calcium chloride, citric acid or sodium pyrophosphate, it is perhaps simpler to use a hot water blanch, whereby the additives can be drip-fed from an auxiliary tank, at whatever rate is required Hot water blanchers should always be heated by a closed steam coil system, with live steam injection used only for boosting the blanching water to operating temperature. The liquor should not be recirculated through the additive make-up pans but allowed to over-flow to waste to avoid excessive foaming created by released starch. The blancher water should be changed at least once a day -depending on build up of excess starch The adequacy of the blanch is constantly checked by the peroxidase test. One of the purposes of blanching is to inactivate the surface enzymes the cut vegetable and, by using an indicator solution of Guaiacol and hydrogen peroxide on a sample of blanched vegetable, this can be gauged and, as long as negative peroxidase conditions are shown, blancher dwell times and temperatures are adequate. If the blanched dice discolour, turning brown when immersed in the guaiacol solution for less than one minute it is an indication of positive peroxidase, arising from underblanching. If no colour contrast develops within the minute, then peroxidase is negative and blanching conditions are adequate Underblanched potato shows up immediately the product dries, and his is manifested by the white, chalky appearance of the dice half-way hrough the drying cycle On leaving the blancher, the dice should be sprayed with fine jets of old water, again for the purpose of removing starch, then dewatered DRYING Suitable dryers for potato dice are (b)the through-conveyor band c)stove or throug With all types of dryer finishing is usually carried out in bin dryers Drying temperatures and times will vary according to the type of dryer used but typical'wet' inlet temperatures for an efficient 3-heat zone conveyor band dryer would be Outlet temperature would be65℃·71“ with efficient evaporative conditions. Finishing temperatures in bins range from 57"C to 60C Sizing and selection After drying, the dice are conveyed to a vibratory screen with an adequate sieving area and the 9.5mm dice or half dice are usually screenedcalcium chloride, citric acid or sodium pyrophosphate, it is perhaps simpler to use a hot water blanch, whereby the additives can be drip-fed from an auxiliary tank, at whatever rate is required. Hot water blanchers should always be heated by a closed steam coil system, with live steam injection used only for boosting the blanching water to operating temperature. The liquor should not be recirculated through the additive make-up pans but allowed to over-flow to waste to avoid excessive foaming created by released starch. The blancher water should be changed at least once a day - depending on build up of excess starch. The adequacy of the blanch is constantly checked by the peroxidase test. One of the purposes of blanching is to inactivate the surface enzymes of the cut vegetable and, by using an indicator solution of Guaiacol and hydrogen peroxide on a sample of blanched vegetable, this can be gauged and, as long as negative peroxidase conditions are shown, blancher dwell times and temperatures are adequate. If the blanched dice discolour, turning brown when immersed in the Guaiacol solution for less than one minute, it is an indication of positive peroxidase, arising from underblanching. If no colour contrast develops within the minute, then peroxidase is negative and blanching conditions are adequate. Underblanched potato shows up immediately the product dries, and this is manifested by the white, chalky appearance of the dice half-way through the drying cycle. On leaving the blancher, the dice should be sprayed with fine jets of cold water, again for the purpose of removing starch, then dewatered. DRYING Suitable dryers for potato dice are (a) the tunnel dryer @) the through-conveyor band (c) stove or through-flow tray dryer. With all types of dryer, finishing is usually carried out in bin dryers. Drying temperatures and times will vary according to the type of dryer used but typical 'wet' inlet temperatures for an efficient 3-heat zone conveyor band dryer would be: Zone1 107°C Zone2 99°C Zone3 85°C Outlet temperature would be 65°C - 71°C with efficient evaporative conditions. Finishing temperatures in bins range from 57'C to 60°C. Sizing and Selection After drying, the dice are conveyed to a vibratory screen with an adequate sieving area and the 9.5mm dice or half dice are usually screened I19