Quantitative nmr imaging of kiwifruit (actinidia deliciosa) during growth and ripening

Abstract

Quantitative 1H magnetic resonance (MR) imaging was used to determine relaxation changes (T1, T2‐CPMG) at regular intervals during growth and ripening of kiwifruit (Actinidia deliciosa var deliciosa). Temporal trends and differences between flesh, locule and core tissue were found for both relaxation parameters. However, no consistent associations were found between non‐destructive measurements and those for individual free sugars, soluble solids content (SSC) and macronutrients and micronutrients determined on dissected companion samples. Increases of 200% in total free sugar concentration in flesh and 68% in SSC accompanied starch hydrolysis after harvest. Despite the magnitude of these changes, relaxation times remained unaltered. These observations were repeated in a second investigation using A arguta fruit and T1, T2, T2‐CPMG and self‐diffusion image contrasts. Here, SSC increased 125% during a compressed 15‐day ripening period, while MR parameters like self‐diffusion declined only 7–14% from harvest values. T2‐CPMG relaxation was also investigated in aqueous solutions containing individual organic acids, sugars or pectate and juice from ripening fruit (4·7–15·5% SSC). Analysis of solutions and juices showed relaxation is indeed sensitive to increases in sugar composition but relatively insensitive to changes in organic acids and soluble pectin at concentrations normally found in fruit. Results imply that relaxation parameters determined from MR images may not be appreciably influenced by processes that cause solution composition to vary dramatically, even though these changes are reflected in the relaxation properties of the juice itself. Possible reasons for this are discussed with regard to the impact of cell structure and magnetic field strength on relaxation processes. © 1998 Society of Chemical Industry.

Moisture migration by magnetic resonance imaging during eggplant drying: a preliminary study

“…Other studies were performed on meat (Renou et al, 2003;Shaarani et al, 2006), fish and fruits (Clark et al, 1998). A review of MRI application to food products is reported by Schmidt et al (1996), Ruan & Chen (1998) and Marcone et al (2013).…”

Nuclear magnetic resonanceimaging of membrane permeability changes in plants during osmoticstress

“…Clark, Drummond & MacFall (1998)already showed that increases of 200% in free sugar concentrationsin kiwi fruit did not result in any changes in the observed relaxationtimes in ripening kiwifruit at a 2 T imaging system. Atthe lower magnetic field strength of 0·5 T inour experiments, the influence of sugars on relaxation times dueto proton exchange is expected to be even less than at high magneticfield strengths; therefore a possible osmotic solute accumulationduring stress will not cause a significant change in the bulk relaxationproperties.…”

Longitudinal NMR parameter measurements of Japanese pear fruit during the growing process using a mobile magnetic resonance imaging system

“…There have been many studies of relaxation time measurements of fruits in different growth stages [32,33], in which it was also reported that the relaxation times lengthen with the growing term of the fruit. As far as we know, this study is the first to report relaxation times of identical growing fruits measured in situ during the growth stage.…”