Sanitation is a critical component in all ice machine technology. One of the newest approaches to achieving proper sanitation involves the antimicrobial AlphaSan®, which is being used by Manitowoc in certain plastic components of its ice machines. It is part of a line of sanitation products offered by the company.

“The importance of a clean ice machine can be measured in the amount of money spent to repair and clean the machine,” said Mike Rimrodt, Manitowoc product manager, who authored a white paper on the topic. “Microbial growth leading to biofilm slime is one of the leading causes of ice machine breakdown.”

He added that while technologies such as antimicrobial products are designed “to reduce the frequency and severity of cleaning, they do not eliminate the need for periodic overall cleaning and maintenance.”

Rimrodt pointed out that microbes, including bacteria and fungi, are found “on our hands, in the water we drink, and in the air we breathe.”

He continued: “A microbe’s primary goal in life is to find a surface rich in nutrients and attach to it. Once attached, they set up shop on the surface and begin to grow and divide over a period of weeks and months. A byproduct of this microbial growth on a surface is the production of exopolymers, commonly referred to as ‘slime’ throughout the industry.”

How It Works

“The goal of AlphaSan is to keep the plastic surfaces of an ice machine cleaner by reducing or delaying the formation of biofilm,” said Rimrodt.

The active ingredient is silver in the form of silver ions (Ag+), which are slowly released through an ion-exchange mechanism.

“When AlphaSan is compounded directly into a plastic part,” said Rimrodt, “a controlled release of silver ions from the surface is regulated to maintain an effective concentration at or near the surface of the plastic ice machine part.”

The product is said to protect against undesired discoloration of the plastic and is said to last the lifetime of the plastic part.


Rimrodt noted that three years of testing preceded the decision to introduce AlphaSan into Manitowoc ice machines. The process included application development, lab testing, life-cycle testing, and dealer surveys. AlphaSan was developed by Milliken Chemical of Spartanburg, S.C.

Various antimicrobials have been used in ice machine equipment for a number of years. “The concept of silver as an antimicrobial is not new to the ice machine industry,” noted Rimrodt.

“The largest hurdle to overcome when utilizing silver-based antimicrobials is the ability to provide a slow, controlled release of silver from the host matrix. The failure to control this mechanism of release from the host matrix results in severe discoloration of the treated parts.”

He noted that discoloration resulted from the antimicrobial silver ions forming a variety of colored salts and metal complexes.

“In addition to adversely affecting the color of the plastic, the amount of bio-available silver is significantly decreased, resulting in limited durability.”

Because of this, “AlphaSan was specifically engineered to combine the outstanding antimicrobial performance of silver without suffering the undesired plastic discoloration,” said Rimrodt.


Another test involved the effects the technology may have on the taste of the ice.

Said Rimrodt, “Great care went into the testing of AlphaSan in regards to its effect on taste because of historical problems associated with organic antimicrobials.

“Unlike AlphaSan, organic antimicrobials inhibit the growth of microbes by slowly leaching into the surface of the plastic and subsequently into the bulk fluid,” said Rimrodt. By contrast, the AlphaSan technology was created to avoid this situation.

“Replicate taste tests based on industry-accepted standard methods were conducted to better understand the difference. The results of the testing proved the preference of AlphaSan-treated ice machine components to organic antimicrobial-treated parts.”

Rimrodt noted that AlphaSan works with such products as Guardian and Arctic Pure. “They act as the first line of defense to inhibit growth of microbes in an ice machine. Guardian serves to protect the interior environment against airborne microbes. Arctic Pure filters scale and lime from incoming water. AlphaSan inhibits the growth of microbes on the interior plastic components.” The package includes the AuCS cleaning system, which automatically releases cleaning or sanitation fluids into the machine “to remove any microbes that have penetrated and survived the first line of defense.”

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Sidebar: Technology Takes To The Road

Usually end users, dealers, and consultants have to travel to major trade shows or factories to view the latest in reach-ins, under-counter refrigerators, ice machines, and beverage dispensers. In recent months the Manitowoc Foodservice Group has been taking technology to its customers.

The traveling showcase of Manitowoc foodservice equipment is a 30-foot-long by 8-foot-wide custom-built showroom resting on a 32-foot trailer. The display places a major emphasis on Kolpak manufacturing capabilities and the R-Series walk-in.

The showroom has two interior compartments. One emphasizes features and benefits of a Kolpak walk-in unit. The other is a showroom of the latest innovations with McCall reach-ins and under-counter refrigeration, Manitowoc ice machines, and Servend beverage dispensers.

The road show made 90 stops in 13 states over a three-month period and was viewed by more than 500 guests. In advance of scheduled stops, potential customers are reached by invitations, followed up with a personal phone call. Guests received free gifts for visiting and were invited to register to win an Alaska vacation package.

One guest, Matthew Elliott from Atlanta Fixtures, commented, “We frequently don’t have time to get out to see every equipment manufacturer. This is great for the Manitowoc road show to come to us. It saves us an enormous amount of time and it is extremely educational.”

The company’s Web site ( has more information on all the products.

Publication date: 07/07/2003