1% Calcium Chloride Treatment in Combination with Gamma Irradiation Improves Microbial And Physicochemical Properties of Diced Tomatoes

Abstract

The purpose of this study was to determine the effect of a combination of a 1% calcium chloride dip with low dose irradiation on microbial populations, and biochemical and physical properties, of fresh diced tomatoes during a two-week storage period. Vine tomatoes at the light-red stage (trial 1) and Celebrity tomatoes at the table ripe stage (trial 2) were diced, dipped in 1% CaCl(2), and irradiated at 1 kGy from a Co(60) source. Tomatoes were also contaminated with cocktail of nalidixic-acid resistant Salmonella strains (S. Poona, S. Hartford, S. Gaminara, S. Michigan, and S. Montevideo) and subjected to gamma irradiation. Calcium treatment alone stimulated ethylene production in the diced tomatoes, whereas irradiation treatment alone suppressed ethylene production. The combination of calcium and irradiation treatments resulted in no change in ethylene production compared to the nontreated control, but respiration rate was suppressed by both irradiation and calcium treatment. The calcium dip was found to limit irradiation-induced loss of firmness. Irradiation, by itself and in combination with calcium treatment, resulted in a >3 log CFU/g decrease in total aerobic counts and psychrotrophs. Additionally, irradiation at 1.5 kGy eliminated > 3 log CFU/g of Salmonella organisms from tomatoes contaminated with Salmonella. Counts continued to decrease to an undetectable level over the 11 day storage period. The results indicate that the combination of calcium treatment and irradiation can reduce the risk of disease due to pathogenic organisms such as Salmonella and can eliminate the problem of softening induced by irradiation.

Microbial Quality and Safety of Fresh Produce

“…A dose of 2.0 kGy completely controlled the fungal and bacterial counts on carrot slices stored at 5°C for 2 weeks. The effect of a combination of a 1% calcium chloride dip with low-dose irradiation (1.5 kGy) on microbial populations was evaluated on fresh diced tomatoes during a two-week storage period (Prakash et al, 2007). The effect of a combination of a 1% calcium chloride dip with low-dose irradiation (1.5 kGy) on microbial populations was evaluated on fresh diced tomatoes during a two-week storage period (Prakash et al, 2007).…”

ELECTRON BEAM IRRADIATION ON NALIDIXIC ACID‐RESISTANT SALMONELLA MONTEVIDEO IN COOKED TOMATO PUREE OF VARIOUS pH VALUES

“…2004; Schmidt et al . 2006; Prakash et al . 2007) with no change in texture, color or sensory quality (Koorapati et al .…”

“…Stem scars were removed and the tomatoes were pureed for 30 s using a laboratory blender (Waring commercial model number S13L31, Torrington, CT). Preliminary studies showed interference of the native flora with the Salmonella inoculum; therefore, the tomato puree was autoclaved prior to inoculation (Prakash et al . 2007).…”

The Potential of Food Irradiation: Benefits and Limitations

“…For powdered dehydrated vegetables higher treatments (3-5 kGy) were suggested (Dong-Ho et al, 2002). Treatments for instance calcium chloride could decrease the effect of irradiation on fruit firmness (Prakash et al, 2007). Also, D10 values for various Salmonella strains in orange juice were between 0.6 and 0.8 KGy (Niemira & Lonczynski, 2006).…”