Oxygen Concentration Affects Chlorophyll Fluorescence in Chlorophyll-containing Fruit and Vegetables

Abstract

<jats:p>A new chlorophyll fluorescence (F) sensor system called FIRM (fluorescence interactive response monitor) was developed that measures F at low irradiance. This system can produce a theoretical estimate of Fo at zero irradiance for which we have coined a new fluorescence term, Fα. The ability of Fα to detect fruit and vegetable low-O<jats:sub>2</jats:sub> stress was tested in short-term (4-day) studies on chlorophyll-containing fruit [apple (<jats:italic>Malus sylvestris</jats:italic> (L.) <jats:italic>Mill.</jats:italic> var. <jats:italic>domestica</jats:italic> (Borkh.) Mansf.), pear (<jats:italic>Pyrus communis</jats:italic> L.), banana (<jats:italic>Musa</jats:italic> ×<jats:italic>paradisiaca</jats:italic> L.), kiwifruit (<jats:italic>Actinidia deliciosa</jats:italic> C.S. Liang &amp; A.R. Ferguson), mango (<jats:italic>Mangifera indica</jats:italic> L.), and avocado (<jats:italic>Persea americana</jats:italic> Mill.)] and vegetables (cabbage (<jats:italic>Brassica oleracea</jats:italic> L. Capitata Group), green pepper (<jats:italic>Capsicum annuum</jats:italic> L. Grossum Group), iceberg and romaine lettuce (<jats:italic>Lactuca sativa</jats:italic> L.)). In all of these fruit and vegetables, Fα was able to indicate the presence of low-O<jats:sub>2</jats:sub> stress. As the O<jats:sub>2</jats:sub> concentration dropped below threshold values of 0 to 1.4 kPa, depending on the product, the Fα value immediately and dramatically increased. At the end of the short-term study, O<jats:sub>2</jats:sub> was increased above the threshold level, whereupon Fα returned to approximately prestressed values. A 9-month study was undertaken with `Summerland McIntosh' apple fruit to determine if storing the fruit at 0.9 kPa O<jats:sub>2</jats:sub>, the estimated low O<jats:sub>2</jats:sub> threshold value determined from Fα, would benefit or damage fruit quality, compared with threshold + 0.3 kPa (1.2 kPa O<jats:sub>2</jats:sub>) and the lowest recommended CA (1.5 kPa O<jats:sub>2</jats:sub>). After 9 months, the threshold treatment (0.9 kPa) had the highest firmness, lowest concentration of fermentation volatiles (ethanol, acetaldehyde, ethyl acetate) and lowest total disorders. Sensory rating for off-flavor, flavor and preference indicated no discernible differences among the three treatments.</jats:p>

Non‐destructive evaluation of ripening and quality traits in apples using a multiparametric fluorescence sensor

“…Measurement of the dark‐state fluorescence, F 0 , has been suggested in order to assess sugar accumulation in grape berries non‐invasively during ripening 31. Applications of chlorophyll fluorescence–kinetic measurements to apples involve monitoring fruit storage,32–34 and assessing stress conditions9 and ripening 34. Steady‐state and maximum chlorophyll fluorescence in apples under natural light has been used to follow fruit development during the growing season 35.…”

Organic food processing: a framework for concept, starting definitions and evaluation

“…It uses a fluorescence‐based technology to monitor the responses of fruit to low oxygen and has been shown to be an effective alternative to DPA treatment for complete control of scald and apple quality preservation . This technique involves the use of a non‐destructive monitoring system of fruit chlorophyll fluorescence, which allows the detection of low‐O 2 stress before development of associated disorders in apple fruit . This system, by indicating when the fruit is under low‐O 2 stress during storage, allows for the dynamic adaptation of the atmosphere composition in the controlled atmosphere room to an O 2 level lower than that set in ultra‐low oxygen storage, but still tolerated by fruit; in this way it becomes possible to optimise the greatest benefits of ultra‐low oxygen without producing detrimental effects due to anaerobic conditions .…”

Innovative and Integrated Approaches to Investigating Postharvest Stress Physiology and the Biological Basis of Fruit Quality During Storage

“…The main parameters used to monitor the metabolic responses are based on the measurement of ethanol production by the fruit and/or the chlorophyll fluorescence (Schouten et al, 1997;Prange et al, 2002Prange et al, , 2003. If for apple (and a few other crops) storage, a constant decrease in oxygen concentration has been observed throughout the last recent decades, successful storage protocols for other fruit species are based on high (.10 kPa) CO 2 concentrations.…”