Mechanized harvesting and primary processing of Calendula officinalis L. Inflorescences

Abstract

Manual harvesting of marigold (Calendula officinalis L.) inflorescences results in superior quality, but requires enormous manpower. The objectives of the research were to examine the possibility of mechanized harvesting of marigold inflorescences by virtual rotating comb-type chamomile harvester, widely used in South Eastern Europe, and to develop the mechanical separator for the inflorescences from the harvested mass. The impact of coefficient R, ratio of the harvester's penetration into the inflorescences horizon and the width of inflorescences band (i.e. the average value of the highest and lowest inflorescences span) on the harvest yield, was tested first. Separation was performed by a bespoke separator that uses five cascades of oscillating sieves made of longitudinally situated rods. Influence of oscillation frequencies and rod distances on separation efficiency was investigated. It was found that, for coefficient R value of 1.3, an average of 97% of the total inflorescences yield can be harvested. The proportion of inflorescences with stem length up to 2 cm was 65% and 35% for stems over 2 cm. The result of mechanized harvest was the reduction in both the number of succeeding harvests and the yield, due to bud damages and elimination. The highest separation efficiency was obtained by using 2.7 Hz oscillation frequency and combination of 6/8 mm rods' distances in sieves. After three passes of the harvested mass through the device, approximately 92% of inflorescences were separated. Future investigations should be directed towards solving the issue of mechanical shortening of the inflorescences stems and evaluating the economic viability of mechanized harvesting within the proposed procedure.