The document provides guidelines for quality assessment, and quality index attribution, of original data from scientific literature and laboratory reports. This system was inspired by existing systems (USDA, AFSSA, BASIS, CSPO, and BLS) and allows compilers to evaluate the quality of original data according to common guidelines based on eight scores: Food description Component identification Sampling plan Number of analytical samples Sample handling Sample analysis Analytical quality control Sum of 1-7 Together the eight scores form the quality index (QI).To help compilers with evaluation, a set of criteria is proposed within each category. Answers to these criteria guide the compiler through evaluation and each category receives a score from 1 to 5 (low to high). All scores are then summed to form the QI.Examples are provided at the end of the document. Key wordsCategories: set of items to be assessedCriteria: standard used to assess qualityScore: total number of points assigned to each categoryQuality Index: sum of the score of each category giving an overview of the quality (quality index - QI)Confidence code-CC: alternative way to express QI that is in general expressed as A, B, C or D