Application of Browning Inhibitors to Cut Apple and Potato by Vacuum and Pressure Infiltration

Vacuum and pressure infiltration were investigated as means of applying ascorbatc- or erythorbate-based enzymatic browning inhibitors to apple and potato cut surfaces. Apple plugs infiltrated at 34 kPa pressure showed more uniform uptake of treatment solution and less extensive water-logging than plugs vacuum-infiltrated at 169–980 mB. Delicious and Winesap plugs and dice gained 3–7 days of storage life at 4°C when treated by pressure infiltration, compared to dipping. However, infiltrated dice required dewatering by centrifugation or partial dehydration to prevent water-logging. Pressure infiltration at 108 kPa extended the life of potato plugs by 2–4 days, compared to dipping, but was ineffective with potato dice.     

DSC Study of the Thermophysical Properties of Aqueous Liquid and Semi-Liquid Foodstuffs at Freezing Temperatures

Differential scanning calorimetry (DSC) was used to study the thermophysical properties and phenomena occurring in aqueous liquid and semi-liquid foodstuffs at freezing temperatures. Investigations were carried out with fruit juice concentrates, sauces, soups and spinach purée. The phase transitions such as glass transition, irruptive recrys-talization (devitrification), ante-melting transition and melting are faithfully reflected by DSC curves. Besides depending on the temperature, these phenomena depend primarily on the mass fraction of water, and the fraction of other components in the dispersion system. The temperatures of phase transitions (solidification and melting), the latent heat of fusion (ΔH) and specific heat also depend on the same factors.     

INFLUENCE OF WASHING TREATMENT ON NATIVE MICROFLORA AND ESCHERICHIA COLI POPULATION OF INOCULATED CANTALOUPES

The influence of chlorine or hydrogen peroxide treatment on populations of Escherichia coli 25922 on the external surface of inoculated cantaloupe was investigated. Surface treatment with 70% EtOH, followed by immersion in 10⁸ CFU/mL E. coli inoculum deposited an average of 4.4 log₁₀CFU/cm² cell population on the cantaloupe surface. The efficncy of washing inoculated cantaloupe was dependent on storage interval between inoculation and treatment. Dipping the cantaloupes in solutions containing 1000 mg/L chlorine or 5% peroxide for 5 min, within 24 h of inoculation, caused a 2 log₁₀ CFU/cm² reduction of the indigenous surface microflora and a 3–4.0 log₁₀ CFU/cm² reduction in E. coli. The efficacy was less when the interval between inoculation and treatment exceeded 24 h. Chlorine appeared in be a better antimicrobial agent than hydrogen peroxide against F. coli ATCC 25922 inoculated on cantaloupe surfaces while hydrogen peroxide was better in reducing surface microflora of cantaloupe.     

STABILITY OF ANTHOCYANINS, PHENOLS AND FREE RADICAL SCAVENGING ACTIVITY THROUGH SUGAR ADDITION DURING FROZEN STORAGE OF BLACKBERRIES

Influence of sugar and mixtures of sugar on color retention of two varieties of blackberries, Thornfree and Cacanska bestrna, were investigated during storage at − 18C for 12 months. After harvest, blackberries were coated with sugars (sucrose, fructose and glucose) and different sugar (sucrose  +  fructose  +  glucose, fructose  +  glucose, fructose  +  sucrose) mixtures. Anthocynin content, total phenol content and free radical scavenging activity of prepared samples were evaluated. Ratio of fruit : sugar was 1:1. The highest anthocyanin retention was in blackberry samples with glucose addition and the lowest in samples with sucrose addition, in both cultivars. Blackberry samples with sucrose addition had even lower retention than samples without sugar addition. Samples with an addition of other sugars had higher retention of anthocyanin than samples stored without sugars.

PRACTICAL APPLICATION

Possibility of phenols retention of blackberries due to sugar addition, during cold storage was investigated. Results showed that glucose had the most positive effect on anthocyanins retention as well as total phenolic compounds content. For that reason, certain amount of sucrose in fruit preserves can be replaced by addition of glucose, and for that reason retention of phenolic compounds can be higher and, as could be expected, more effective against oxidative stress in human body due to intake of product formulation with glucose.