Till you get out of orissa, you will get hawkers selling various food varieties inside the coach, itself - even if it is 2A. but once when the train enters andhra - you have to get down to stations.
In andhra if you are interested to buy dry grapes from hawkers inside the coach, dont feel any urgency. The offer starts at 3 packs for 100INR and goes till 10 packs for 100 INR.