CHANGES IN QUALITY ATTRIBUTES DURING GROWTH OF LEEK (ALLIUM-PORRUM L)FOR INDUSTRIAL PROCESSING

A field experiment with leek was conducted in 1990 and 1991. Plant wei ght and the contents of nitrate and dry matter of the leek were measur ed on ten successive harvest dates each year. The yield of dry matter per square metre was calculated and related to harvest time. A maximum and virtually constant average plant weight was obtained from the beg inning to the end of October (weeks 41-44). After this time the plant weight decreased. The yield of dry matter per square metre was virtual ly constant during the last two weeks of October and the first week of November. The content of nitrate decreased steadily during the harves t period, while the content of dry matter was at a minimum in the midd le of October (week 43). The changes in nitrate and dry matter during growth could be explained by results from analyses of the different co mposition of the fractions of the leek. The content of nitrate and dry matter decreased from the outer to the inner part of the leek, in whi ch the major part of the growth takes place during the weeks up to har vest. A maximum yield of fresh weight and dry matter can be obtained a fter harvest in October or November (weeks 43-45) when the content of nitrate has decreased to a low and almost stable level.