Grapefruit which are produced in the desert areas are not mature unless they meet the following requirements:

The differences in climatic conditions that prevail in the desert areas result in the grapefruit grown in those areas having, at maturity, a higher percentage of soluble solids to acid than the mature grapefruit which are grown in other areas of the state. Grapefruit which are produced in the desert areas are considered mature if at the time of picking, and at all times thereafter, the juice contains soluble solids equal to or in excess of six parts to every part of acid which is contained in the juice. The acidity of the juice shall be calculated as citric acid and without water of crystallization.