Transformacija problematičnog vinskog otpada u vrijedan supstrat za proizvodnju pekarskog kvasca i čvrstog biogoriva: princip kružnog gospodarstva

Research background. Wine production, which is considered a major sector in food industry, often involves the use of a large amount of resources. Moreover, wine making generates a large amount of grape pomace, which is generally used for low-value applications such as fertiliser and animal feed. The aim of the present research is to explore the possibility of improving the overall sustainability of traditional winemaking. Experimental approach. A zero-waste process was developed. It includes the production of white wine and the substantial valorisation of grape pomace, which is converted into solid biofuel, tartaric acid and concentrated grape extract as feedstock for industrial baker’s yeast production. Results and conclusions. We estimate that a significant surplus of renewable energy of approx. 3 MJ/kg processed grapes can be obtained during this conversion. The suitability of grape extract as a potential substrate for industrial baker’s yeast production was evaluated and the feasibility of a partial replacement of molasses (up to 30 %) was demonstrated. Novelty and scientific contribution. We present a circular economy approach for the conversion of winery biowaste into high-value resources such as feedstock and solid biofuel.Pozadina istraživanja. Proizvodnja vina, koja se smatra važnim sektorom u prehrambenoj industriji, često uključuje korištenje velikih resursa. Osim toga, nakon proizvodnje vina zaostaju velike količine komine grožđa, koja se obično koristi za dobivanje proizvoda niske vrijednosti, poput gnojiva ili stočne hrane. Svrha je ovog znanstvenog rada bila istražiti mogućnost poboljšanja ukupne održivosti tradicionalnog postupka proizvodnje vina. Eksperimentalni pristup. U radu je razvijen postupak koji uključuje proizvodnju bijelog vina i značajnu valorizaciju komine grožđa, koja se pretvara u čvrsto biogorivo, vinsku kiselinu i koncentrirani ekstrakt grožđa kao sirovinu za industrijsku proizvodnju pekarskog kvasca. Rezultati i zaključci. Procjenjujemo da se ovom metodom može dobiti značajan višak obnovljive energije od otprilike 3 MJ/kg obrađenog grožđa tijekom postupka. Istražena je moguća uporaba ekstrakta grožđa kao potencijalne sirovine u industrijskoj proizvodnji pekarskog kvasca, te je dokazana mogućnost djelomične zamjene melase s ekstraktom grožđa (do 30 %). Novina i znanstveni doprinos. U radu predstavljamo princip kružnog gospodarstva pri pretvaranju biološkog vinskog otpada u visokovrijedne resurse, poput sirovina i čvrstog biogoriva

Reshaping Apple Juice Production Into a Zero Discharge Biorefinery Process

In the last decade, the utilization of waste by-product apple pomace has been extensively researched (due to its difficult disposal) and currently finds beneficial usage in various industries; as substrate for microbial growth or recovery of pectin, xyloglucan and polyphenols. In this research apple juice was produced at pilot scale. Furthermore, apple pomace was employed as substrate for the production of pectin, biofuel (pellets) and concentrated apple pomace extract. Extensive mass and heat balances were conducted to evaluate the feasibility of this approach on industrial scale. The produced pellets had very similar characteristics to wood pellets (net calorific value of 20.3 MJ/kg). Dried apple pomace contained 11.9% of pectin. Fed-batch cultivation of baker´s yeast with apple pomace extract demonstrated a potential for partial substitution of molasses in industrial bioprocesses. This concept shows how a zero discharge biorefinery process converts waste from apple juice production into three valuable products enabling connections between different industries