Chlordioxid zur Reduktion von humanpathogenen Mikroorganismen bei der Salatwäsche

Der Markt für abgepackte verzehrfertige Frischsalate ist in den vergangenen Jahren stark gewachsen. Für die Herstellung von mikrobiologisch unbedenklichen Produkten wurde der Zusatz von Chlordioxid (ClO2) zum Waschwasser auf sein Potenzial zur Minimierung relevanter humanpathogener Mikroorganismen getestet. Dabei wurden auch wichtige Parameter der Produktqualität, wie z. B. Farbe und Inhaltsstoffe, berücksichtigt. Eine ClO2-Behandlung ermöglicht es, die Konzentration von Mikroorganismen im Waschwasser um 5 bis 6 log-Einheiten zu reduzieren, abhängig vom chemischen Sauerstoffbedarf (CSB-Wert). Farbe und Vitamin-C-Gehalt der Salatblätter werden von der Behandlung nicht beeinflusst. Demnach ist ClO2 zur Hygienisierung von Salatwaschwasser geeignet.During recent years, the consumption of prepackaged readyto- eat salads has strongly increased. To facilitate the production of microbiological safe fresh-cut products, the potential of chlorine dioxide for decontamination of iceberg lettuce during washing and its effects on external and internal quality parameters of the produce were investigated. ClO2 application results in 5 to 6 log reduction of microorganisms in the washing water, depending on its chemical oxygen demand (COD). Colour parameters and vitamin C content of leaves were not affected by chlorine dioxide washing. Therefore, chlorine dioxide is an appropriate sanitizer to minimize human pathogens in lettuce washing water

Effects of Pre-Processing Short-Term Hot-Water Treatments on Quality and Shelf Life of Fresh-Cut Apple Slices

Processing, especially cutting, reduces the shelf life of fruits. In practice, fresh-cut fruit salads are, therefore, often sold immersed in sugar syrups to increase shelf life. Pre-processing short-term hot-water treatments (sHWT) may further extend the shelf life of fresh-cuts by effectively reducing microbial contaminations before cutting. In this study, fresh-cut ‘Braeburn’ apples, a major component of fruit salads, were short-term (30 s) hot water-treated (55 °C or 65 °C), partially treated with a commercial anti-browning solution (ascorbic/citric acid) after cutting and, thereafter, stored immersed in sugar syrup. To, for the first time, comprehensively and comparatively evaluate the currently unexplored positive or negative effects of these treatments on fruit quality and shelf life, relevant parameters were analyzed at defined intervals during storage at 4 °C for up to 13 days. Compared to acid pre-treated controls, sHWT significantly reduced the microbial loads of apple slices but did not affect their quality during the 5 day-standard shelf life period of fresh-cuts. Yeasts were most critical for shelf life of fresh-cut apples immersed in sugar syrup. The combination of sHWT and post-processing acid treatment did not further improve quality or extend shelf life. Although sHWT could not extend potential maximum shelf life beyond 10 d, results highlighted the potentials of this technique to replace pre-processing chemical treatments and, thus, to save valuable resources

Effects of Pre-Processing Hot-Water Treatment on Aroma Relevant VOCs of Fresh-Cut Apple Slices Stored in Sugar Syrup

In practice, fresh-cut fruit and fruit salads are currently stored submerged in sugar syrup (approx. 20%) to prevent browning, to slow down physiological processes and to extend shelf life. To minimize browning and microbial spoilage, slices may also be dipped in a citric acid/ascorbic acid solution for 5 min before storage in sugar syrup. To prevent the use of chemicals in organic production, short-term (30 s) hot-water treatment (sHWT) may be an alternative for gentle sanitation. Currently, profound knowledge on the impact of both sugar solution and sHWT on aroma and physiological properties of immersed fresh-cuts is lacking. Aroma is a very important aspect of fruit quality and generated by a great variety of volatile organic compounds (VOCs). Thus, potential interactive effects of sHWT and sugar syrup storage on quality of fresh-cut apple slices were evaluated, focusing on processing-induced changes in VOCs profiles. Intact ’Braeburn’ apples were sHW-treated at 55 °C and 65 °C for 30 s, sliced, partially treated with a commercial ascorbic/citric acid solution and slices stored in sugar syrup at 4 °C up to 13 days. Volatile emission, respiration and ethylene release were measured on storage days 5, 10 and 13. The impact of sHWT on VOCs was low while immersion and storage in sugar syrup had a much higher influence on aroma. sHWT did not negatively affect aroma quality of products and may replace acid dipping

Influence of Washing Method on the Quality of Prepacked Iceberg Lettuce

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 7 (2005): Influence of Washing Method on the Quality of Prepacked Iceberg Lettuce by Karin Hassenberg and Christine Idle

Chlordioxid zur Reduktion von humanpathogenen Mikroorganismen bei der Salatwäsche

During recent years, the consumption of prepackaged ready-to-eat salads has strongly increased. To facilitate the production of microbiological safe fresh-cut products, the potential of chlorine dioxide for decontamination of iceberg lettuce during washing and its effects on external and internal quality parameters of the produce were investigated. ClO2 application results in 5 to 6 log reduction of microorganisms in the washing water, depending on its chemical oxygen demand (COD). Colour parameters and vitamin C content of leaves were not affected by chlorine dioxide washing. Therefore, chlorine dioxide is an appropriate sanitizer to minimize human pathogens in lettuce washing water

Effect of Chlorine Dioxide Treatment on Human Pathogens on Iceberg Lettuce

In the vegetable processing industry, the application of chlorine dioxide (ClO2) as a disinfectant solved in washing water to eliminate undesirable microorganisms harmful to consumers’ health and the shelf life of produce has been discussed for years. The disinfection efficacy depends on various factors, e.g., the location of microorganisms and the organic load of the washing water. The present study analyzed the sanitation efficacy of various concentrations of water-solved ClO2 (cClO2: 20 and 30 mg L−1) on Escherichia coli (1.1 × 104 cfu mL−1), Salmonella enterica (2.0 × 104 cfu mL−1) and Listeria monocytogenes (1.7 × 105 cfu mL−1) loads, located on the leaf surface of iceberg lettuce assigned for fresh-cut salads. In addition, it examined the potential of ClO2 to prevent the cross-contamination of these microbes in lettuce washing water containing a chemical oxygen demand (COD) content of 350 mg L−1 after practice-relevant washing times of 1 and 2 min. On iceberg leaves, washing with 30 mg L−1 ClO2 pronouncedly (1 log) reduced loads of E. coli and S. enterica, while it only insignificantly (<0.5 × log) diminished the loads of L. monocytogenes, irrespective of the ClO2 concentration used. Although the sanitation efficacy of ClO2 washing was only limited, the addition of ClO2 to the washing water avoided cross-contamination even at high organic loads. Thus, the application of ClO2 to the lettuce washing water can improve product quality and consumer safety