The HPLC techniques on C₁₈ with the UV detection were used to study the effect of technology, season of processing and storing on the organic acid contents in and composition of concentrated apple juices. The season of processing influenced the composition and the total content of organic acids. Different technology steps had a low effect on organic acids except for a step of pomace enzymation (liquefaction). Storing the concentrated juices during 1 and 2 year periods at 4°C resulted in the quantity decrease of malic acid (ca 2–14%) and total acids (ca 2,5–10%), whereas the value of pH and the extract increased.