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• Effect of certain bentonite products on the temporal variation of elemental content in white wine

  15-21.

  N. Rakonczás

  Z. Kállai

  G. Antal

  B. Kovács

  I. J. Holb

  Views:

  143

  The 'terroir' character of wines can be shaped with certain technological elements such as bentonite fining. Bentonite is an agent used for the removal of thermolabile proteins in wines. However, during fining, the quantity of certain wine components can change, including the elemental composition of the wine. According to the recommendations of bentonite suppliers, wines should be racked off the bentonite fining sediment within 2-3 weeks. However, in winemaking practice, wines can remain on bentonite fining sediment for up to 1-4 months. One reason for this is that racking wines off the sediment has a negative impact on wine quality. Thus, it is a question of how much the later or earlier racking time can alter the elemental content of the wine. Our study aimed to examine the elemental content of wines treated with three different bentonite products sampled from over the bentonite fining sediment at various time points. Our investigation was conducted with the 2019 vintage white wine of the University of Debrecen. Fining was performed with three bentonite products: Nucleobent, BW200, and Granubent Poretec. The sampling schedule following fining was: 0 days - unfined control, 7th, 14th, 27th, 56th, and 85th days. The macro-, meso-, and microelement contents (P, K, Ca, Mg, S, Al, Na, B, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd, Ba, and Pb) of the wines were determined using ICP OES and ICP MS devices. Our results showed significant changes in the Al, Na, Cr, Fe, Co, Ni, Sr, Ba, Cu, and Pb contents of the wines depending on the sampling time. It is noteworthy that all three bentonite products increased the Al and Pb contents of the wines. For Fe, dynamic increases were observed over time with the BW200 product, reaching the threshold value of susceptibility to brakeage. However, from a winemaking technology perspective, it was favorable for the Cu content of the wines to decrease with both earlier and later racking times, for all bentonite products examined. Based on the elemental analyzes of the white wines studied, it can be concluded that racking of wines should be timed according to the recommendations of suppliers.

• Yield and fruit quality response to foliar application of biostimulants in an apple orchard

  17-23.

  Adam Csihon

  Marianna Sipos

  Imre Holb

  Views:

  531

  Nutrient supply plays an important role in fruit production technology. Among the methods of nutrient management, the application of foliar fertilization has become an essential tool to harmonize the vegetative and generative performance of fruit trees. This study was conducted to determine the effect of four foliar fertilizers (Bistep, brown juice, Trichoderma harzianum, Clonostachys rosea) on yield and fruit quality in an apple orchard with the cultivar ‘Pinova’, at the University of Debrecen in Hungary. Trees were trained to a slender spindle canopy with a spacing of 4 × 1 m. Treatments were applied five times during different phenological phases in 2021 and 2022. Based on our results, biostimulants had a positive effect on fruit yield and fruit quality, but extreme weather events also influenced the data. In 2021, the effect of the treatments on yield data could not be observed (10.1–13.5 kg/tree; 0.16–0.24 kg/cm²). However, in 2022, plants sprayed with Bistep, T. harzianum, and C. rosea reached 28.7–31.2 kg/tree (0.33–0.46 kg/cm²), while control trees produced only 19.8 kg/tree (0.20 kg/cm²). Fruit size development improved with an increase of 2–6 mm over the two years. Among the treatments, Bistep was able to enhance fruit surface coloration to a greater extent in 2021, as red skin color reached 44% for this foliar fertilizer, while control trees presented only 27%.