Magnetic resonance imaging provides spatial resolution of Chilling Injury in Micro-Tom tomato (Solanum lycopersicum L.) fruit

Magnetic resonance imaging (MRI) was used to monitor internal changes in harvested tomato (Solanum lycopersicum L. cv. Micro-Tom) fruit. Measurements of ethylene evolution, respiration, and ion leakage indicated that the fruit developed chilling injury (CI) after storage at 0 °C. Unlike these measurements, MRI provided spatially resolved data. The apparent diffusion coefficient (ADC), which is an indication of water mobility in tissues, was calculated from MRIs of the different parts of the fruit. Storage for 1 or 2 weeks at 0 °C caused no difference in the ADCs (D-values) in the pericarp, but it did lead to higher values in the inner tissues i.e., the columella and locular region compared to non-chilled fruit (P < 0.05). Changes in inner fruit D-values after 1 and 2 weeks of chilling at 0 °C were similar to changes in respiration, ethylene production and ion leakage which increased (P < 0.05) compared to the non-chilled controls. Most CI studies of tomato fruit used pericarp tissue. Our data indicate that columella tissue changes occur in response to chilling injury in tomato fruit and suggest that more caution is needed when interpreting data from experiments commonly used to study this phenomenon.     

Quality and internal characteristics of Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua) treated with different kinds of coatings during storage

We studied the quality and internal changes in Huanghua pears (Pyrus pyrifolia Nakai, cv. Huanghua) coated with shellac, Semperfresh™ (sucrose polyester base coating), and carboxymethyl chitosan (CMC) during cold storage (4 °C). The changes in respiration rate, weight loss, cell membrane permeability and texture profile analysis (TPA) such as hardness, brittleness and chewiness were recorded periodically for up to 60 days after harvest to compare the effects of the applied coatings. Magnetic resonance (MR) imaging was used to inspect the internal characteristics of pears after storage. The soluble solids contents (SSCs), titratable acidity (TA), ascorbic acid concentration, and taste scores were also measured. Our data suggest that shellac coating was more effective in reducing the respiration rate and weight loss and in maintaining the quality of pears than Semperfresh and CMC coatings.     

Analysis of genotypic variation of sugar and acid contents in peaches and nectarines through the Principle Component Analysis

Genotypic variations and correlations were estimated for sugar and acid contents on afresh flesh weight basis in peach and nectarine genotypes derived from a clone of a wild peach (Prunus davidiana) by three generations of crosses with commercial nectarine varieties. 107genotypes were studied in Avignon (France), 40 in Gotheron (France), and 18 of them were common to both locations. Considerable variations in sugar and acid contents were found among genotypes in both locations. Though location significantly affected sucrose, sorbitol and acid contents of the18 common genotypes, principal component analysis (PCA) indicated that genotypic correlations among sugar and acid contents were stable in both locations. Almost all sugars and acids analysed exhibited positive loadings for the first principal component (PC). Variations of dry matter content among genotypes only partially explained this general trend as shown by the PCA on a dry flesh weight basis. Glucose and fructose contents were closely correlated and were similar in amount inmost genotypes, while fructose content was lower than glucose content in about 12% of the genotypes. A positive but loose relationship was found between malic and citric acid contents in both locations. Likewise, sucrose, sorbitol and quinic acid contents were positively associated. The first PC could be used as a general flavour component. In addition, three groups of closely associated variables (fructose and glucose; malic and citric acids; sucrose, sorbitol and quinic acid) were detected through PCA. This revised version was published online in July 2006 with corrections to the Cover Date.