The website has the complete lesson note for all the subjects in secondary school but this piece showcases the SS1 Catering Craft Practices Lesson Note on Defrosting. You can use the website search button to filter out the subject of interest to you.
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Defrosting
This is important as it helps equipment perform efficiently and prevents a potentially damaging build-up of ice. Presence of ice on the evaporator or internal surface indicates the need for urgent defrosting; if the equipment is designed to defrost automatically this also indicates a fault.
Automatic defrosting may lead to a temporary rise in air temperature, this normally will not put food at risk. For manual defrosting of chest freezers always follow the supplier’s instruction to obtain optimum performance.
Never use a hammer or any sharp instrument that could perforate cabinet lining. A plastic spatula can be used to remove stubborn ice.
Emergency Measure: – Signs of imminent breakdown include:
- Unusual noises
- Fluctuating temperatures
- Frequent stopping and starting of the compressor
- Excessive frost building-up
- Absence of normal frost
Prepare to call a competent refrigerator service engineer, but first check that:
- The power supply has not been accidentally switched off.
- The electrical circuit has not been broken by a blown fuse or the triggering of an automatic circuit breaker.
- There has been no unauthorized tampering with temperature control device
- Any temperature rise is not due solely to routine automatic defrosting, to the refrigerator door being left open, to over loading the equipment or to any blockage of internal passage of air.
- There is no blockage of air to the condenser of rubbish
Crates/Cartons: -If these are not present, keep the door of the defective cold cabinet closed as much as possible to retain cold air. Destroy any spoil food. Call the ‘service-engineer’. All types of refrigerators-walk-in, cabinet with or without forced air circulations should be monitored for efficiency. Maintenance and servicing should be carried out regularly by qualified personnel.
DISH-WASHER: – The effective operation of the dishwasher plays a critical role in food service sanitation by providing the operator with visibility clean, sanitized and attractive tableware. This helps to ensure that clean and attractive tableware is always available. Most machines clean in a four-step process.
Pre-wash Stage: – In the pre-wash chamber of dishwasher hot water sprays of around 450C remove most of the easy soil from the table-wear. This soil is usually greasy and can’t be removed effectively with cold water.
Wash Stage: – The heart of the dishwasher is the washing section. A solution of hot water of 550c and detergent is drawn into a powerful pump and then forced under pressure into pipes and either fixed or on conveyor belts. This solution is forced out of orifices in a heavy spray that has a flushing action, which first loosens the soil then it washes off. The wash water should be between 600c-650c.
Rinse Stage: – During this cycle, hot water at 650c-750c remove the detergent solution and any residual soils from the tableware. The action is similar to that described in the wash tank but the water here is without detergent.
Final Rinse Stage: – In the final stage, all trace of the wash solution is removed. Temperature of 820c should be used to sanitize the tableware. Fast surface drying will occur at this temperature.
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