Mealiness assessment in apples and peaches using MRI techniques

Abstract

Mealiness (woolliness in peaches) is a negative attribute of sensory texture that combines the sensation of a desegregated tissue with the sensation of lack of juiciness. In this study, 24 apples cv. Top Red and 8 peaches cv. Maycrest, submitted to 3 and 2 different storage conditions respectively have been tested by mechanical and MRI techniques to assess mealiness. With this study, the results obtained on apples in a previous work have been validated using mathematical features from the histograms of the T2 maps: more skewed and the presence of a tail in mealy apples, similar to internal breakdown. In peaches, MRI techniques can also be used to identify woolly fruits. Not all the changes found in the histograms of woolly peaches are similar from those observed in mealy apples pointing to a different underlying physiological change in both disorders.

Prospects for the rapid detection of mealiness in apples by nondestructive NMR relaxometry

“…As with the nonspatially resolved relaxation data, it was found that the T 2 decreased with increasing mealiness and that at a certain point a broad change in the histogram shape was observed and corresponds to a signifícant increase in the standard deviation of the T 2 valúes within the apple. These MRI features therefore agreed with expectations on the basis of previous research work [1,2]. It is interesting to note that the T 2 map of apple CO-25 also features a tailed T 2 histogram and this apple also showed an abnormal variability in texture reference valúes.…”

“…Following previous research work [2] these data were used to calcúlate the following subsidiary parameters: The average, standard deviation, máximum and minimum T 2 valúes were calculated from the global T 2 maps (disregarding those pixels corresponding to the background or the core). The T 2 histograms were used to derive the lower quartile (T 2 lower limit containing 25% of pixels of the histogram), upper quartile (T 2 upper limit containing 25% of pixels of the histogram), T 2 mode (most frequent valúes), mode height (number of pixels with T 2 valué equal to the mode), interquartile range (difference between upper and lower quartiles), first shape coefficient (mode height/interquartile range), and second shape coefficient (0.5 times the number of pixels of the histogram/interquartile range).…”

“…In this paper we focus on the internal quality of apples and explore whether there is a significant correlation between the water protón transverse relaxation behavior and quality factors such as mealiness. Preliminary reports by Barreiro et al in 1999 and [1,2] succeeded in establishing a correlation between mealiness and changes in the spatially resolved T 2 maps in apples derived from sequences of 20 spin-echo images. Unfortunately, acquiring 20 images of each apple is quite impractical for the purpose of sorting apples on the basis of their mealiness so, in this paper, we explore whether nonspatially resolved relaxation measurements can be correlated with spatially resolved relaxation time distributions and mealiness.…”

Application of Low-Field Nuclear Magnetic Resonance and Proton Magnetic Resonance Imaging in Evaluation of ‘Jinxiu' Yellow Peach's Storage Suitability

“…NMR technology can provide better images of the internal structure of intact fruits and vegetables, and thus, it is suitable for detecting internal defects and quality issues such as decay and maturity (Barreiro et al, 2000) (Barreiro et al, 2004). 1 H-MRI technology can stimulate the RF-absorbing ability of fruits and vegetables as they have a multitude of proton-containing species .…”

A mathematical model for the development of mealiness in apples

“…Apart from the storage conditions, harvesting date and fruit size also influence the development of mealiness. Apples of larger size or of late harvest are more susceptible to mealiness (Barreiro et al, 2000;De Smedt, 2000). Hatfield and Knee (1988) and De Smedt et al (1998) concluded that the cells in mealy apples become more rounded, and, as a consequence, the amount of apoplast is larger in mealy apples than in fresh apples.…”