Microbial shelf life of coconut water subjected to various inoculation levels of Listeria monocytogenes and storage conditions.

The study determined the growth kinetic parameters of a cocktail of Listeria monocytogenes 1/2c and 4b strains in coconut water (pH 4.76, 5.0°Brix, 0.09% malic acid, aw 0.998) subjected to low (~2.0 log CFU/mL) and high (~4.0 log CFU/mL) contamination levels, and exposed to different storage temperatures (4 °C, 17 °C, 30 °C, and 35 °C). The pathogen proliferated in all tested conditions except in that with low contamination stored at 4 °C. Despite not growing at 4 °C, the pathogen was detectable throughout the storage period, which lasted for almost 400 h. In conditions where the pathogens proliferated, growth lag (tlag) ranged from 0.0 to 68.3 h. The growth rates (KG) ranged from 0.05 to 0.48 log CFU/h, while the final populations ranged from 6.3 to 8.7 log CFU/mL. Both storage temperature and contamination level significantly (P < 0.05) affected the growth parameters. Sanitary risk times (SRT) were determined with the microbiological shelf life (SL) of coconut water. In some of the conditions tested, SRT took place before SL (SRT < SL), emphasizing the importance of having good hygienic and manufacturing practices in place for such a vulnerable commodity.

Screening for heat-resistant reference yeast isolate in orange juice.

This study details a screening process for yeast species that may be used as reference microorganisms for mild thermal processing of orange juice. In the initial step, 17 different strains of spoilage yeasts with similar initial populations (6.0-7.0 log CFU/mL) and growth stage (middle stationary phase) were subjected to equal heating process (55 °C, 5 min) in Yeast Peptone Glucose Broth (pH 6.06). The change in populations observed ranged from 3.33 log CFU/mL (Pichia fermentans BFE-38) to 6.53 log CFU/mL (Torulaspora delbrueckii BFE-37). In the second step of the screening, 6 of the most resistant strains were further challenged in an orange juice suspending medium (pH 3.88, 10.02 °Brix, 0.82% citric acid) at different heating temperatures (50, 53, 55, 57, and 60 °C). The decimal reduction times (DT values) and thermal resistant constants (z values) were determined. Results showed that all tested yeasts exhibited first-order, log-linear inactivation behavior (R2 0.90-0.99). As expected, significant (P < 0.05) reduction in the DT values were observed with increasing temperature. P. fermentans BFE-38 exhibited the greatest Dvalues at 50-55 °C. However, the test isolate with the greatest z-value was found to be P. anomala (BIOTECH 2205).

Fates of pathogenic bacteria in time-temperature-abused and Holder-pasteurized human donor-, infant formula-, and full cream cow's milk.

This study was conducted to address the dearth in works that simultaneously compare the growth and inactivation behaviors of selected pathogens in different milk products. In worst-case scenarios where hygienic practices are absent and heavy microbiological contaminations occur, Salmonella enterica, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus multiplied in all samples at room temperature (27 °C). Most organisms readily proliferated with growth lag (tlag) values ranging from 0.00 to 5.95 h. Growth rates (KG) ranged from 0.16 to 0.67 log CFU/h. Sanitary risk times (SRTs) for a 1-log population increase ranged from 1.85 to 6.27 h, while 3.69-12.55 h were the SRTs determined for 2-log population increase. Final populations (Popfin) ranged from 7.11 to 9.36 log CFU/mL. Inactivation in heavily contaminated milk during Holder pasteurization revealed biphasic inactivation behavior with total log reduction (TLR) after exposure to 62.5 °C for 30 min ranging from 1.91 (90.8%) to 6.00 (99.9999%). These results emphasize the importance food safety systems in the handling of milk and milk products during manufacture and preparation.

Decontamination of dried whole black peppercorns using ultraviolet-c irradiation.

This study determined the efficacy of UV-C as a decontamination process against some foodborne bacteria in dried whole black peppercorns. Artificially-inoculated Salmonella enterica, Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus were subjected to UV-C with a surface irradiance of 0.43 mW/cm2 and were all found to exhibit a biphasic inactivation pattern with fast log-linear inactivation followed by a tail. Total log reductions (TLR) ranged from 1.92 (S. aureus) to 3.60 log CFU/g (E. coli O157:H7). Increasing the lamp number from 1 to 5 also linearly (R2 = 0.98) increased the surface irradiance from 0.43 to 1.70 and the TLR of the most resistant S. aureus from 1.92 to 2.62 log CFU/g. Quality evaluation showed very small, variable changes in color coordinates, which were not detected by a same/different test involving a 50-member sensory evaluation panel. Mercury deposition was not detected after a maximum exposure time of 90 min to 0.43 and 1.70 mW/cm2. Finally small, non-significant changes in the innate bacterial microflora of the black peppercorns were determined after 90 min-treatment using 1 lamp and 5 lamps, emphasizing the limitation of utility of UV-C as additional decontamination process for post-process-introduced microorganisms. Good Manufacturing Practices throughout the dried black peppercorn manufacturing process were recommended.

Relative validity of a food frequency questionnaire for pregnancy in a low-income urban community in the Philippines.

OBJECTIVE: The aim of this study was to develop and validate a food frequency questionnaire (FFQ) for pregnant women to identify those who are at risk for possible deficiencies in the key nutrients for pregnancy. METHODS: Pregnant women 18 to 39 y of age who availed themselves of perinatal services in community health centers in Makati City, Philippines were screened for the study. Five hundred eligible participants were asked to complete three 24-h food recalls for the development of the FFQ. A different set of participants with a total number of 100 were recruited for the validation of the questionnaire, which involved the use of the 3-d food record as the reference tool. The validity of the nutrient intakes obtained from the FFQ were measured against the values from the 3-d food record using Pearson's correlation coefficients and Bland-Altman plots. RESULTS: Significant correlations at P ≤ 0.05 were seen for energy, fat, riboflavin, cobalamin, and calcium. Pearson's correlation coefficients ranged from 0.016 to 0.32 for energy and nutrients. CONCLUSIONS: Acceptable agreements were seen for most of the nutrients. Possible deficiencies for key nutrients during pregnancy can be detected by the developed FFQ for Filipino pregnant women living in low-income urban communities with similar profiles.

Decimal reduction energies of UV-C-irradiated spoilage yeasts in coconut liquid endosperm.

The ultraviolet-C (UV-C) decimal reduction energy (DUV-C) values of 17 spoilage yeasts and their composited inoculum were determined in coconut liquid endosperm (pH 5.26, 5.8 °Brix, 0.04% malic acid, 0.17% w/v insoluble solids). Growth kinetic parameters of all the test yeast strains were first established to standardize the growth stage of the cells prior to inactivation studies. Approximately 4.0 to 5.0 log CFU/mL cells in the mid-stationary growth phase (30.3 to 39.9 h, 25 °C) were suspended in 4 mL turbulent flowing juice and subjected to UV-C irradiation at a surface irradiance range of 3.42 to 4.99 mW/cm2. Survivor populations after exposure to predetermined UV-C energy were enumerated, and were used to derive the DUV-C values using the linear regression and Baranyi and Roberts (1994) model fitting. Results show that the yeast strains exhibited either log-linear or biphasic inactivation behavior with inactivation lag. The most UV-C resistant spoilage yeast was found to be Cryptococcus albidus (LJY1) with DUV-C values of 122.72 and 214.89 mJ/cm2 determined from linear regression and model-fitting, respectively. The least UV-C resistant was Torulaspora delbrueckii (LYJ5) with a DUV-C of 17.34 (linear regression) and 17.35 mJ/cm2 (model-fitting). The DUV-C values determined from the model fitting were generally greater than those calculated from linear regression, although only those determined for C. albidus were significantly different. To the investigators' knowledge, this is the first report of the UV-C inactivation kinetic parameters of Kluyveromyces marxianus, Trichosporon cutaneum, Pichia anomala, and Meyerozyma guilliermondii and C. albidus in coconut liquid endosperm. The results of this study can be used in the establishment and validation of UV-C process schedules for coconut liquid endosperm and other similar commodities.

Ultraviolet-C resistance of selected spoilage yeasts in orange juice.

This study determined the ultraviolet-C (UV-C) dose necessary to reduce 90% population (DUV-C) of 17 spoilage yeasts and their composited inoculum in orange juice (pH 3.71, 11.60 °Brix, 0.55% citric acid, 2.46% w/v insoluble solids). Growth parameters of all test yeasts were first established to standardize the growth stage of the cells prior to harvesting and eventual UV-C challenge studies. Approximately 4-5 log CFU/ml cells in the mid-stationary growth phase (30.3 t0 39.9 h, 25 °C) were suspended in 4 ml turbulent flowing juice and subjected to UV-C irradiation at an incident surface irradiance of 3.64-4.97 mW/cm2. The inactivation rates of each yeast and their composited inoculum were determined using 2 methods namely, the linear regression and Baranyi and Roberts (1994) model-fitting. Results showed that the yeasts exhibited either log-linear or biphasic inactivation behavior with downward concavity or inactivation lag. Regardless of the method of determination, Cryptococcus albidus (LJY1) exhibited the significantly greatest (p < 0.05) UV-C resistance with DUV-C values of 1924.31 and 2174.63 mJ/cm2. On the other hand, Candida parapsilosis was determined to be least resistant with a DUV-C values of 245.83 and 357.88 mJ/cm2. Majority of the DUV-C values determined from the model-fitting were greater than those calculated from linear regression. However, only those determined for the composited inoculum were significantly different. The results of this study address knowledge gaps pertinent to the UV-C resistance of less studied spoilage yeast, and help in better understanding the utility of this non-thermal food processing technology.

Individual and combined efficacies of mild heat and ultraviolet-c radiation against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in coconut liquid endosperm.

This study determined the inactivation kinetic parameters of selected pathogens in heat, ultraviolet-C and combined heat-UV-C treated coconut liquid endosperm. Separate cocktails of Escherichia coli O157:H7, Salmonella enterica serovars, and Listeria monocytogenes strains were inoculated into coconut liquid endosperm (pH 5.15, TSS 4.4oBx, TA 0.062% malic acid, extinction coefficient (ε) at 254 nm of 0.0154 cm-1) for inactivation studies. Result showed that all organisms generally exhibited a log-linear heat inactivation behavior (R2 0.81-0.99). The E. coli O157:H7 cocktail (D55 = 19.75 min, D57 = 10.79 min, D60 = 3.38 min, and D63 = 0.46 min) was found to be significantly more resistant (P > 0.05) than the tested cocktail of L. monocytogenes (D55 = 11.68 min, D57 = 4.53 min, D60 = 1.82 min and D63 = 0.26 min) and S. enterica cocktail (D55 = 3.08 min, D57 = 2.60 min, D60 = 0.89 min and D63 = 0.25 min). Despite the differences in DT values, computed z values for L. monocytogenes cocktail (5.12 ±â€¯0.43 °C) and E. coli O157:H7 cocktail (4.95 ±â€¯0.12 °C) were not significantly different (P > 0.05), but were both significantly (P < 0.05) lower than that of S. enterica cocktail (7.10 ±â€¯0.15 °C). All test organisms also exhibited a generally log-linear UV-C inactivation behavior (R2 0.90-0.99) with E. coli O157:H7 cocktail (DUV-C = 25.26 mJ/cm2) demonstrating greatest resistance to UV-C than S. enterica (DUV-C = 24.65 mJ/cm2) and L. monocytogenes (DUV-C = 17.30 mJ/cm2) cocktails. The D55 values of each organism cocktail were used to calculate for the 3-log reduction heating process schedules, during which UV-C treatments were simultaneously applied. Lethal rates (F values) calculations in the combined processes revealed that within the 3-log reduction heating processes, co-exposure of UV-C resulted in 5.62 to 6.20 log reductions in the test organism populations. Heating caused 69.3, 97.2, and 67.4% of the reduction in E. coli O157:H7, S. enterica and L. monocytogenes cocktails, respectively. These results can be used as baseline data in the establishment of mild heat treatment in combination with UV-C process schedules for coconut liquid endosperm and other similar products.

A model for the influences of soluble and insoluble solids, and treated volume on the ultraviolet-C resistance of heat-stressed Salmonella enterica in simulated fruit juices.

This study was conducted to determine the effects of intrinsic juice characteristics namely insoluble solids (IS, 0-3 %w/v), and soluble solids (SS, 0-70 °Brix), and extrinsic process parameter treated volume (250-1000 mL) on the UV-C inactivation rates of heat-stressed Salmonella enterica in simulated fruit juices (SFJs). A Rotatable Central Composite Design of Experiment (CCRD) was used to determine combinations of the test variables, while Response Surface Methodology (RSM) was used to characterize and quantify the influences of the test variables on microbial inactivation. The heat-stressed cells exhibited log-linear UV-C inactivation behavior (R2 0.952 to 0.999) in all CCRD combinations with DUV-C values ranging from 10.0 to 80.2 mJ/cm2. The DUV-C values obtained from the CCRD significantly fitted into a quadratic model (P < 0.0001). RSM results showed that individual linear (IS, SS, volume), individual quadratic (IS2 and volume2), and factor interactions (IS × volume and SS × volume) were found to significantly influence UV-C inactivation. Validation of the model in SFJs with combinations not included in the CCRD showed that the predictions were within acceptable error margins.

Previous physicochemical stress exposures influence subsequent resistance of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes to ultraviolet-C in coconut liquid endosperm beverage.

This study investigated the influences of prior exposures to common physicochemical stresses encountered by microorganisms in food and food processing ecologies such as acidity, desiccation, and their combinations, on their subsequent susceptibility towards UV-C treatment in coconut liquid endosperm beverage. Cocktails of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes were separately subjected to gradually acidifying environment (final pH 4.46), exposed to abrupt desiccation by suspension in saturated NaCl solution (aw=0.85) for 4, 8, and 24h, and sequential acidic and desiccated stresses before suspending in the coconut beverage for UV-C challenge. The exposure times (D) and UV-C energy dose values (DUV-C) necessary to reduce 90% of the population of the different test organisms varied with previous exposures to different sublethal stresses, indicating possible influence of implicit microbial factors towards resistance to UV-C. All tested individual and combined stresses resulted in increased resistance, albeit some were not statistically significant. Non-stressed cells had D values of 3.2-3.5s, and corresponding DUV-C values of 8.4-9.1 mJ/cm(2). Cells exposed to previous acid stress had D values of 4.1-4.8s and corresponding DUV-C values of 10.7-12.5 mJ/cm(2). Prior exposure to desiccation resulted in D values of 5.6-7.9s and DUV-C values of 14.7-20.6 mJ/cm(2), while exposure to combined acid and desiccation stresses resulted in D values of 6.1-8.1s and DUV-C values of 15.9-21.0 mJ/cm(2). The D and DUV-C values of S. enterica after previous exposure to sequential acid (24 h) and desiccation (24 h) stresses were found significantly greatest, making the organism and physiological state an appropriate reference organism for the establishment of UV-C pasteurization process for the beverage.

Development and validation of a predictive model for the influences of selected product and process variables on ascorbic acid degradation in simulated fruit juice.

A predictive response surface model for the influences of product (soluble solids and titratable acidity) and process (temperature and heating time) parameters on the degradation of ascorbic acid (AA) in heated simulated fruit juices (SFJs) was established. Physicochemical property ranges of freshly squeezed and processed juices, and a previously established decimal reduction times of Escherichiacoli O157:H7 at different heating temperatures were used in establishing a Central Composite Design of Experiment that determined the combinations of product and process variable used in the model building. Only the individual linear effects of temperature and heating time significantly (P<0.05) affected AA reduction (%AAr). Validating systems either over- or underestimated actual %AAr with bias factors 0.80-1.20. However, all validating systems still resulted in acceptable predictive efficacy, with accuracy factor 1.00-1.26. The model may be useful in establishing unique process schedules for specific products, for the simultaneous control and improvement of food safety and quality.

Handler hygienic practices and aerobic plate counts of blenderized whole food tube feedings among selected tertiary and specialty hospitals in the National Capital Region, Philippines

OBJECTIVE: This work presents an updated and broad documentation of current practices of blenderized whole food tube feed (BTF) handlers (n=40) in some tertiary (n=8) and specialty (n=2) hospitals in the National Capital Region, Philippines.STUDY DESIGN: Descriptive study METHODS: Survey questionnaire and checklists which reflect processes and practices on BTF production were developed and pre-tested. These tools were then administered to 40 respondents from 8 tertiary and 2 specialty hospitals in the National Capital Region, Philippines. Observations were also recorded concerning BTF handling and administration as well as the sanitation of the preparation facility. The study further conducted additional interviews, and on-the-job observations with the same group of respondents in each of the test hospitals to validate survey responses and actual demonstration made in the documentation phase. RESULTS: Not all of the participating BTF handlers were observed to follow even simple personal and workplace hygienic practices. Moreover, not all BTF handlers had previous exposures to food safety systems training, and all test hospitals have yet to establish hazard analysis critical control point (HACCP) plans for BTF. The absence of accredited raw ingredient suppliers for the majority of the BTF facilities, failure to always wash raw materials prior to preparation, and the use of soft-boiled whole eggs were identified as sources of potential microbiological hazards. Total plate count was established to be as high as log10 7.19 CFU.ml-1. Ninety-three percent of the BTFs had plate counts exceeding the acceptable standard limit. CONCLUSION: The microbiological quality of the BTFs analyzed was attributed to the observed poor hygienic practices, as well as the inherent microflora of BTF ingredients. Familiarity with good manufacturing practices (GMPs), good hygienic practices (GHPs), and HACCP is recommended to improve the microbiological quality of BTFs. The results of this work may be used as basis for advancing efforts to further improve BTF safety, especially that the country had just recently ratified the Philippine Food Safety Act of 2013.

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.

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 (D(adapted)/D(non-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.

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

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.

Influences of simultaneous physicochemical stress exposures on injury and subsequent responses of E. coli O157:H7 to resuscitative and inactivative challenges.

E. coli O157:H7 responses namely, sublethal injury (% injury), subsequent resuscitation (lag) and growth parameters (k(G) and max population), and inactivation rates (D(25) and D(55)) were investigated following exposures to simultaneous pH (3.0-8.0), a(w) (0.93-0.99) and temperature stresses (3.0-62 degrees C). Multiple regression analyses showed that % injury was significantly influenced by a(w), a(w)(2), and temperature while the lag times were influenced by pH, pH-temperature interaction, and a(w)-temperature interaction. The measured growth parameters were however, not significantly influenced by any of the stressors. Acid inactivation rates (D(25)) in apple juice were influenced by a(w), pH-temperature interaction, and a(w)-temperature interaction; while the thermal inactivation rates (D(55)) in apple juice were influenced by pH and a(w) stresses. Results also showed that % injury alone may not correctly predict the subsequent resuscitation rates of the test organism at favorable growth conditions. The nature of the injury contributed by a specific stressor also influenced resuscitation. The occurrence of injury and loss of cell viability did not induce acid stress adaptation to the organism. However, exposures to very low- and low pH conditions that resulted in injury and loss in cell viability induced thermal cross protection in E. coli O157:H7. The results obtained in the study contribute in further understanding the behavior of the test organism after exposure to combinations of stresses commonly encountered in food and food processing ecologies.

Heat activation of Neosartorya and Talaromyces ascospores and enhancement by organic acids.

Neosartorya and Talaromyces are typical fungi capable of producing heat resistant ascospores responsible for the spoilage of processed fruit products. In this study, the heat activation rates of Neosartorya and Talaromyces ascospores were investigated in several suspending media at various heating temperatures. Ascospores were dispersed in pH 3.5 McIlvain buffer, organic acid/alcohol-supplemented McIlvain buffer and grape juice (pH 3.5, 5.0 degrees Brix) prior to heat treatments. In McIlvain buffer, the number of germinating ascospores increased logarithmically with longer exposure to heating at an test temperatures. Heat activation rates (k values) accelerated with increasing temperature. The calculated activation energy (Ea) values were similar among ascospores from the same genus, but the Ea of the test Neosartorya spp. were greater than that of the test Talaromyces spp. Greater k values were calculated from acetate-supplemented McIlvain buffer and grape juice. Similarly, normal- and branched-chain fatty acids were shown to enhance the heat activation rate of the ascospores in McIlvain buffer systems. These results could assist the food industry in designing adequate thermal processes for food products against the heat resistant fungi.

Estimation of water activity from pH and °Brix values of some food products.

In this study, a predictive model for the estimation of water activity (aw(25°C)) as a function of pH (1.00-8.00) and °Brix (0-82.00) values of simulated food solutions (SFS) was developed, through response surface methodology. Response fit analyses resulted in a highly significant (pH<0.0001) square root polynomial model that can predict aw(25°C) of SFS in terms of pH and °Brix values within the defined variable ranges. The linear, quadratic and interactive influences of pH and °Brix on aw(25°C) were all significant (pH<0.0001). Model validations in SFS and in a number of actual food systems showed that the model had acceptable predictive performance, as indicated by the calculated accuracy and bias indices.