Respiration rate and its effect on mass loss and chemical qualities of 'Fuyu' persimmon fruit stored in controlled atmosphere

Taxa respiratória e seu efeito na perda de massa e qualidades químicas de caqui 'Fuyu' armazenado em atmosfera controlada

NOTE

CROP PRODUCTION

Respiration rate and its effect on mass loss and chemical qualities of 'Fuyu' persimmon fruit stored in controlled atmosphere

Taxa respiratória e seu efeito na perda de massa e qualidades químicas de caqui 'Fuyu' armazenado em atmosfera controlada

Auri Brackmann^I,1; Fabio Rodrigo Thewes^II; Rogério de Oliveira Anese^III; Vanderlei Both^IV; Adriano Roque de Gasperin^V

^IDepartamento de Fitotecnia, Universidade Federal de Santa Maria (UFSM), 97105-900, Santa Maria, RS, Brasil. E-mail: [e-mail]

^IICurso de Agronomia, UFSM, Santa Maria, RS, Brasil

^IIIPrograma de Pós-graduação em Agronomia, UFSM, Santa Maria, RS, Brasil

^IVEmpresa de Assistência Técnica e Extensão Rural (Emater), Porto Xavier, RS, Brasil

^VEmater, Candelária, RS, Brasil

ABSTRACT

The objective of this research was evaluate the effect of two CO₂ partial pressures in ultra-low oxygen on the mass loss in function of respiration, oxygen consumption, respiratory rate and other characteristics of 'Fuyu' persimmon during 12 weeks in controlled atmosphere (CA) storage at temperature of -0,5°C. For thus, one experiment was carried out with the followed CA condition: [1] 0.15 kPa O₂ plus 2.0 kPa CO₂ and [2] 0.15 kPa O₂ plus 6.0 kPa CO₂. On this study was verified that the respiration (carbon dioxide production) was responsible for 24% of total mass loss. The total mass loss is significantly affected by the controlled atmosphere storage. The 2.0 kPa CO₂ promotes changes in the respiratory quotient during the storage period and keep higher mass loss in function of respiration (CO₂ losses) and lower soluble solids after storage.

Key words: Diospyrus kaki, postharvest, oxygen uptake, CO₂ losses, soluble solids.

RESUMO

O objetivo deste trabalho foi avaliar o efeito de duas pressões parciais de CO₂ em ultrabaixo oxigênio sobre a perda de massa em função da respiração, consumo de O₂, taxa respiratória e outras características de caqui 'Fuyu', durante 12 semanas de armazenamento, em atmosfera controlada na temperatura de -0,5°C. Para tanto, um experimento foi conduzido com as seguintes condições de AC: [1] 0,15 kPa O₂ mais 2,0 kPa CO₂ e [2] 0,15 kPa O₂ mais 6,0 kPa CO₂. A respiração (produção de gás carbônico) foi responsável por 24% do total de perda de massa. A perda de massa é significativamente afetada pelas condições de atmosfera controlada. 2,0 kPa CO₂ promove mudanças no quociente respiratório durante o armazenamento, proporciona maior perda de massa em função da respiração e menor concentração de sólidos solúveis depois do armazenamento.

Palavras-chave: Diospyrus kaki, pós-colheita, consumo de oxigênio, perda de CO₂, sólidos solúveis.

During storage time, one of the most important events of fruit is the respiration, where oxygen (O₂) uptake and carbon dioxide (CO₂) production occurs at the same scale, in aerobic conditions (STEFFENS et al., 2007).With the respiration process occurs soluble solids and titratable acidity consumption. The decrease in respiratory rates during Postharvest life of the fruit can be achieved by reducing the temperature and use of controlled atmosphere storage (STEFFENS et al., 2007; BRACKMANN et al., 2008). Throughout the storage, CO₂ partial pressure has significant effect in respiration rate at aerobic condition, but in ultra-low oxygen (ULO) condition its effect is not clear and more researches are needed.

Furthermore, the respiration rate influences the mass loss, because there are carbon losses. However, the major part of mass loss is in function of water vapor loss. Some authors reported that mass loss is an important contributor to the maintenance of high quality during postharvest in apples (MAGUIRE et al., 2000; BRACKMANN et al., 2007) and peaches (PINTO et al., 2012). However, these studies do not distinguish the effect of water loss and dioxide carbon losses on total mass loss and are not accompanied by the respiration (CO₂ production) and O2 uptake in real time throughout the controlled atmosphere storage period.

The objective of this research was to evaluate the effect of two different CO₂ partial pressures associated to ULO storage, on the mass loss in function of respiration, oxygen uptake, respiratory rate and other variables of 'Fuyu' persimmons stored during 12 weeks in CA at -0.5°C.

The experimental material was obtained from a commercial orchard located in the city of Farroupilha, Rio Grande do Sul (Brazil), in 2012. At the harvest, the fruit showed 0.83meq 100mL^-1 titratable acidity, soluble solids of 15.5 °Brix, 1.21mL CO₂ kg^-1 h^-1 respiration rate, 14.2mL CO₂ L^-1 internal CO₂. The fruits were selected by eliminating injured fruit and were stored under two controlled atmosphere conditions: [1] 0.15 kPa of O₂ plus 2.0 kPa of CO₂ and [2] 0.15 kPa of O₂ plus 6.0 kPa of CO₂ at the temperature of -0,5°C, during three months in chambers of 0.233m³. The relative humidity in the chambers was maintained at 95% (±1%).Completely randomized statistical scheme was used, with fourteen replications with ten fruits each.

The variables evaluated were: a) respiratory rate (evaluated by CO₂ production during storage) and b) O₂ uptake during storage, which were evaluated with a gas analyzer during all the days of storage, the results were expressed in mL CO₂ kg^-1 h^-1 and mL O₂ kg^-1 h^-1, respectively; c) respiration quotient: obtained by the quotient of CO₂ production and O₂ consumption (ΔCO₂/ΔO₂); d) total mass loss: obtained by weighting the fruit before and after the storage. The data were expressed in percentage of the initial mass; e) mass loss in function of respiration: calculated by the relation between mass loss because of respiration, in function of CO₂ accumulation in the chamber, and its contribution on total mass loss. Data expressed in percentage of total mass loss; f) mass loss in function of water vapor loss: obtained by subtraction between total mass loss and mass loss in function of respiration, data expressed in percentage of total mass loss; g) soluble solids: evaluated by refractometry from the juice of the samples, data expressed in °Brix; h) titratable acidity: determined by titration of a solution of 10mL fruit juice diluted in 100mL of distillated water, with NaOH 0.1N. The results were expressed in meq 100mL^-1.

For each variable, was done a variance analysis (ANOVA), being the means submitted to regression analysis and Tukey test with 5% of probability of error. The data expressed in percentage were transformed with the formula arc.sin ((x/100)0,5) before submitted to variance analyses.

During storage, respiration rate was completely different on the two CO₂ partial pressures (Figure 1A and 1D). On the lowest CO₂ partial pressure (2.0 kPa) the respiratory rate increased with the storage time. However, when fruit were stored in 6.0kPa CO₂ the respiration rate decreased with the storage time. These results indicated that the higher CO₂ partial pressure reduced respiration even under ULO condition. The table 1 shows that the respiratory rate was lower in the higher CO₂ level. This lower respiratory rate occurs because the CO₂ is produced in tricarboxylic acid cycle, and the increase of partial pressure in the storage chamber reduced the CO₂ production pathways (TAIZ & ZEIGER, 2009). Another study demonstrated reduction in respiration with the increased of CO₂ partial pressure (STEFFENS et al., 2007).

The O₂ uptake was similar on both treatments, where occurs a linear decreasing during the storage time (Figure 1B and 1E), but fruit stored at 2.0kPa CO₂ have a higher angular coefficient (-0.0105) than fruit stored at 6.0 kPa CO₂ (-0.0049). The higher angular coefficient indicated that the fruit stored at 2.0 kPa CO₂ showed a marked decreasing in O₂ uptake during storage than fruit stored at 6.0 kPa CO₂. However, the total O₂ uptake was significantly higher in fruit stored in the lowest CO₂ partial pressure (Table 1).These decreasing in O₂ uptake linked with increasing CO₂ production throughout the storage, increased the respiratory quotient on the fruit stored at this condition (2.0 kPa CO₂) (Figure 1C).Similar results were reported in apples (SAQUET & STREIF, 2002).The result indicated that fruit stored at this CO₂ level increased the anaerobic metabolism from the onset to the end of storage, because higher respiratory quotient values showed greater anaerobic metabolism (SAQUET & STREIF, 2002). However, when fruits were stored in 6.0 kPa CO₂ the anaerobic metabolism on the beginning and end was the same, because the respiratory quotient was the same during storage time (Figure 1F). After three months of storage the average respiratory quotient was similar in both CO₂ partial pressures (Table 1).

Some studies have suggested that higher mass loss can keep higher postharvest quality, because it increases the gas exchange in apples (BRACKMANN et al., 2007) and peaches (PINTO et al., 2012). However, not all mass loss increases the gas exchange in fruit, but only the mass loss as a result of water vapor loss. At this study it was verified that the respiration have a significant effect on mass loss, being responsible for 24% of the total mass loss, and the result were similar than the obtained in apples stored at the same relative humidity, in which about 20% of mass is in function of respiration rate (MAGUIRE et al., 2000). The table 1 shows that the higher respiratory rate on fruit stored with 2.0 kPa CO₂ culminated in higher mass loss in function of respiration rate. Inverse result was obtained with 6.0 kPa CO₂ in relation to mass loss resulted from water vapor losses. The total mass loss was higher in fruit stored with 2.0 kPa CO₂ as a result of the higher respiration rate of this treatment.

The higher respiratory rate and O₂ uptake of fruit stored with 2.0 kPa of CO₂ (Table 1) result in chemical changes in fruit. Significant effect was verified in soluble solids contents, which showed a reduction in fruits stored with 2.0 kPa CO₂. However, the soluble solids contents are higher on fruit submitted to 6.0 kPa CO₂ because there is higher mass loss in function of water vapor loss. Another studies showed that the mass loss as a result of water loss increased de accumulation of soluble solids during storage (BRACKMANN et al., 2004; BRACKMANN et al., 2007; PINTO et al., 2012). In general, the persimmon fruits have low acidity and its concentration does not change during the storage, and is not affected by the CO₂ concentration (Table 1).

In 'Fuyu' persimmon the total mass loss is significantly affected by controlled atmosphere storage conditions. 2.0 kPa CO₂ promotes changes in respiratory quotient during storage time, keep higher mass loss in function of respiration (CO₂ losses) and lower soluble solids after storage. Titratable acidity is not affected by the two CO₂ partial pressures under ULO treatments.

ACKNOWLEDGEMENTS

To Conselho Nacional de Desenvolvimento Científico e Tecnológico, Coordenação de aperfeiçoamento de Pessoal e de Nível Superior and Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, for financial support.

Received 06.26.12

Approved 10.07.13

Returned by the author 01.29.14

CR-2012-0870.R2

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Autor para correspondência.

Publication Dates

• Publication in this collection
  01 Apr 2014
• Date of issue
  Apr 2014

History

• Received
  26 June 2012
• Accepted
  07 Oct 2013