Fresh tomato fruit at the mature-green stage was obtained from a commercial supplier in Saltillo, Coahuila, México. Fruits were selected by visual uniformity in size, color (Breaking-Stage 2, Color 2) (United States Department of Agriculture, 2005), and absence of microorganisms. Before coating application, fruits were washed with a solution of sodium hypochlorite (2%) for 2 min, and air dried at room temperature.

Aqueous dispersions were prepared by dissolving protein (1.28% w/v) in distilled water at room temperature (25°C ± 2°C) for 10 min. Afterward, the solution was heated at 80°C ± 2°C for 30 min, then glycerol (0.5% v/v) and candelilla wax (0.3% w/v) were added. A homogenization at 15,000 rpm for 12 min was performed. Cooling was achieved by placing the emulsions at room temperature to bring them to less than 40°C. A vacuum pump was used to eliminate non-condensable gases from dispersions and the pH of solutions was maintained at 5.6 value. Coating treatment (CC) was selected according to preliminary experiments. An additional treatment was evaluated by adding polyphenols from a tarbush aqueous extract at a concentration of 500 ppm (CP).

Seventy fruits were immersed in each treatment (CC and CP) solution for 10 s, while control fruit (SC) were dipped in distilled water. Fruits were submerged twice once the first layer was air-dried. After the second dry layer, fruits were placed in trays and stored at room temperature (27°C ± 2°C) for 10 days. Data were recorded on the initial day (day 0) and at 2-day intervals.

During the storage period, seven parameters were monitored during tomato shelf life with sampling every 48 h. Weight loss. Weight was gravimetrically measured with an analytical balance (Explorer, OHAUS). The difference between the initial and final point was considered as total weight loss during storage calculated as percentages on a fresh basis [8]. Fruit firmness. The firmness of tomatoes was measured with a Humboldt universal penetrometer (model H-1200, Chicago, IL) by measurement penetration (mm), where samples were placed in such a way for equatorial penetration. Total soluble solids (TSS), titratable acidity, and pH. TSS was determined by method 932.12 of A.O.A.C. (AOAC, 1990) using a densimeter (DMA 35N, V2.014, Anton Paar). Changes in pH values were obtained using a pH meter (Orion model-420, Boston, MA) [9]. Changes in acidity (%) were determined by the (AOAC, 1990) 939.05 method. A sample of tomato pulp was diluted with distilled water 1:1. It was titrated with a 0.1 N NaOH titrated solution, and then 10 mL of the sample were transferred to a flask with 4 drops of phenolphthalein indicator and the sample was titrated until a pink color was obtained for 1 min. Color. The color was determined using the 3nh colorimeter model (NR110), and values were recorded as L, a, and hue angle (°Hue). Chlorophyll and lycopene content: chlorophyll and lycopene content was measured following the methodologies reported by Dere et al. [10] and Javanmardi and Kubota [11]. Appearance changes were evaluated using a photographic camera (14 Mpix Lumix, Panasonic DMC-FH6) every 2 days of storage.

Tomatoes were disinfected by submerging them for 1 min in sodium hypochlorite at 2% (v/v) and then dried completely. A cross-shaped cut of a length of 5 mm was made on each sample. Samples were inoculated with a spore solution of 1 × 10⁶ cells/mL. Coated samples were stored at room temperature 27°C ± 2°C for 6 days. Mold growth was checked every day by measuring the diameter of material decay from the cutting site. Results were provided in millimeters.

Agilent Technologies Gas Chromatograph 7820 was used with an injection volume of 1 mL with a plastic syringe and 25 × 1 needle to both samples, a run time of 3.5 min [CO₂ elutes at 1.1 min, and ethylene (C₂H₄) at 1.9 min]. A packed Column HayeSep Q 100/120 mesh, thermal conductivity detector (TCD) for CO₂ and flame ionization detector (FID) for C₂H₄ were employed.

Sensory evaluation was performed only with treatments without polyphenol compounds in addition to the control. Fruit quality was estimated by evaluating attributes of global appearance, color, smell, flavor, texture, and global acceptance on the initial day, day 5, and day 10 of storage. A trained panel of 12 judges with ages ranging from 20 years to 26 years was used. Panelists were asked to score differences between samples where 1 represented extreme dislike, 2 unpleasant, 3 neither pleasant nor unpleasant, 4 pleasant, and 5 excellent for five variables (color, texture, flavor, smell, and overall acceptability).

The experiment was established under a completely randomized design (CRD) with three replications. The data were subjected to analysis of variance (ANOVA) using the computer software STATISTICA 7.0; when it was needed, the Tukey multiple comparison test was used to compare differences between treatment means at the 95% confidence level.

The SC treatment showed the best result against the phytopathogen Rhizopus stolonifer with a growth of 38.22 mm of radial growth, while the CC and CP treatments showed growth of 49.25 mm and 40.72 mm, respectively. By observing the fruits internally, it was realized that in the SC treatment, the microorganism managed to reach the interior, causing liquefaction of the soft tissue, as is shown in Figure 5, allegedly caused by the generation of enzymes that degraded the internal fruit walls. This was not observed in CC and CP treatments, having a positive effect when coatings were applied.

All samples increased their respiration rate during ripening, which can be corroborated with the data shown above, showing that metabolic activity continues even with the application of the coating. After 10 days of storage, the CC treatment showed the lowest CO₂ production value (17.21 mL kg^–1 h^–1) compared to the control treatment (19.03 mL kg^–1 h^–1), indicating that coating may have modified the internal atmosphere of the fruit, decreasing the respiration rate. The same behavior is observed with C₂H₄ production. The lowest value found was with the CC treatment (4.66 L C₂H₄ kg^–1 h^–1), compared to the SC and CP treatment (7.07 L C₂H₄ kg^–1 h^–1 and 6.13 L C₂H₄ kg^–1 h^–1, respectively) at day 6 of evaluation.

The reduction in C₂H₄ production results in a delay in the ripening processes. A similar behavior was observed by Ruelas-Chacon et al. [13], where the highest CO₂ value was (10.7 mL kg^–1 h^–1), similar to that obtained in this research, it should be noted that the coating forming material employed by these authors was Guar gum.

Sensory evaluation was performed only for SC (C) and CC (T) treatments, the CP treatment was not evaluated in this trial due to previous results where the best result was obtained with the CC treatment.

The test revealed differences between the evaluated treatments. No significant differences were found on the initial day, but as the storage time increased, significant differences were found by the panelists. The results are shown in Figure 6, where the scores given by the panelists to all the attributes were between 3 and 4, which is interpreted as “good” and “very good”, respectively. It can be observed that there is a similar preference in all treatments in the case of odor, which indicates that there are no perceivable differences in this parameter. Likewise, we can observe that as the days of storage increased, appearance and overall acceptance by the control and treated tomatoes were affected after 10 days under the test conditions. The rest of the analysis shows similar results between units with treatments and days of storage.

Sensorial results suggest that the protein coating can be used to extend the shelf-life and improve tomato quality during storage at room temperature (22°C ± 2°C). C and T saladette tomatoes were not sensory analyzed after 10 days of storage based on the microbiological results.