Ask Mr. Wizard

Sanitizing bottles in a dishwasher


Chris Vaughn • West Chester, Ohio asks,

I have heard many people talk about sanitizing bottles and have heard different opinions. The two most common opinions are: 1. Never use a dishwasher, always clean with sanitizing solution in a sink. 2. You can use a dishwasher but use high temperature wash/heat dry cycle and no cleaning/sanitizing solution. I know that the sanitizing in a sink works, but I have never tried the dishwasher technique. What do you recommend?


I have heard the same pearls of bottle-washing wisdom you cite in
your question. I have also heard similar suggestions made about all
sorts of other bottle sanitizing practices and often find myself
wrinkling my forehead thinking, “Well, what do the big boys do?” When it
comes to washing and/or rinsing bottles it is indeed helpful to look at
what commercial brewers do because they are pretty knowledgeable about
washing bottles.

At one time it was common for brewers to wash and reuse bottles. Times
have changed, though, and it is nearly unheard of for brewers in certain
areas of the world to use returnable bottles. In the US, for example,
the use of returnable glass is all but gone. However, returnable glass
is still common in some countries and brewers continue to clean all
sorts of things off of bottles (inside and out) before filling. Bottle
washers are the industrial equivalent of giant, continuous dishwashers.
Several stages of cleaning are present in bottle washers, including hot
caustic soak sections, caustic jet sections, hot and cold water rinse
sections and a final rinse with fresh water. This kind of machine gets
the bottle clean. Following cleaning, returnable glass must be inspected
for any defects, such as chips and cracks, and most of this inspection
is now performed with in-line imaging equipment.

New glass does not have to be washed before filling, and that is
certainly one of the appeals of using new glass for a brewer. Whether
using new bottles or returned and cleaned bottles, a bottle-rinsing
machine is almost always used before bottle filling. Twist rinsers were
once common but have largely been replaced with rotary rinsers that have
a much smaller footprint. Some brewers use a liquid sanitizer in the
rinser to kill contaminants before filling. The most effective
sanitizers in this operation are those with a fast kill time and these
are usually oxidizers, such as chlorine, ozone and peroxide. The problem
with these sanitizers is that they can oxidize beer, especially
ozonated water and peroxide solutions, and, in the case of chlorine,
lead to significant off-flavors. The preferred sanitizer these days is
steam. Steam has a quick kill time when used as a sanitizer, is
relatively inexpensive, is easy to control and, provided that the steam
is free of contaminants, leaves no residuals in the bottle that affect
beer stability or flavor.

So what does any of this have to do with your question about cleaning
bottles at home? For starters, it illustrates that commercial brewers
use cleaning machinery. So the one camp that says, “never use a
dishwasher” is pretty much out of touch with reality because commercial
brewers are running specialized “dishwashers” across the globe. The
other camp suggesting that it is OK to use a dishwasher as long as a
cleaning solution is not used is also a bit out of touch, however. I
think both suggestions have merits, but clarification is required.

One of the practical problems with dishwashers is that a dishwasher is
not always the cleanest thing in the kitchen. Television commercials
showing a dishwasher full of dishes covered in food totally disgust me. I
am one of those dishwasher users who loads the dishwasher with very
well-rinsed utensils, plates, glasses, etc. If your household has a
clean dishwasher, using it to clean bottles is not, in my opinion, a
terrible idea. You can always clean the inside of the dishwasher by
running it empty and inspecting it after cleaning for
any residuals.

When it comes to detergent selection for bottle washing, you want to
choose a detergent that is designed to attack the target soil and leaves
nothing behind. If you choose an unscented, all-purpose dishwashing
detergent you should be fine. I like some of the newer detergents on the
market that have sodium bicarbonate (baking soda) as the primary
ingredient. Baking soda really is a great cleaner for glassware provided
that there is not too much heavy soil, which is something that a
homebrewer directly controls.

If you rinse your bottles after emptying for consumption there will be
little soil to remove and there is no reason to use an excessive amount
of detergent or the most aggressive cocktails designed for a bunch of
greasy plates. You probably will find that using half the recommended
amount will work just fine for cleaning rinsed bottles. Running a second
rinse after the cycle is complete may give you a higher level of
assurance that there is nothing on the surface of the bottle. The hot
dry cycle will leave your bottles in a clean and dry condition for use.
However, if you are packaging carbonated beer you will definitely want
to fill your beer into a bottle that has been recently rinsed with water
so that the surface is wet; this helps prevent foaming caused by rough,
dry surfaces.

Dishwashers do have a pretty bad reputation for destroying clear
glasses. I have washed my beer and wine glasses by hand since first
discovering the odd odor and appearance of glasses washed in
dishwashers. It turns out that glass is etched by soft water when the
water temperature is over about 140 °F (60 °C). Since most dishwashers
heat water to about 160 °F (71 °C), which accelerates the reaction, this
type of glass damage is common in areas with soft water or in
applications where water is softened. Hard water may leave a film
behind, but hard water spots and films can be removed with a mild acid
like vinegar.

If this all sounds like a big hassle, you can simply soak your bottles
in a mild detergent, rinse and dry. Whatever you decide to do, though,
just make sure you are using clean glass on bottling day.

Response by Ashton Lewis.