I wouldn't call a chat during a coffee break, *a perk*, even if it was work related. Saying that, it's clear your meaning and it may be interpreted as being droll or tongue-in-cheek, hardly a negative thing. Since this comment will only be in the acknowledgement section of your thesis, you could very well leave "perk" in.

However, the noun perk, 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.