What is the best way to add fruit to a beer? I'm afraid boiling it will break down the fruit too much (a muslin bag could fix this I guess), but I'm not sure how to add it to the fermenter without contaminating the beer. I suppose this answer could depend on the fruit, too (bananas, blueberries, cranberries, oranges...)
You generally want to add fruit to the secondary fermentation. At this point, you already have alcohol that can help ward off any meanies hiding in your fruit. I am having trouble finding a source for this but I remember from a course I took that adding fruit to the primary will add more fruit smell and secondary would add more flavor. The smell part might be wrong but adding during the secondary definitely imparts more flavor.
As far as sanitation before hand, you have a few options. Give the fruit a rinse and any prep it needs (cubing, peeling, etc) and decide whether you would like to heating it, freeze it, or just add it. They all have their own downsides. Obviously just adding it has the biggest risk of infection, but I have done it successfully with great results. Freezing is an option (and I usually do this to allow me to save some fruit for later if I want to do multiple additions) but I don't think it actually kills all of the meanies, just puts them into hibernation. Heating for 10 minutes or so should be good. The downside to boiling is that you will have pectins, which will create a hazy beer. Which is fine if you are making a wheat anyway.
It depends on what you're doing really. Adding fruit can be risky as there is always a chance of contamination.
I've made fruit beers before and didn't want to boil them and lose a bunch of flavor. So instead I opted to freeze the fruit, and then slowly thaw it out in the fridge. Now keep in mind that freezing will not guarantee no contamination, but it will reduce the risk. At this point I added it during secondary fermentation. This helps reduce the risk of contamination because all of the fermentable sugars have been eaten, and there's less in there for bad bugs to eat.
If you're really skiddish about adding raw fruit to your beer, but don't want to sacrifice much in the way of flavor, add your fruit during the last 5 minutes of the boil.
If you're looking to add real fruit to any brew you'll want to do so in secondary to get the most flavor. I've had really good success in taking my fruit of choice and pureeing it in a food processor with little vodka - about 1/4 cup per 2lb of fruit seems a good balance.
The vodka will help kill off any additional bugs that may have made it past washing the fruit, but won't add hardly any alcohol or off flavors to the beer itself. That process worked amazingly will for a mixed berry saison I brewed this past spring.
We did some fruit pale ales last year with dehydrated fruit. We have a dehydrator and dried the fruit at 165 to kill off baddies and sealed it up till use. We did pineapple, kiwis, strawberries and chili peppers, non had any infection, even 6 months after. So it's an idea.
Also the strawberry tasted amazing!
I have always just added the fruit to secondary. I cleaned the fruit, but did not boil it or otherwise try to sanitize it.
The alcohol content in the beer (which will be present when adding the fruit in secondary) should make it difficult for the little buggers to grow.
I have had some issues with infection, especially when doing this with strawberries. These issues have come about after a couple of months, though, so if you drink it quickly, it should be fine. Essentially, you get a shorter shelf-life, but if you enjoy your creation soon after making it, you should be fine.
If you are really worried about it, you could use fruit extract. I've done that and wasn't crazy about the flavor. I made a cherry wit a few weeks ago and I froze my cherries and thawed them in the fridge. I then added them to a muslin bag at the same time I moved to secondary.
I like the method described by Dogfish Heads Sam Calagione in the book Extreme Brewing
Method is to do a fruit addition and rest during the wort chill
Chill to 170° and hold for 20 minutes. The book has a nice road map for most popular fruits and their slight temp and time differences. This method is nice as it sanitizes the fruit but doesn't cook it and let's the fruit contribute to the fermentables and giving more fruit profile than a secondary frozen addition.
I've tried the method once but unfortunately I had a defective fermentor and never got a taste.
I've never had a problem with infection when adding raspberries to the secondary with my chocolate raspberry stout, but by then, the alcohol was at nearly 8%. I usually add about 3# fresh or previously frozen for a crisp, subtle flavor that paired beautifully with the chocolate. It aged in the bottle very well, as the berry flavor stayed intact. I wonder, though, if adding frozen berries to the wort at flameout would bring good results as well, in addition to aiding the speed of the cooling process?
My friend who made a kick ass imperial cider told me that he baked about 5 pounds of apple slices in the oven, then immediately put them in the freezer for 24 hours. Then plopped them in the secondary for 2-3 more weeks. It turned out awesome! So now I'm going that route. Although I'm not making a cider, I needed to add about 1.5 pounds of apples to my Chai Beer. So I'm doing it this way. It's called "Make Them Chai Slowly"....yeah, a little wordy.
I would try different times/techniques with different fruits. One of my favorite things to do is when I'm trying different things, to split the batch into two 2.5 gal batches so I can compare and contrast. I would definitely say secondary is best. But on how much, whether to freeze/sanitize, etc. take a look at my fruit experiments here. Just don't be afraid to try it! http://brewingoutofbounds.blogspot.c...r-already.html
I did a small batch of Pale Ale + Fruit in January. I made a smooth puree and pasteurized it by heating on the stove to 80C and holding that temp for 30 minutes. I put the puree in the secondary and racked the beer onto it.
I had a fairly vigorous secondary fermentation as the us-05 chewed through all my fruit sugars. This took away almost all of the fruit flavor I was trying to impart, but made an interesting beer.
Next time I will use flavor extract. I really wanted to use real fruit, but I feel that this is probably the only way to get the flavor I want. Silver Cloud Estates seems to be a popular source for beer flavor extracts.
I make an apricot and raspberry ale and add the fruit right after the boil. I would never have done this but a master brewer at Norther Brewer said that's the way he always does it. His apricot ale has won many 1st-3rd place awards. I changed it up a bit but it now seems perfect. 5lbs at flame out/boil end for a lot of flavor and aroma. 3lbs at flame out if you want less flavor and aroma. The temperature is hot enough to kill all the nasties. It's over 160F and it really works great. The heat really pulls out the flavor and aroma fast plus it kills bacteria.... I have never had any negative issues. The only thing that you have to do is filter out the fruit when pouring your wort into your carboy! Don't make the mistake I made the first time I did this with raspberries. I didn't puree them and the seeds were sitting at the bottom of my bottles! It was still delicious but what a pain. They mostly sat in the sediment but pouring slow helped. Freezing will do nothing for the bad stuff but boost the flavor. Boiling will cause loss of flavor, aroma and cloudiness. Drop your puree in at the end and you will have very clear, "nasty" free brew. Also, with strawberries, no cloudiness! Basically, your fruit will be added so early you won't have the mess in your second carboy and very clear brew. Just a different idea! Good luck and happy brewing.