Acta Univ. Agric. Silvic. Mendelianae Brun. 2008, 56(4), 169-176 | DOI: 10.11118/actaun200856040169
Vývoj pevnosti broskví během období sklizně
- Ústav techniky a automobilové dopravy, Mendelova zemědělská a lesnická univerzita v Brně, Zemědělská 1, 613 00 Brno, Česká republika
V práci je sledována závislost deformačních charakteristik broskví (Red Haven) na datu jejich sklizně. Deformační charakteristiky jsou stanoveny pomocí měření závislosti síla - hloubka penetrace válce o průměru 11 mm. Ukazuje se, že na této křivce je možné rozlišit různá stadia deformačního odporu daného ovoce. Proces deformace je popsán šesti veličinami (pevnost slupky, hloubka penetrace v okamžiku lomu slupky, tuhost, práce potřebná pro porušení slupky, pevnost dužniny a práce potřebná pro deformaci dužniny). Přestože dané veličiny vykazují tendenci k poklesu s termínem sklizně, pozorujeme značný rozptyl měřených hodnot. Tento rozptyl nelze eliminovat ani poměrně pečlivým výběrem sklízených broskví. Ukázalo se, že pro hodnocení pevnosti broskví je vhodnější spíše jednodušší metoda (např. klasický Taylor-Magnusův test), která stanoví jednu veličinu a která umožňuje snadné testování velkého množství vzorků, než exaktnější metoda umožňující získat velice podrobné informace pro několik málo vzorků ovoce. S ohledem na destruktivní charakter dané penetrační metody tak bude vhodné testovat jiné, nedestruktivní metody, např. metody akustické. Tento směr bude sledován v dalších pracích.
broskev, pevnost, penetrační test
Development of the peach firmness during harvest period
The objective of the present study is to characterize the rheological properties of peaches according to the results of puncture test force/displacement curves. The measurements were carried out on the universal testing machine. The firmness of the peaches was measured on the equatorial side of the fruit. Four measurements were carried out on each fruit by varying the orientation at intervals by about 90°. The used approach computed six texture parameters from the curves, which were supposed to be representative of skin hardness, fruit deformation before skin rupture, flesh firmness and mechanical work needed to penetrate the fruit. The data were fitted by an exponential function. The correlation is not statistically significant. Its value only support the hypothesis about decrease of the skin strength and other values. Generally, there is a decreases with time from the harvest beginning but the scatter of the data is too high. The results show that used method enables to describe the peach firmness development during the harvest period but the effective use of this method is based on the large number of experiments which are destructive in their nature. Some new approach is briefly outlined.
Keywords: peach, firmness, puncture test
Grants and funding:
The research has been supported by the Grant Agency of the Czech Academy of Sciences under Contract No. IAA201990701
Received: April 3, 2008; Published: November 8, 2014 Show citation
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