Various mistakes made during brew.

So I brewed a Belgian white beer.
It asked for a 30 minute boil.
Adding 1/2 ounce cascade hops
then for the last 15 minutes- orange peels and coriander
Then for the last 5 1/2 oz cascade for aroma.

So I screwed up at put all the cascade in when the first 1/2 oz was suppose to go instead.

How badly is this going to mess with the taste?

Also my oG was off it was lower than it was suppose to be? How bad is this and what caused it.

Well it is hard to say exactly what the impact would be without a bit more information (boil volume and content especially). However, you wouldn't normally expect that style to have significant aroma hops, so it shouldn't be a problem from that perspective. You will end up more bitter than you were shooting for though, which may carry it a bit out of style. Cascade is on the mild side (though not conventional for that style), so I wouldn't worry too much about it.

Were you using extract for this recipe? If so, your OG is probably closer to the estimate, but you may not have gotten it mixed up well enough. That happens a lot with extract brewing.

two 1/2 gallons of water was used to seep the grains and so on. it was lme extract

I am not at home, so I can't do the calculation, but I can't imagine you could squeeze too many IBUs out of an extra half ounce of hops in a thick wort of only 2.5 gallons. I think you would be fine. If you post the lbs of LME, I will try and run the numbers in beersmith tonight and let you know where your approximate IBUs should be. I am guessing the Cascades were about 5-6 AA%?

Exact AA% is not known. It is listed as medium on Austin home brew site where i got the kit. 6 pounds of lme.
I guess i will just see out it works out and just brew another one tomorrow in case it doesn't taste good.
Thanks for all your help

The point of boiling hops for an hour plus is to isomerize alpha acids, which add a bulk of the bittering taste. The actual hop flavor and aroma are mostly lost in the boil. Adding the hops later is to minimize the process of boiling away those hoppy flavors and aromas, and limit the bitterness. Worst-case scenario, your final product will be slightly more bitter, with a little less hop prescense. Like Duck, I'm not prepared to do the calculations, but I'd bet the overall effect will be minimal. (Don't quote me on that, I'm a noob)

^^^^^

What he said.

Also, with respect to the gravity: It's a lot more difficult than most new brewers think to fully mix the high-gravity wort and top-off water. That leads to artifically low OG readings.

RDWHAHB. You're good, and in the end, you'll have beer.

I messed around a bit with the recipe in Recipator. I actually think that the recipe should have called for 1 oz. of hops at 30 minutes to get the proper amount of bitterness. Here are the assumptions I made on Recipator:

Boil volume: 2.5 gallons
Final volume: 5 gallons
OG: 1.049
Cascade alpha acid: 6%
IBU calculation method: Tinseth

Using 1 oz. of hops at 30 minutes gives 10 IBUs. Using 0.5 oz. at 30 minutes and 0.5 oz. at 5 minutes gives 5 IBUs.

The BJCP style guidelines for the style says the IBUs should be between 10 and 20. I think if you would have followed the recipe, your IBUs would have been way to low. You should have a delicious beer!

If you want to try what I did, here is the link to Recipator. I use it to develop my recipes, and I'm pretty happy with it.
The Beer Recipator - Home

Cool thanks everyone! Thanks to for that link especially!

Here is a collection of stories that I put together during the influx of post Christmas "nervous noobs" that we get a huge influx of every year.

https://www.homebrewtalk.com/f39/wh...where-your-beer-still-turned-out-great-96780/

Our beer is pretty resiliant.