hasil 'fermentasi spontan' (fermentasi yg terjadi secara alami (oleh yeast 'indigenous') tanpa penambahan yeast lagi memang enak . *jurnal mode on* Beberapa penelitian mendukung hipotesis bahwa active dried yeast (yeast yg diawetkan/dikeringkan) mengurangi variabilitas strain yang muncul dalam fermentasi spontan (Frezier and Dubourdieu, 1991; Beltran et al., 2002 dalam Jeune et al., 2006) dan, mungkin, kompleksitas wine yang dihasilkan. Untuk alasan tersebut, pembuat wine yg mencari flavor original lebih suka fermentasi spontan dengan yeast alami/indigenous (Jeune et al., 2006). btw metabolisme yeast: substrat (gula sederhana) + yeast, dalam kondisi anaerob maupun semi aerob akan menghasilkan alkohol dan CO2. hmm, 2 hari 1 malam dah ada lho alkoholnya..
(sumber tabel: Polychroniadou et al., 2003)
(metode): A strain of Saccharomyces cerevisiae yeast was used in all fermentations. Fermentations were all carried out in duplicate and in 1 l spherical flasks with flat bottoms. The fermenting volume was 250 ml and 5 g/l pressed yeast cells were used as starter cultures with no pH adjustment. The fermentation temperature was 30 °C. Samples were collected at the end of the fermentation and analyzed for volatile by-products (acetaldehyde, ethyl acetate, propanol-1, isobutyl alcohol, amyl alcohols and methanol). The produced grape wine, apple juice wine (cider) and whole apple pulp wine (unfiltered) were left in the bioreactor with yeast in for a month at 30 °C while monitoring signs of visual spoilage including turbidity, formation of surface films, color changes and viscosity.
kalau penyimpanan wine sampai bertahun2 itu untuk aging, menyempurnakan flavor, tapi alkohol sendiri sudah terbentuk sejak awal. (contoh lain: pada pembuatan roti, beberapa jam saja (tidak sampai setengah hari) sudah jadi roti (matang/sudah dipanggang) dengan rasa & aroma yg sedap salah satunya akibat alkohol..
)daftar pustaka: jurnal (ScienceDirect)
- Evolution of the population of Saccharomyces cerevisiae from grape to wine in a spontaneous fermentation
- Grape and apple wines volatile fermentation products and possible relation to spoilage
