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Estimation of Grapefruit Juice Color
Degradation from Physicochemical Properties and
Thermal Inactivation Parameters of E. coli O157:H7

Alonzo A. Gabriel*, Errol John O. Ables, and Cecile Leah P. Tiangson-Bayaga

Laboratory of Food Microbiology and Hygiene
Department of Food Science and Nutrition, College of Home Economics
University of the Philippines Diliman, 1101 Quezon City, Philippines

*corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.


This study established models that quantify and predict the influences of intrinsic properties soluble solids (SS, 2-70°Brix) and dilution rate (%D, 0-80% water added), and Escherichia coli O157:H7 inactivation- related extrinsic  variables heating temperature (T, 47-97°C) and heating time (t, 0.5-60 min) on measured Commission Internationale de l'Eclairage (CIE) color space coordinates, and derived color parameters. The CIE L, a*, and b*, and respective differentials ΔL*, Δa*, and Δb* were significantly influenced by the individual effects of SS and %D. All these color parameters except a* and Δa* were influenced by the quadratic effects SS2 and %D2. Only b* and Δb* were significantly influenced by T. CIE °h*, Δ°h*, C*, ΔC*, and Δ°E were influenced by SS, D, SS2, and %D2. Only C* and Δ°C* were significantly influenced by T, while Δ°E* was influenced by the interaction of SS and %D. Validations showed that models had estimated values falling within acceptable ranges. The established models may be used together with other food quality and pathogen inactivation models in heated fruit juices, for a more comprehensive control of food safety and quality. This is the basic guiding principle of ‘Precision Food Processing,’ which to the authors’ knowledge is being introduced for the first time.

Fruit juice consumption is known to be a convenient means of complying with the recommended daily intake of fruits and vegetables (Gabriel et al. 2005). However, unpasteurized fruit juices were previously associated with outbreaks of infections of pathogens including Cryptosporidium parvum, Bacillus cereus, Escherichia coli O157:H7 and Salmonella enterica serovars (Vojdani et al. 2008). Because of the risk posed by these pathogens to consumers, the United States Food and Drug Administration ratified the Fruit Juice Hazard Analysis Critical Control Point (HACCP) (USDA & USDHHS 2001). . . . . read more

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