Joaquina Pinheiro 1* , Carla Alegria 2 , Marta Abreu 2 , Isabel Fernandes 2 , Elsa M. Gonçalves 2 , Cristina L.M. Silva 1 1 Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Porto, Portugal Heat Treatment Effects on Physical-chemical and Microbiological Quality of Whole Tomato (Lycopersicum esculentum L.) Fruit during Storage Day 0 Day 7 Day 14 2 Departamento de Tecnologia das Indústrias Alimentares, Instituto Nacional de Engenharia, Tecnologia e Inovação, Lisboa, Portugal * joaquina.pinheiro@mail2.ineti.pt OBJECTIVE OBJECTIVE Heat treatment (HT – 42 ºC/30 min) effects on quality attributes of whole tomatoes (untreated and heat treated), at two ripening stages (turning RESULTS After HT:  No significant Turning Untreated Turning HT Pink L* = 46.59 ± 1.99 a* = -3.33 ± 0.36 b* = 24.13 ± 0.87 MF = 7.35 ± 1.31 L* = 52.19 ± 4.44 a* = -8.35 ± 1.11 b* = 24.41 ± 2.14 MF = 10.24 ± 1.98 L* = 49.54 ± 2.03 a* = 2.51 ± 0.52 b* 24 38 1 10 L* = 50.05 ± 3.02 a* = 3.87 ± 0.84 b* = 24.77 ± 2.11 MF = 8.87 ± 1.64 L* = 51.51 ± 2.70 a* = 1.63 ± 0.26 b* = 25.94 ± 2.14 MF = 9.44 ± 1.64 L* = 51.12 ± 2.15 a* = 9.64 ± 0.70 b* 27 38 2 44 Tomato is a typical climacteric fruit characterized by a rapid softening, change and pink), during storage at 7 ºC, 85% RH for 14 days. INTRODUCTION  No significant differences (p>0.05) were found on colour parameters.  HT did not affect the firmness of tomatoes (p>0.05). After storage  Tomato colour d l d f Untreated Pink HT b* = 24.38 ± 1.10 MF = 8.55 ± 0.96 L* = 45.98 ± 1.51 a* = 13.17 ± 1.24 b* = 24.64 ± 2.02 MF = 8.51 ± 2.17 b* = 27.38 ± 2.44 MF = 7.54 ± 1.20 L* = 47.06 ± 1.58 a* = 10.20 ± 0.93 b* = 23.93 ± 2.57 MF = 7.42 ± 0.73 Fig. 4 – Photographs of untreated and HT tomatoes at ripening stage, turning and pink (values CIELab parameters & maximum force). in colour and fungal development, once the ripening process is initiated. These quality changes can be a limitation for the product shelf-life and commercialization. Recently, studies on postharvest treatments, namely HT, applied on different whole fruits and vegetables demonstrated a decay control and a positive effect on the ripening process (1,2,3) . developed from green (chlorophylls) to red (lycopene).  Both treated samples denoted maintenance of maximum force during storage (p>0.05). Untreated HT_Turning Untreated HT Turning  CIELab parameters (L*,a*, b*, 12 replicates) MATERIALS & METHODS Turning Pink Fig 2 Minolta CR 300 Untreated Tomatoes Quality Attributes (analysis at 0, 7 and 14 days) 0 2 4 6 8 0 2 4 6 8 10 12 14 16 POD Activity (Abs.min.ml-1) Storage period (days) 20% (p>0.05) 0 1 2 3 4 5 0 2 4 6 8 10 12 14 16 PME Activity (Abs.min.ml -1 ) Storage period (days) Untreated HT_Turning 45% (p>0.05)  Texture (Maximum force – MF, N, 24 replicates)  pH & soluble solids content (SSC, 6 replicates)  Peroxidase (4) & pectinmethylesterase activity (5) (POD & PME, Abs.min.ml -1 , 6 replicates)  Moulds and yeasts (6) (Log CFU g -1 3 replicates) Fig. 2 – Minolta CR -300 Fig. 3 – TA-HDi Texture Analyser Heat Treatment (42ºC ± 0.5ºC) Cooling & Drying Storage period (days) 0 2 4 6 8 POD Activity (Abs.min.ml-1) Untreated HT_Pink 30% (p>0.05) Storage : POD (p<0.05) in all samples Storage period (days) 0 1 2 3 4 5 PME Activity (Abs.min.ml -1 ) Untreated HT_Pink Storage : PME in untreated samples & PME in HT samples (p>0.05) 33% (p<0.05)  Moulds and yeasts (Log 10 CFU.g 1 , 3 replicates). Storage (14 days at 7ºC&855%RH) Fig. 1 – Flow diagram of untreated and heat treated tomatoes Data Analysis : 9 Analysis of variance (Statistic v.7.0) – significant differences after HT and during storage between turning and pink tomatoes were detected with Scheffé test (significant at p < 0.05). Table 1 – Initials values of quality attributes of untreated turning and pink tomatoes (mean ± standard deviation). 0 0 2 4 6 8 10 12 14 16 Storage period (days) 0 0 2 4 6 8 10 12 14 16 Storage period (days) Fig. 5 – Evaluation of POD activity (Abs.min/ml) of unheated and heat treated turning tomatoes (HT_Turning) and heat treated pink tomatoes (HT_Pink) stored at 7ºC for 14 days. Fig. 6 – Evaluation of PME activity (Abs.min/ml) of unheated and heat treated turning tomatoes (HT_Turning) and heat treated pink tomatoes (HT_Pink) stored at 7ºC for 14 days. 6,0 .g-1)] Untreated HT_Turning 60 f.u.g-1)] Untreated HT_Pink Storage: HT samples < moulds & yeasts than untreated (p>0.05) References: 1 – Ali, Md.S., Nakano, K. & Maezawa, S. (2004). Combined effect of heat treatment and modified atmosphere packaging on the color development of cherry tomato. R h t P th t Bi l d T h l 34 (1) 113 116 Ripening Stage L* a* b* MF (N) SSC (ºBrix) pH POD (Abs.min.ml -1 ) PME (Abs.min.ml -1 ) Moulds & Yeasts (Lo 10 CFU.g -1 ) Turning 48.07 ± 2.25 -9.57 ± 1.18 22.90 ± 3.34 10.15 ± 1.77 3.98 ± 0.53 4.29 ± 0.04 5.45 ± 0.95 1.87 ± 0.19 3.02 ± 0.69 Pink 48.64 ± 2.95 1.81 ± 0.36 21.99 ± 3.31 8.38 ± 1.84 4.05 ± 0.14 4.29 ± 0.03 2.56 ± 0.15 2.53 ± 0.34 3.02 ± 0.69 0,0 1,0 2,0 3,0 4,0 5,0 0 2 4 6 8 10 12 14 16 Moulds & Yeats [Log10 (c.f.u. Storage period (days) 0,0 1,0 2,0 3,0 4,0 5,0 6,0 0 2 4 6 8 10 12 14 16 Moulds & Yesats [Log10 (c.f Storage period (days) Fig. 7 – Evaluation of moulds and yeasts of unheated and heat treated turning tomatoes (HT_Turning) and heat treated pink tomatoes (HT_Pink) stored at 7ºC for 14 days. Acknowledgements: The author Joaquina Pinheiro would like to thank Fundação para a Ciência e a Tecnologia (PhD grant SFRH/BD/24913/2005). Research note. Postharvest Biology and Technology, 34 (1): 113-116. 2 – Fallik, E. (2004). Review - Prestorage hot water treatments (immersion, rinsing and brushing). Postharvest Biology and Technology, 32(1): 125-134. 3 – Polenta, G., Lucangeli, C., Budde, C., González, C.B. & Murray, R. (2006). Heat and anaerobic treatments affected physiological and biochemical parameters in tomato fruits. LWT-Food Science and Technologies, 39 (1): 27-34. 4 - Yahia, E.M., Soto-Zamora, G., Brecht, J.K. & Gardea, A. (2007). Postharvest hot air treatment effects on the antioxidant system in stored mature-green tomatoes. Postharvest Biology and Technology, 44 (2): 107-15. 5 - Hagerman, A.E. & Austin, P.J. (1986). Continuous spectrophotometric assay for plant pectin methylesterase. Journal Agricultural and Food Chemistry, 34(3): 440- 444. 6 - NP 3277 (1987) – Contagem de bolores e leveduras. Instituto Português da Qualidade. After HT and during storage: pH did not differ and SSC increased on HT tomatoes (0.3 units and 0.9 on turning and pink) . CONCLUSIONS HT (42ºC/30min) seems to be more effective on quality maintenance and decrease of fungal development compared with untreated tomatoes, during cold storage of whole fresh tomatoes.