calorimetry. The dull surface of over-tempered chocolate had a fat and sugar composition similar to the initial chocolate mass, whereas the surface bloom formed on untempered chocolate was nearly depleted of fat, containing primarily sugar and cocoa solids. This was confirmed qualitatively by using polarized light microscopy, where no fat crystals could be observed in the bloom spots. Bloom on untempered chocolate corresponded to a phase separation between fat, sugar and cocoa solids. In contrast, the grey, dull aspect of the surface of over-tempered chocolate had essentially the same sugar-tofat ratio as the intact chocolate and was due to a diffuse reflection of light on a rough surface, most likely induced by large cocoa butter crystals. Bloom on untempered chocolate developed regardless of the relative humidity of storage (between 0 and 75%). However, bloom developed more quickly and to a greater extent at lower relative humidity. Whiteness was directly related to the number, diameter and growth speed of the white bloom spots.

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Section: Sorption Isothermssupporting

confidence: 89%

Surface bloom on improperly tempered chocolate

Lonchampt

Hartel

2006

Euro J Lipid Sci & Tech

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“…The model system was based on that of Biquet and Labuza (1988). It consisted of 16g purified agar (Difco Laboratories, Detroit, MI), 52.9g microcrystalline cellulose (FMC Corporation, Philadelphia, PA), O.lM phosphate buffer (Fisher Scientific, Fair Lawn, NJ), 1000 ppm aspartame on a dry-weight basis (NutraSweet Company, Mt.…”

Section: Model Systemsmentioning

confidence: 99%

Aspartame Degradation Kinetics as Affected by pH in Intermediate and Low Moisture Food Systems

Bell

Labuza

1991

Journal of Food Science

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Kinetics of aspartame degradation in low to intermediate moisture systems were evaluated by incorporating aspartame into agar/microcrystalline cellulose model systems. They were prepared at pH 3, 5, and 7, equilibrated after freeze-drying to three water activities (0.34, 0.56, and 0.66), and stored at 2.5 to 45°C. Aspartame in such systems was most stable at pH 5 and became less stable as pH decreased or increased. As the molar buffer salt concentration increased, the rate of aspartame degradation increased. The activation energy ranged from 23 to 36 kcalhole.

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“…The model system consisted of freezedried agar/microcrystalline cellulose gels prepared by the method of Biquet and Labuza (1988) as modified by Bell and Labuza (199la). Prior to freeze-drying, 0.1 mold phosphate buffer (Fisher Scientific, Fair Lawn, NJ) was incorporated into the gel to yield wet pH values between 2.65 and 7.0.…”

Section: Model Systemmentioning

confidence: 99%

EVALUATION and COMPARISON of SIMPLE METHODS FOR pH MEASUREMENT of REDUCED-MOISTURE SOLID SYSTEMS

Bell

Labuza

1992

J Food Processing Preservation

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It is desirable to quickly and accurately determine the pH of reduced‐moisture solid food systems. Several techniques of pH determination were evaluated on such systems. Methods involving the addition of water yielded pH values higher than actually existed based on pH‐dependent chemical reactions. the Ultra M® micro electrode had problems with reproducibility and stability in the reduced‐moisture systems as well as the buffer solutions used for calibration. the Horiba Cardy pH meter and the surface pH electrode used directly on the surface of the reduced‐moisture solid system yielded pH values similar to those determined using pH‐dependent chemical reaction markers. the ability to measure the actual pH of reduced‐moisture solid systems would enable better understanding of potential modifications in product formulation needed to retard microbial growth and limit chemical reactions responsible for loss of shelf‐life.

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New Model Gel System for Studying Water Activity of Foods

Cited by 16 publications

References 24 publications

Surface bloom on improperly tempered chocolate

Surface bloom on improperly tempered chocolate

Aspartame Degradation Kinetics as Affected by pH in Intermediate and Low Moisture Food Systems

EVALUATION and COMPARISON of SIMPLE METHODS FOR pH MEASUREMENT of REDUCED-MOISTURE SOLID SYSTEMS

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