You currently have your gallery embedded within two iframes (an iframe within another iframe).
The first <iframe> on your 'Food' page is as follows:
<iframe class="page_food_fAmI1LvscHaNb76gfLVOv" frameborder="0" src="/cgi-bin/snippet.cgi?todo=as_page;instance=4577826729;num=1;community_id=4011990497" scrolling="no" allowTransparency="true"></iframe>
The page loaded into this iframe loads your gallery into another iframe.
Also, the page containing the second iframe does not use a Doctype Declaration. (All web pages should use a Doctype Declaration to inform the user's browser what set of standards the code on the web page should conform to.)
Try taking an iframe out of the equation and replace the above code with the following:
<iframe src="https://dl.dropboxusercontent.com/u/37903739/juicebox_gallery_food/food-index.html" width="1050" height="600" frameborder="0" scrolling="no"></iframe>
I do not know how you are adding the iframe to your Moonfruit page but there should be no need to have a second iframe (especially on a page with no Doctype Declaration) so perhaps Moonfruit support could help you out with this.
The double iframe and lack of Doctype Declaration on the page containing the second iframe may be contributing to your problems.
Also, try temporarily setting captionPosition to something other than NONE in your gallery to see if this helps.
There is a known bug (which has been logged and should hopefully be fixed in a future version of Juicebox) whereby a gallery with captionPosition="NONE" loaded into an iframe flickers in WebKit browsers (Chrome, Safari, Opera). This bug may also manifest itself in Chrome and Mobile Safari on mobile devices.