Deluge Blanchers
VOL. 19 NO.8
The large french fry potato belt blanchers manufactured by this company were developed in the 1970's and have been refined over the past twenty years. Widths are normally ten to twelve feet, with the longest over one hundred feet. Units manufactured after the mid 1980's are deluge water blanchers, with ten gallons of water applied to each square foot of product each minute. A twelve foot wide, one hundred foot deluge length blancher will have a total recirculation rate of approximately twelve thousand gallons per minute. Overhead spray pipes with nozzles are used to distribute the water to the blanch area. Most deluge blanchers can either be operated with the product immersed in water, or in straight deluge with the water level just below the product carrying belt. Some blanchers have the ability to steam blanch. While a few of the blanchers utilize heavy duty wire mesh with side chains, most use hump belt panels carried by Gem stainless steel chain with stellite pins and bushings. Normal design provides for twelve inch product depth.
For most vegetables, blanching sterilizes the product and kills the enzymes. In addition, for potatoes, blanching has a significant affect on finished product texture and leaches sugars. Sugar content increases in spring when the potato is getting ready to start growing. During this period, if some sugar is not removed, many potato varieties at most locations, will result in finished product that has too dark a color. The blanching process literally washes the excess sugar out of the cut potato strips. Some of the water in the blancher will have to be replaced with fresh water to avoid loss of leaching ability caused by potato solids build-up in the blanching water. As long as the water is not saturated with sugar, any contact with water will leach sugar out of the potato. Even after almost twenty years of deluge blanching, a few french fry potato processing lines still use deluge blanching's predecessor, the auger blancher.
Since Gem manufactures a higher number of deluge blanchers than auger blanchers, one would expect this company to be partial to deluge blanchers. Fortunately, this partiality is backed by theory and experience. With a deluge blancher, the product bed is uniform and water flow through the product is better controlled at a higher rate than is possible with an auger blancher. For leaching high sugar potatoes, deluge blanchers have normally out performed auger blanchers. Side by side operation of the two types of blanchers has proven that deluge blanching is able to cope with sugar content too high for adequate leaching by an auger blancher. Reduced potential for product breakage can also be an advantage for the deluge blancher. Large lines require more than one auger blancher to achieve necessary capacity, resulting in additional transfer points. One large belt blancher is still capable of handling full line capacity even with the long blanch times required for potatoes with high sugar content. However, even with the additional transfer points, if an auger blancher is well designed and operated at design capacity, the amount of breakage is not prohibitive. Unfortunately, sooner or later, most auger blanchers end up operating above design capacity, thus causing too much breakage.