Brandão, Teresa R.S.

Fundo, Joana F.

Miller, Fátima A.

Silva, Cristina L. M.

Sroy, Sengly

English

Repositório Institucional da Universidade Católica Portuguesa

Thermal and non-thermal Cantaloupe melon juice pasteurization: Assessment of the impact of ozone exposure on microbiological, physicochemical and bioactive characteristics  Sengly Sroy, Joana F. Fundo, Fátima A. Miller, Teresa R. S. Brandão, Cristina L. M. Silva* Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina – Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, 172, 4200-374 Porto, Portugal  Abstract  Thermal treatments are traditionally used in fruit juice processing. However, the biological activity of the most health-related compounds are intensely reduced. Alternatively, ozone-based processes have been exploited due to their potential for inactivating spoilage and pathogenic microorganisms, while being effective in products’ overall quality retention.  The aim of this study was to evaluate the impact of ozone and conventional pasteurization processes on microbiological decontamination and some quality attributes of Cantaloupe melon (Cucumis melo L var. reticulatus) juice. Melon juice samples were artificially inoculated with L. innocua (non-pathogenic surrogate of L. monocytogenes), used as indicator of the ozone treatment efficacy (initial concentration » 107 CFU/mL). Samples were exposed to gaseous ozone at a concentration of 7.7 g/L for 10 minutes. Intrinsic microflora (mesophylls and yeasts and molds), some physicochemical characteristics (pH, color and soluble solids content) and bioactive compounds (total phenolics and vitamin C) were evaluated. A thermal treatment at 72 °C for 15 seconds was also performed seeking comparison of ozone exposure impact. In terms of mesophylls (initial loads of 5.8±1.0 log-cycles), ozone did not affect significantly microbial loads (5.6±0.6 log-cycles), while pasteurized samples reduced significantly to 3.8±1.0 log-cycles. For yeasts and molds (initial loads of 4.3±0.4 log-cycles), both treatments affected significantly the results, being the pasteurization more effective (3.4±1.2 and 0.9±0.2 log-cycles after ozone and thermal treatment, respectively). After ozone exposure, L. innocua was not detected in juice samples; pasteurization allowed a reduction of 5.2±0.2 log-cycles. Ozone and thermal treatments did not affect soluble solids content, pH and total phenolics content, when compared to fresh juice samples. However, distinct color differences were observed in juices after application of both treatments. Vitamin C was highly retained in ozone treated juices (68%), when compared to pasteurized ones (39%). Since ozone treatment was effective on L. innocua inactivation and allowed a retention of most of quality parameters analyzed, this technology can be considered as a promising alternative to traditional pasteurization of fruit juices.   Keywords:  Ozone treatment, thermal pasteurization, Cantaloupe melon juice, preservation, quality    

Thermal and non-thermal Cantaloupe melon juice pasteurization: Assessment of the impact of ozone exposure on microbiological, physicochemical and bioactive characteristics

Introduction ObjectivesMethods Results and DiscussionConclusionsAcknowledgementsJoana F. Fundo and Teresa R.S. Brandão gratefully acknowledge their Post-Doctoral Grants (SFRH/BPD/109519/2015 and SFRH/BPD/101179/2014, respectively) to Fundação para a Ciência e a Tecnologia (FCT).This work was supported by National Funds from FCT - Fundação para a Ciência e a Tecnologia through project UID/Multi/50016/2013.The aim of this study was to evaluate the impact of ozone and conventionalpasteurization processes on Cantaloupe melon juice, assessing:• microbiological decontamination - Listeria innocua (non-pathogenic surrogate of L.monocytogenes) and intrinsic microflora (total mesophylls and yeasts and molds)• quality attributes - physicochemical (color, pH and soluble solids content) andbioactive compounds (total phenolics and vitamin C)Sengly Sroy, Joana F. Fundo, Fátima A. Miller, Teresa R. S. Brandão and Cristina L. M. Silva*Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina – Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, 172, 4200-374 Porto, Portugal* Corresponding author: clsilva@porto.ucp.ptThermal and non-thermal Cantaloupe melon juice pasteurization: Assessment of the impact of ozone exposure on microbiological, physicochemical and bioactive characteristics Cucumis melo L. var. reticulatus300 mL melon juiceThree replicates were performed ; ANOVA + Post-hoc testsData analysisCantaloupe melon is a commonly consumed fruit worldwide due to its nutritional andorganoleptic properties, being extensively used as raw material in fruit juices industry.However, when fresh fruit juices are not subject to any decontamination treatment,they become more susceptible to microbial spoilers and pathogens, which may affecthuman health.Thermal treatments are traditionally used in fruit juice processing. However, thebiological activity of the most health-related compounds are intensely reduced.Alternatively, ozone-based processes have been exploited due to their potential forinactivating spoilage and pathogenic microorganisms, while being effective in products’overall quality retention.Microbiological analysisSpectrophotometer, Model 5625, ATI Unicam = 750 nmTotal phenolicsExtraction with methanolPhysicochemical parametersTotal phenolics & Vitamin CQuality analysis pH meter GL 22pH SSC (ºBrix)RefractometerPalette PR-32 Table 1. Effect of thermal pasteurization and ozone treatment on juice microflora.The values are mean±margin of confidence interval at 95%.Intrinsic microfloraJuiceFresh Pasteurized OzonatedTotal mesophylls (CFU/mL) 5.77 ±1.04b 3.83 ± 1.01a 5.60 ± 0.57bYeasts and molds (CFU/mL) 4.33 ± 0.40c 0.94 ± 0.19a 3.43 ± 1.25bQualityDecontamination Ozone and thermal treatments did not affect soluble solids content, pH and total phenolics content, when compared to fresh juice samples. Distinct color differences were observed in juices after application of both treatments. Vitamin C was highly retained in ozone treated juices (68%), when compared to pasteurized ones (39%). Since ozone treatment was effective on L. innocua inactivation and allowed a retention of most of quality parameters analyzed, this technology can be considered as a promising alternative totraditional pasteurization of fruit juices.Intrinsic microfloratotal mesophylls yeasts and molds  Juice samples were artificially inoculated with L. innocua300 mL melon juiceL. innocuasuspension N0 ≈ 105 CFU/mLGaseous ozone exposure for 10 min at 4°C at 7.7 g/LThermal pasteurizationOzone treatment72°C for 15 secondsHPLC JascoVitamin CPasteurizationOzone01234567890 2 4 6 8 10 12Log (N)Treatment time (minutes)Figure 1. Inactivation of L. innocua in melon juice after ozone and pasteurization processing.Data represents mean values and bars the confidence intervals at 95%.5-log reduction ofL. innocua Quality attributeJuiceFresh Pasteurized OzonatedColor (TCD) - 2.35  1.38 3.71  2.93pH 6.35  0.13a 6.53  0.41a 6.30  0.23aSSC (°Brix) 10.65  1.02a 10.65  1.02a 10.65  0.79aTotal phenolics (g/mL) 182.27  24.81a 173.81  31.86a 199.85  48.79aTotal vitamin C (mg/100mL) 23.84  5.15c 9.25  2.27a 16.11  2.37bOzone treatmentWhen compared to pasteurization, ozone treatment allowed better vitamin C retentionSampleN0 ≈ 105 CFU/mLN0 ≈ 104 CFU/mLFresh• after 15 sec of pasteurization • after 10 min of ozone treatmentFor a given microorganism group, values with different letters differ significantly (p<0.05).Table 2. Effect of thermal pasteurization and ozone treatment on juice quality attributes.The values are mean±margin of confidence interval at 95%.For a given attribute, values with different letters differ significantly (p<0.05).• no impact on total mesophylls• 1-log reduction of yeasts and moldsColorimeterMinolta CR-400Color

Thermal and non-thermal cantaloupe melon juice pasteurization: assessment of the impact of ozone exposure on microbiological, physicochemical and bioactive characteristics

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Thermal and non-thermal Cantaloupe melon juice pasteurization: Assessment of the impact of ozone exposure on microbiological, physicochemical and bioactive characteristics

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Repositório Institucional da Universidade Católica Portuguesa