Granule‐assisted dishwashing improves cleanliness

Abstract

The cleanliness of plates and dishes washed in two different types of machines was investigated. Both machines were one‐tank dishwashers; one of them used water and detergent, the other used plastic granules, water and detergent as the cleaning medium. The mechanical effect of plastic granules, water and detergent cleaned the dishes better than water and detergent alone. For easily removed soil, as characterized in the international standards ANSI/NSF 3 and DIN 10512, both dishwashing machines resulted in clean dishes. Dishes covered with a more adhesive soil were clean only after washing in the granule‐assisted washer. The importance of cleaning plates and dishes, in order to avoid cross‐contamination and the spread of infection, is discussed.

Efficiency of manual dishwashing conditions on bacterial survival on eating utensils

“…The findings of this study are supported by various researchers who reported on the effectiveness of manual washing on the elimination of foodborne bacteria such as Salmonella spp., E. coli, Staphylococcus aureus, Campylobacter spp., and Enterococcus faecium (Johansson, Ståhl Wernersson, & Håkanson, 2005;Kusumaningrum et al, 2002;Mattick et al, 2003b;Ståhl Wernersson et al, 2004a, 2004b. These reports stated that the bacterial viability decreased with increasing air-drying time, washing temperature, washing time, and the choice of detergent.…”

“…This time/temperature relationship is measured in Heat Unit Equivalents (HUEs). To fulfill this ANSI/NSF standard, Ståhl Wernersson, Johansson, and Håkanson (2004b) reported that the removal of all visible soil and detergent from utensils, and >3600 HUEs must be achieved in washing tests using Mycobacterium phlei in milk and in culture broth. HUE testing is a method of ascertaining the effect of the cumulative killing factors applied to dish surfaces from time and temperature exposure in dishwashers.…”

Cross-contamination in dishwashers

“…8,14 In test soil C, the bacteria were moved from the metal test plates to the wash-water in the dishwater tank of the machine. 15 Wash-water samples from other dishwashing machines in hospital kitchens and restaurant kitchens have shown bacterial concentrations in the order of 10 3 -10 4 cfu/mL. 16 From the experiment with test soil C, the result showed that no bacteria remained on the metal test plates after a normal dishwashing process.…”

“…Test soil B was more difficult and demanded a larger flux of water in the cleaning process, which is obvious from our results ( Figure 4). 14,15 In the professional kitchen the soil is more Figure 5 Porcelain plates with soil residues (test soils I, II, III) after a normal dishwashing process. adhesive as in test soils I, II and III.…”

“…3,7,8,17 The thermal resistance test verifies that E. faecium can survive at much higher temperatures than is achieved in dishwashers. 3,7,15 Several other types of bacteria survive the temperatures produced by standard dishwashers and could cause serious infections in hospitals. 1,14,17 Another risk is cross-contamination from washwater to crockery.…”