GS1-128 barcodes are the industry standard in many segments of the food industry especially when the item is sold by weight. Examples include the meat industry, cheese industry and the produce industry. These barcodes consist of multiple segments and by scanning the barcode you can pick up those multiple pieces of information in a single scan. Here is a short video on understanding these barcodes.
Watch the video and then for a full list of the segments that could be in your GS1-128 barcodes, this Wikipedia list is a great resource. The important segments for using these barcodes for traceability are the (10) which is a lot number segment or the (21) which is a serial number segment. Serial numbers are used when each case has a unique weight associated with it and the customer is typically buying that product at a $/kg or $/lb.