* Food prices help drive record inflation * Nestle, P&G beat sales estimates * Nestle raises full-year guidance * Analysts warn consumers may grow tired of price hikes By Richa Naidu, Jessica DiNapoli and John Revill ZURICH/LONDON, Oct 19 (Reuters) - Nestle and Procter & Gamble, the world's two biggest consumer firms, reported better-than-expected sales on Wednesday, as shoppers continued to pay more for goods like Nescafe coffee and Gillette razors despite record inflation.