Article Appearing in the November 1997 Issue of Great Lakes Fruit Grower News

Cider pastuerization facts need to be put into perspective

By Bob Curry of Goodnature Products

With pasteurization such a politically charged word it might be useful to put a few facts into perspective.

It appears inevitable that pasteurized cider, for better or worse, has become almost overnight an accepted, and sometimes even preferred product for the American consumer. The debate over the necessity or desirability of pasteurization is moot if the market demands it. While I will continue buying fresh cider for my family from cider makers I trust, most consumers probably have neither a personal connection to the cider maker, nor confidence in their own grasp of food safety issues.

Basically, pasteurization is what home canners have been doing to home grown produce every fall for decades. Those who can apple cider, are well aware that fresh cider is different from canned juice that they open in the winter. When canning, the cider is subjected to high heat (up to 212F) for a long period (15- 30 minutes) of time. Even if the actual heating of the juice lasts only a few minutes, it takes many minutes for the juice to cool.

Very noticeably - when you exceed 175°F (give or take depending on the variety and condition of the apple) the pectin in the cider denatures and drops out of suspension. This results in a juice that is almost clarified on top but has a thick "cloud" of formerly suspended solids on the bottom. Several national brands of "natural style" apple juice (After The Fall and Knudsen's) have this appearance from time to time. Obviously this condition changes the look, "mouth feel", and taste of the juice and - to many cider makers - is absolutely undesirable for their product.

Enter flash pasteurization

Though some large industrial juice makers have lately made flash pasteurization sound like something fresh from the laboratory and designed specially for juices, it is a process that has, in truth, been around since at the 1920s with the development of the first H.T.S.T. (High temperature short residence time), regenerative plate pasteurizer in England.

Flash pasteurization differs from conventional canning style processing in several ways.

The time it takes to rise from ambient to pasteurization temperature takes several minutes when canning but only a few seconds in flash pasteurization. A flash pasteurized liquid is held for only as long as is required to kill a percentage of certain organisms at a specific temperature. When canning the idea is to kill all or nearly all spoilage organisms.

In the case of cider, Cornell University has determined that at 155° F , 99.999% (a "5 log reduction") of the E. Coli O157:H7 is killed after six seconds. Since the cider in question is not going to be treated by the consumer as a shelf-stable product the other spoilage microorganisms don't have to be killed. The astute cider maker will probably think the numbers above are in error. In fact the temperature for a five log reduction is 155°F for six seconds. Cornell's formal recommendation included a safety factor of five degrees (160°F for six seconds).

Flash pasteurization implies rapid cooling from treatment temperature back to some much cooler, condition. Canning, on the contrary, involves air cooling a mass (whatever is contained in the jar) to room temperature over an extended period of time.

The bottom line is that flash pasteurization is designed to heat liquids, kill the undesirable organism, and cool the liquid, before the captive liquid knows what has happened to it. To the degree you minimize your heat and holding times you will also minimize degrading your product.

See for yourself

Goodnature is hoping to demonstrate this concept at the Michigan hort show by pasteurizing samples of cider brought to the show by local cider makers. Samples of cider will be available both before and after pasteurization so that folks can see that, if done properly, it is nearly impossible to taste the difference between pasteurized and non pasteurized cider.

Color

The one difference that is noticeable between raw and pasteurized cider is the color. The polyphenol oxidase enzyme that changes the hue of apple cider into a dark brown color is inactivated by heat. So if you pasteurize right off the press it will "freeze" the cider at whatever color it is at the time. Thus, if your cider turns dark over the course of a day, and you begin pasteurizing immediately after pressing, your cider will now retain its light fresh pressed color.

The bad news

Pectin - the sublime substance that, more than anything, differentiates cider from juice, is also what makes pasteurizing cider rather difficult. As any home canner knows, pectin is what separates juice from jelly. In the presence of heat, sugar, acid and water (all items present in the making of jelly and pasteurized apple cider) pectin is well known for creating jelly. In the thin gap separating a pasteurizer's heat exchanger plates, this buildup of jelly is deadly. It is astonishing how quickly a high tech device like a pasteurizer is brought to its knees by such an innocuous seeming substance as pectin.

Curiously, the professor who invented enzymatic depectinization, for which the first patent was issued back in 1930 (Dr. Peterson of the New York Agricultural Experimental Station in Geneva New York) wondered who would even use his discovery - because he couldn't imagine clarified juice becoming very popular. How things change in a few short years.

The creation of clarification, in fact, was less for the benefit of the consumer than for the processor. The few processors who still pasteurize raw cider (before this year, that is, during which probably 75 cider mills have begun pasteurizing) all have to clean their units more frequently and vigorously than when pasteurizing clear juice so that the pectin does not build up and affect their process and product. Not only will pectin gum up a pasteurizer, but it wreaks havoc on any attempt at filtration.

In fact, apple juice manufacturing today implies that all the lovely pectin that we value for the mouth feel and health benefits it contributes to cider (ever wonder what one of the two main ingredients in Kaopectate is?) is chemically broken down with synthetic enzymes and then removed so that this pesky pectin won't get in the way of the processors.

Since most of the pasteurizers that Goodnature built before this year were for juice or juice concentrate plants, the added requirement to counteract the effects of cider pectin were not completely known even to us. As we developed a line of small pasteurizers we discovered that the manufacturers of plate heat exchangers (the plate packs that allow heat to be transferred from a heating medium to the cider) were not even aware of the true viscosity of cider or effects of pectin. They were accustomed to dealing with beer, milk, or depectinized juice.

From the experience we gained while working with cider producers in more than 10 mills this summer and fall, we came to the conclusion that the standard pasteurizer plate is not an ideal design for pasteurizing cider. Though the standard plate does the job it is intended to, it is highly susceptible to becoming coated and even plugged with pectin.

New pasteurizer

Never content to be satisfied with the status quo, Dale Wettlaufer, president of Goodnature, got together with his chief engineer, Richard Hess, and began redesigning the heat exchanger plates from the ground up. The idea was to simplify their design to reduce cost (the plate sets represent the lion's share of a pasteurizer's cost); and changed the design to make it more difficult for pectin to build up.

The result is the Goodnature MFP or Micro Flash Pasteurizer. The cost for the units is significantly lower than of what a standard pasteurizer costs without sacrificing any of the standard safety features. Also, the incidence of fouling from build up of pectin is significantly reduced.