Untitled

Funder

Organizational Unit

Publications

Biochemical markers to predict internal browning disorders in ‘Rocha’ pear during storage under high CO2

Publication . Deuchande, Teresa; Larrigaudière, Christian; Guterres, Umbelina; Carvalho, Susana M. P.; Vasconcelos, Marta W.

BACKGROUND: The aim of this studywas to identify biochemical markers to predict internal browning disorders (IBD) in 'Rocha' pear. Fruits from five orchards were stored for 45 days under cold air followed by 100 days in browning-inducing controlled atmosphere (CA) conditions (1 kPaO(2) + 10 kPaCO(2)). RESULTS: Relationships between concentrations of ethanol (EtOH), acetaldehyde (AcDH) and ascorbic acid (AA), activities of peroxidase (POX) and polyphenoloxidase (PPO) and IBD incidence were established. The partial least square (PLS) model using the most promising markers, EtOH and AcDH, explained 89% of the variance in IBD incidence, whereas the univariate models based on the same markers explained between 89 and 94%. In contrast, the models based on AA levels and AA depletion rate only explained 57 and 82% of the variance in IBD incidence respectively. Model validation confirmed the robustness of EtOH for the prediction (R-2 = 0.91, RMSE= 11.1) and allowed proposing a threshold level of 30 mu L EtOH L-1 above which IBD may occur. Using this threshold value, the storage time limit associated with the occurrence of the first IBD symptoms was predicted with an acceptable RMSE of 9 days. CONCLUSION: Thiswork clearly identifies biochemical IBDmarkers for ` Rocha' pear and shows that dynamic changes in ethanol concentration during the beginning of storagemay be used to predict IBD development. Therefore the results presented herein represent a major step forward in the prediction of IBD in 'Rocha' pear.

2017Journal article

Restricted access

Mineral concentrations at harvest as novel markers to predict internal browning disorders in ‘Rocha’ pear during storage under high CO 2

Publication . Deuchande, Teresa; Carvalho, Susana M. P.; Larrigaudière, Christian; Vasconcelos, Marta W.

This study aimed to identify mineral markers at harvest capable of predicting internal browning disorders (IBDs) in pear (Pyrus communis L. cv Rocha) during storage, and develop an IBD predictive model. Fruit from five orchards harvested at two different maturity stages were stored for 45 days in cold air (−0.5 °C) followed by 100 days under controlled atmosphere (CA) (1 kPa O2 + 10 kPa CO2 at −0.5 °C). Concentrations of ten minerals were measured at harvest and a multivariate predictive model using this data was developed. The model explained 78% of variance in IBD incidence during storage and after validation it showed high accuracy (R2 = 0.97; RMSEP = 7.7%). Amongst the ten analysed minerals, copper (Cu), being significantly correlated to IBD incidence during storage, was the most promising IBD marker. This type of model may be a very useful tool to predict at harvest fruit’s sensitivity to IBD during storage allowing the selection of the most adequate storage conditions for the long-term storage of a fruit batch

2017Journal article

Restricted access

Transcriptional and biochemical regulation of internal browning disorder in 'Rocha' pear as affected by O-2 and CO2 concentrations

Publication . Deuchande, Teresa; Carvalho, Susana M. P.; Giné-Bordonaba, Jordi; Vasconcelos, Marta W.; Larrigaudière, Christian

The biochemical basis of internal browning disorders (IBD) in ‘Rocha’ pear has been linked to alterations in the antioxidant and fermentative metabolism. In order to further elucidate the involvement of these metabolic pathways on IBD development, we investigated their regulation at a metabolic and transcriptional level in pears that were stored under four distinct conditions: i) cold air (−0.5 °C); ii) standard controlled atmosphere (CA; 2 kPa O2 + 0.5 kPa CO2); iii) high CO2 (2 kPa O2 + 10 kPa CO2), and iv) high CO2 + low O2 (O2-switch: 60 d under high CO2 + 80 d under high CO2 and 1 kPa O2). Only the fruit stored under high CO2 were affected by IBD. The faster depletion of ascorbate in high CO2-stored fruit was associated with the down-regulation of glutathione reductase (PcGR) and ascorbate peroxidase (PcAPX) as well as a down-regulation of monodehydroascorbate reductase (PcMDHAR). The O2-switched fruit had the highest IBD incidence. Increased incidence in this sample was associated to a sharp increase in fermentation immediately after transfer to lower O2 atmosphere suggesting a synergistic effect between high CO2 and low O2 concentrations in IBD development. Overall, our results suggest that biochemical and transcriptional regulation of the antioxidant system affects IBD occurrence in ‘Rocha’ pear, and that fermentation, resulting from fruit exposure to low O2 concentrations, may further promote the browning process.

2017Journal article

Restricted access

Dynamic controlled atmosphere for prevention of internal browning disorders in ‘Rocha’ pear

Publication . Deuchande, Teresa; Carvalho, Susana; Guterres, Umbelina; Fidalgo, Fernanda; Isidoro, Nelson; Larrigaudière, Christian; Vasconcelos, Marta W.

This study aimed to evaluate the potential of two dynamic controlled atmospheres, DCA-CF (chlorophyll fluorescence sensor) and DCA-EtOH (ethanol sensor) when compared to controlled atmosphere (CA), in the prevention of internal browning disorders (IBD) in ‘Rocha’ pear stored under commercial conditions. Pears harvested at optimal maturity were stored for 145 days at 0.5 C and 95% relative humidity, under three atmospheres: (1) CA (3 kPa O2 þ 0.5 kPa CO2), (2) DCA-CF and (3) DCA-EtOH. At the end of storage, fruits in DCA-CF did not develop IBD while fruits in DCA-EtOH had an IBD incidence of 15 and 20% after 125 and 145 days of storage, respectively. The higher incidence of IBD under DCA-EtOH may be related to the higher levels of fermentative metabolites and to the lower ascorbate content. In contrast, the higher levels of ascorbate in DCA-CF showed that this technology contributes to maintaining the fruit's antioxidant potential. Collectively our results suggest that DCA-CF is an effective strategy to prevent IBD in ‘Rocha’ pear. On the contrary, the DCA-EtOH is not suitable to prevent the induction of fermentation and IBD development. The results also suggest that the IBD development in ‘Rocha’ pear is related to fermentative metabolism.

2016Journal article

Restricted access

Biochemical basis of CO2-related internal browning disorders in pears (Pyrus communisL. cv. Rocha) during long-term storage

Publication . Deuchande, Teresa; Larrigaudière, Christian; Giné-Bordonaba, Jordi; Carvalho, Susana; Vasconcelos, Marta W.

This study aimed at understanding the biochemical basis of internal browning disorders (IBDs) in 'Rocha' pear. For this purpose, the effects of storage under normal controlled atmosphere (CA) (3 kPa of O2 + 0.5 kPa of CO2) and IBD-inducing CA (1 kPa of O2 + 10 kPa of CO2) on the antioxidant and fermentative metabolisms and polyphenol oxidase (PPO) activity and phenolics concentration were studied. The higher IBD incidence in high CO2-stored fruits was positively correlated with fermentative metabolites and negatively with ascorbate and H2O2 concentrations, and it was linked to PPO activation. These results indicate that both the antioxidant and fermentative metabolisms are involved in the occurrence of IBD in 'Rocha' pear. From the integration of the biochemical and enzymatic data, a schematic model illustrating the effects of high CO2 and low O2 in 'Rocha' pears during long-term storage was constructed.

2016Journal article

Restricted access