Is there a standard deduction for food purchases or do you have to save receipts. I am an independent contractor over the road truck driver

If you are self employed, there are no standard deductions. Go to IRS.gov and print out a 1040, SE, and Schedule C, and depreciation of your truck form. Sch C is where you itemize deductions, including food. SE is Social Security tax. 1040 is all the usual. If you need help with depreciation, take it all to a tax preparer this time.
You should save receipts for every little thing - tolls, gas, food, anything. If you don't, estimate and hope you don't get audited.
Tax Deductions for Truck Drivers (http://taxes.lovetoknow.com/tax-deductions-credits/tax-deductions-truck-drivers)

As a trucker, you are authorized a daily per diem deduction of about $60 per day which requires no receipts. You need only prove that you were on the road on a contract.