Alonzo Gabriel

University of the Philippines, Department of Food Science and Nutrition, Faculty Member

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Alonzo Gabriel is a full Professor of Food Science and Technology, and a University Scientist at the Department of Food Science and Nutrition of the College of Home Economics, University of the Philippines-Diliman (UPD). He obtained his Bachelor of Science in Food Technology (2002, Department of Science and Technology Science Scholarship Recipient) and Master of Science in Food Science (2007) degrees from UPD. His PhD degree in Food Microbiology and Hygiene (2010, Japanese Ministry of Education, Culture, Sports, Science and Technology, Monbukagakusho Scholarship Recipient) was from Hiroshima University, Japan.

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Influences of vanillin and licorice root extract supplementations on the decimal reduction times of Escherichia coli O157:H7 in mildly heated young coconut liquid endosperm.

Food Control

Decimal Reduction Times of Acid-Adapted and Non-Adapted Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes in Young Cocos nucifera Linn. Liquid Endosperm.

Food Control

Influences of heating temperature, pH, and soluble solids on the decimal reduction times of acid-adapted and non-adapted Escherichia coli O157:H7 (HCIPH 96055) in a defined liquid heating medium

International Journal of Food Microbiology

The study characterized the influences of various combinations of process and product parameters ... more The study characterized the influences of various combinations of process and product parameters namely, heating temperature (53, 55, 57.5, 60, 62 °C), pH (2.0, 3.0, 4.5, 6.0, 7.0), and soluble solids (SS) (1.4, 15, 35, 55, 69°Brix) on the thermal inactivation of non-adapted and acid-adapted E. coli O157:H7 (HCIPH 96055) in a defined liquid heating medium (LHM). Acid adaptation was conducted by propagating cells in a gradually acidifying nutrient broth medium, supplemented with 1% glucose. The D values of non-adapted cells ranged from 1.43 s (0.02 min) to 304.89 s (5.08 min). Acid-adapted cells had D values that ranged from 1.33 s (0.02 min) to 2628.57 s (43.81 min). Adaptation did not always result in more resistant cells as indicated by the Log (Dadapted/Dnon-adapted) values calculated in all combinations tested, with values ranging from − 1.10 to 1.40. The linear effects of temperature and pH, and the joint effects of pH and SS significantly influenced the thermal resistance of non-adapted cells. Only the linear and quadratic effects of both pH and SS significantly influenced the D values of acid-adapted cells. Generally, the D values of acid-adapted cells decreased at SS greater than 55 °Brix, suggesting the possible cancelation of thermal cross protection by acid habituation at such SS levels. The relatively wide ranges of LHM pH and SS values tested in the study allowed for better examination of the effects of these factors on the thermal death of the pathogen. The results established in this work may be used in the evaluation, control and improvement of safety of juice products; and of other liquid foods with physicochemical properties that fall within the ranges tested in this work.

Influences of simultaneous physicochemical stresses on injury and subsequent heat and acid resistances of Salmonella Enteritidis in apple juice

Food Control

The effects of prior simultaneous pH (3.0–8.0), water activity, aw (0.93–0.99) and temperature (3... more The effects of prior simultaneous pH (3.0–8.0), water activity, aw (0.93–0.99) and temperature (3.0–62.0 °C) stresses on injury and subsequent resistance of Salmonella Enteritidis to acid (pH 3.78, 25 °C) and heating (pH 3.78, 55 °C) in apple juice were determined. Injury rates were significantly (P < 0.05) influenced by the linear effects of aw and temperature. Exposure to combinations (pH 4.0, aw 0.98, 15 °C) and (pH 5.5, aw 0.99, 32.5 °C) resulted in acid adaptation. Only the linear influence of prior aw stress significantly affected the subsequent acid resistance. Heat resistance was greatest after previous exposure to pH, aw and temperature ranges of 4.0–5.5, 0.96–0.98, and 15–50 °C, respectively. None of the stress factors significantly influenced subsequent heat resistance. These results provide a more realistic simulation of the effects of environmental stress factors on the behavior of S. Enteritidis in food and food processing ecologies; and contribute in further understanding the behavior of the pathogen for the improvement of evaluation and control of safety of apple juice and similar products.

Inactivation of Escherichia coli O157:H7 and spoilage yeasts in germicidal UV-C-irradiated and heat-treated clear apple juice

Food Control

The decimal reduction times (D) of individual and composited Escherichia coli O157:H7 or spoilage... more The decimal reduction times (D) of individual and composited Escherichia coli O157:H7 or spoilage yeasts in UV-C irradiated and heated (55 °C) clear apple juices (pH 3.68, 12.5 °Brix) were determined. Spoilage yeasts (D = 6.38–11.04 min) were found to be generally more UV-C resistant than E. coli O157:H7 (D = 0.5–2.76 min), while the opposite was observed in terms of thermal resistance (E. coli D=0.9–4.43 min; yeast D = 0.03–6.10 min). All spoilage yeast proliferated in the untreated juice (25 °C) while all E. coli strains were inactivated. Except for E. coli O157:H7 in UV-C irradiated apple juice, the composited inocula of both pathogenic and spoilage test organisms were less tolerant than the identified most resistant strain or species. The results of this study may be used in identifying appropriate target organisms, as well as the modes of inoculation, in challenge studies and eventually in the establishment and validation of process lethalities for apple juices and similar commodities.

Microbial inactivation in cloudy apple juice by multi-frequency Dynashock power ultrasound

Ultrasonics Sonochemistry

The study determined the efficacy of Dynashock wave power ultrasound as an alternative processing... more The study determined the efficacy of Dynashock wave power ultrasound as an alternative processing technique for apple juice against a number of pathogenic and spoilage microorganisms. The effects of several implicit, intrinsic and extrinsic properties on the Dynashock wave inactivation of the microorganisms were also investigated. Results showed that acid adaptation increased the resistance of Escherichia coli O157:H7 and Salmonella spp. but decreased that of Listeria monocytogenes. Spoilage yeast mixed inoculum composed of Debaryomyces hansenii, Torulaspora delbrueckii, Clavispora lusitaniae, Pichia fermentans and Saccharomyces cerevisiae was found to be more resistant than any of the adapted or non-adapted pathogens. Among the individual, acid-adapted E. coli O157:H7, the MN-28 isolate was found most resistant; while three other individual isolates had greater resistance than the composited E. coli inoculum. Increased in pulp content decreased the efficacy of Dynashock waves, but co-treatment with ultraviolet-C rays significantly enhanced inactivation in the cloudy apple juice. The results demonstrated the potential of Dynashock wave technology, together with other antimicrobial hurdles as alternative juice processing technique/s.

Thermal Death Time of Salmonella Typhimurium In Oyster Meat: Establishment and Application In a Heat-Treated Ceviche Recipe

Journal of Foodservice, Jan 1, 2008

Alonzo Gabriel

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