Roma Tomatoes Research Articles

Effects of Exogenous Calcium Salt Treatments on Inhibiting Irradiation‐Induced Softening in Diced Roma Tomatoes

ABSTRACT: Freshly diced tomatoes were dipped into either 0.2% or 1% calcium chloride or 2% calcium lactate solution and exposed to γ‐irradiation at 1.25 kGy. With increasing levels of calcium, firmness was enhanced, water‐soluble pectin was decreased, and oxalate‐soluble pectin was increased. Irradiation decreased instrumental firmness in all samples; however, the 1% calcium chloride and 2% calcium lactate‐dipped samples remained firmer than the water‐dipped control. Irradiation alone did not have a significant impact on pectic substances. Trained sensory panelists did not detect a significant loss of firmness due to irradiation in the calcified tomatoes, but some judges detected a change in flavor following the calcium dips.

The effects of gamma irradiation on the microbiological, physical and sensory qualities of diced tomatoes

Diced Roma tomatoes were treated with gamma irradiation and evaluated for changes in microbial, physical, chemical and sensory properties. Dosages for Trial 1 were 0.0, 0.39, 0.56 and 1.82 kGy and in Trial 2, 0.0, 0.50, 1.24 and 3.70 kGy. Irradiation at 3.70 kGy resulted in no aerobic populations through day 12 and significantly fewer colonies through day 15 whereas yeast and mold populations experienced a 2 log reduction through day 12. Color, titratable acidity, and °Brix were not significantly affected by irradiation. Tissue firmness decreased with increasing dose but not with storage time. Treatment with 3.7 kGy decreased firmness by 50% and 20% with 0.5 kGy, however, the reduced firmness induced by 0.50 kGy was undetected by a 9 member trained sensory panel. A significant ( p⩽0.05) inverse correlation between changes in texture and water-soluble pectin (WSP) was determined while total pectin remained relatively constant and oxalate soluble pectin content decreased slightly with irradiation dose. The significant inverse correlation between the loss of firmness and WSP indicates that the changes in WSP play an important role in the tissue softening of tomatoes, This study indicates that irradiation at 0.5 kGy can reduce microbial counts substantially to improve microbial shelf life without adverse effects on sensory qualities.

MRI METHOD TO EVALUATE INTERNAL STRUCTURAL CHANGES OF TOMATO DURING COMPRESSION

ABSTRACTThe effects of compression on the structure of red Roma tomato (Lycopersicon esculentum) were observed using magnetic resonance imaging (MRI). Images were acquired at six strain levels: 0%, 3%, 6%, 20%, 25% and no load sequentially for each of the replicates. The MR images revealed internal structural changes as the strain level increased; these changes were characterized by three displacement parameters: buckling angle (α), flattening angle (β) and columella position (hc). The relative change of these parameters as a function of strain was evaluated by analysis of variance (ANOVA), which showed that the difference in the means was significant at the 0.05 level. In the post hoc analysis, structural changes at the low strains of 3% and 6% were different than the structural changes at the higher strains of 20% and 25%. The columella position showed significant recovery after the load was released. In addition to structural changes, the NMR signal intensity changed as a result of the compression. In particular, signal intensity from the columella region and upper radial arm increased with strain level. However, further studies are required to analyze these changes statistically.