I wouldn't call having a chat during a coffee break, *a perk*, even if it were work related, although you would be easily understood and you obviously intend it in a droll or tongue-in-cheek manner. As this will be only in the acknowledgement section of your thesis, you could very well leave "perk" in.

However, perk, as a noun, is not usually used in that sense. 

[WordNet](http://wordnetweb.princeton.edu/perl/webwn?s=perk&sub=Search+WordNet&o2=&o0=1&o8=1&o1=1&o7=&o5=&o9=&o6=&o3=&o4=&h=) has this to say:
*(an incidental benefit awarded for certain types of employment (especially if it is regarded as a right) "a limousine is one of the fringe benefits of the job"* It is short for [perquisite](http://www.thefreedictionary.com/perquisite); *a payment or profit received in addition to a regular wage or salary, especially a benefit expected as one's due*



Normally we talk about the perks of a job, working for a company, holding a particular title or position. 

 > Having travelling costs covered by your company is a huge perk.     
One of the perks of this job is that I get free health insurance.   
> He refused to hand back £30,000 worth of perks from his £201,000
> retirement package

Alternatively, simply state that the coffee breaks shared with Jason Wright were both entertaining and rewarding, or words similar to that effect.