Influence of reflective foil on the physico-chemical properties of apple fruits

Abstract

U intenzivnoj voćarskoj proizvodnji teži se primjeni novijih tehnologija u cilju poboljšanja kvalitete i fizikalno-kemijskih svojstava plodova. Pojedine sorte i njihovi klonovi imaju problem s razvojem boje plodova, a posebno u godinama s nepovoljnim vremenskim prilikama što se onda loše odražava na njihovu kvalitetu i tržišnu vrijednost. Danas postoje posebne folije koje se određeno vrijeme prije berbe postavljaju između redova u nasadu sa svrhom pospješivanja fotosinteze i poboljšanja refleksije svjetla u krošnju stabla. Cilj ovog rada bio je utvrditi utjecaj reflektirajuće folije 'Lumilys™' na fizikalno-kemijska svojstva plodova triju sorata jabuka: 'Wilton's ®Red Jonaprince', 'Jonagold Novajo®' i 'Fuji Kiku 8'. Za svaku se istraživanu sortu između redova postavila reflektirajuća folija 4 do 6 tjedana prije berbe. Plodovi su ubrani u optimalnom roku berbe, te su odvojeni isključivo zdravi plodovi (40 plodova sa svake sorte pokus i 40 plodova kontrole). Analizirana su slijedeća fizikalnokemijska svojstva plodova jabuka standardnim laboratorijskim metodama: boja, masa i dimnezije ploda, tvrdoća, indeks zrelosti, sadržaj ukupnih kiselina i topljive suhe tvari. Također, 20 plodova navedenih sorti čuvani su u periodu od 18 tjedana u hladionici (normalna atmosfera, 1 °C, 85 % r.v.z.). Analizom kromatskih vrijednosti prema CIE L*a*b sustavu boja utvrđeno je da su plodovi ubrani sa stabala gdje je unutar redova bila postavljena reflektirajuća folija imali veći intenzitet crvene boje, a manji intenzitet zelene boje. Pokus s folijom rezultirao je značajno većom masom, visinom i širinom plodova kod sorte 'Wilton's ®Red Jonaprince'. Plodovi u pokusu sorte 'Jonagold Novajo®' imali su najveći sadržaj ukupnih kiselina. Osim toga, značajno veći sadržaj topljive suhe tvari i indeksa zrelosti utvrđen je na plodovima pokusa sorte 'Fuji Kiku 8'. Također, plodovi sorte 'Fuji Kiku 8' iz pokusa nakon čuvanja imali su najveću tvrdoću i sadržaj topljive suhe tvari. Dobiveni rezultati istraživanja upućuju na veliki potencijal reflektirajuće folije u dostizanju, odnosno povećanju dopunske boje i interne kvalitete plodova. Upotreba ove mjere predstavlja vrlo kvalitetno rješenje tijekom prevladavanja nepovoljnih klimatskih trendova tijekom dozrijevanja jabuke.In intensive apple production, new technologies are being applied to improve the quality and physico- chemical characteristics of the fruit. Certain varieties and their clones have a problem with the development of fruit colors, especially in years with adverse weather conditions, which is than badly reflected in their quality and market value. Today there are special foils that lay before the harvest time between rows in the plant with the aim of improving photosynthesis and improving the reflection of light in the crown of the tree. The aim of this work was to determine influence of the reflective 'Lumilys™' foil on physicochemical characteristics of apple fruits 'Wilton's ®Red Jonaprince' ,'Jonagold Novajo®' and 'Fuji Kiku 8'. For each of the investigated species, reflecting foil was placed between the rows 4 to 6 weeks before harvest. The fruits were harvested in the optimal harvesting time, and only the healthy fruits are separated (40 fruits from each variety-experiment and 40 control fruits). The following physico-chemical characteristics of apple fruit that are analyzed by standard laboratory methods: color, mass and size of fruits, firmness, maturity index, total acids and the proportion of soluble dry content. Also, 20 fruits of the mentioned varieties were kept in the refrigerator for 18 weeks (normal atmosphere, 1 °C, 85 % r.a.h.). By analysis of chromatic values it was found that the products of trees where reflective foil was placed within rows, had a higher intensity of red color and lower intensity of green color by the CIE L*a*b color system. The experiment with the foil resulted in significantly greater mass, height and width of the fruits of the 'Wilton's ®Red Jonaprince'. The fruits in experiment of the cultivar 'Jonagold Novajo®' had the highest total acidic content. In addition, significantly higher soluble dry content and maturity index were determined on the products of experiment of the cultivar 'Fuji Kiku 8'. Also, the fruits of the 'Fuji Kiku 8' variety from experiment after the storage had the highest firmness and soluble dry content. Obtained research results suggest great potential of reflective foil in achieving or increasing the additional color and internal quality of the fruit. The use of this measure presents a very good solution for overcoming the unfavorable climatic trends during maturation of apple