Truffle (Tuber sp.): microflora, aromatic compounds and application in cheese production

[D. D. Paunović]

118 str.

Tehnološko inženjerstvo - Tehnološka mikrobiologija / Technological Engineering - Industrial Microbiology

Tartufi su podzemne mikorizne gljive, veoma cenjene zbog specifične arome, koja velikim delom nastaju kao proizvodi metabolizma mikroorganizama rizosfere, kao što su bakterije, kvasci i filamentozne gljive. S obzirom da se aroma tartufa gubi tokom čuvanja, neophodno je naći tehnike očuvanja arome u dužem periodu, kako bi se tartufi mogli koristiti i van sezone njihovog pronalaženja. Kako je tartuf prirodan proizvod sa izuzetnim nutritivnim i funkcionalnim svojstvima, krajnji cilj ovog rada je bio dobijanje novog multifunkcionalnog prirodnog i nutritivno vrednog proizvoda, u ovom slučaju polutvrdog sira sa dodatkom tartufa i potencijalnog autohtonog probiotika Lactobacillus plantarum 564, bez dodavanja veštačkih aroma. Jedan od ciljeva ovog rada je bio izolacija mikrobiote tartufa i njena identifikacija, kao jednog od faktora produkcije arome tartufa, pri čemu je utvrđeno prisustvo bakterija, kvasaca, aktinomiceta i gljiva. Većinu prisutnih mikroorganizama su činile bakterije, gde su najzastupljenije vrste roda Bacillus sp. (62,5%). Zatim je ispitano očuvanje aromatičnih materija samih tartufa, nakon liofilizacije i režima zamrzavanja tartufa na -20°C i -80°C, sa i bez primene tečnog azota u toku skladištenja od 90 dana. U cilju očuvanja arome, utvrđen je najoptimalniji tretman dekontaminacije za primenu tartufa u hrani, a na osnovu dobijenih rezultata odabrani su režimi flambiranja i autoklaviranja tartufa svežih i smrznutih na -20°C za primenu u proizvodnji četiri varijante sireva. Osim navedenih varijanti proizvedene su i dve varijante, jedna kontrolna bez dodavanja tartufa i druga sa dodatkom veštačke arome, kako bi se mogao porediti senzorni kvalitet dobijenih sireva tokom 90 dana zrenja. Tokom zrenja sireva je utvrđeno da sirevi sa flambiranim smrznutim tartufima imaju ubrzano zrenje, veći koeficijent zrelosti, broj prisutnih startera i potencijalnih probiotika veći za 1 log jedinicu u odnosu na kontrolni sir. Sastav aromatičnih materija sireva je obuhvatao 35 jedinjenja, koja su svrstana u jedinjenja sa sumporom, aldehide, ketone i alkohole. Utvrđeno je da su ketoni najzastupljeniji kod varijanti sireva sa svežim i zamrznutim flambiranim tartufima, dok sumporna jedinjenja nisu detektovana. Sadržaj 2,3-butandiona, 2-pentanona, 2-heptanona i 3-oktanona u sirevima sa flambiranim tartufima je bio najveći, a sadržaj 2-butanona u siru sa smrznutim flambiranim tartufom, je bio deset puta veći u odnosu na kontrolni sir. U ukupnom sadržaju aldehida u sirevima od 90 dana, utvrđen je najveći relativni udeo 2-metil-butanala, 3-metil-butanala, acetaldehida i 2- metil-propanala u varijantama sireva sa smrznutim flambiranim tartufima. Alkoholi važni za aromu tartufa, 2-butanol, 2-metil-butanol i 1-okten-3-ol, koji su se pojavljivali u sirevima, su najviše zastupljeni kod sireva sa flambiranim tartufima, pri čemu je 2-butanol bio zastupljeniji kod sira sa smrznutim flambiranim tartufom. Senzornom analizom je utvrđeno da su najbolje ocenjeni kontrolni sir i sirevi sa tartufima dodatim nakon flambiranja, pre zamrzavanja ili nakon 90 dana čuvanja u smrznutom stanju na -20°C. Ovi sirevi su ocenjeni kao sirevi visokog kvaliteta sa ocenama 95,41% i 98,08% od maksimalnog kvaliteta, što ih svrstava u grupu odličnih sireva. Najniže ocene u pogledu mirisa i ukusa, imao je sir proizveden uz dodatak veštačke arome. Ovim radom je postignut cilj pronalaženja optimalnog načina zamrzavanja tartufa i inkorporacije u sir, obogaćenog autohtonim potencijalnim probiotikom u cilju dobijanja inovativnog prirodnog prehrambenog proizvoda bez dodavanja veštačke arome.

Truffles are underground mycorrhizal fungi, highly valued for their specific aroma, which are largely formed as products of metabolism of microorganisms of the rhizosphere such as bacteria, yeasts and filamentous fungi. Since the aroma of truffles is lost during storage, it is necessary to find techniques for preserving the aroma for a longer period of time, so that truffles can be used outside the season of finding them. As truffle is a natural product with exceptional nutritional and functional properties, the ultimate goal of this work was to obtain a new multifunctional natural and nutritionally valuable product, in this case semi-hard cheese, with added truffles and potential autochthonous probiotic Lactobacillus plantarum 564, without adding artificial flavors. One of the goals of this work was the isolation and identification of the truffle microbite, as one of the factors in the production of truffle aroma, during which the presence of bacteria, yeasts, actinomycetes and fungi was determined. Isolated microorganisms mainly were bacteria, where the most common species was genus Bacillus sp. (62.5%). Then, the preservation of aromatic substances of the truffles was examined after lyophilization and freezing regime at -20°C and -80°C with and without the application of liquid nitrogen during 90 days of storage. In order to preserve the truffle aroma, the most optimal way of truffles decontamination for application in food production was determined, and based on the obtained results, the regimes of flambing and autoclaving of fresh and frozen truffles at -20°C were selected for application in the 4 variants cheese production. Beside the above mentioneted four variants of cheese, two more variants were produced, one control without the addition of truffles and the other with the addition of artificial flavor, in order to compare the sensory quality of the obtained cheeses during 90 days of cheese ripening. During cheese ripening, it was determined that cheeses with flambed frozen truffles had accelerated ripening, had higher ripening coefficient, number of starter culture bacteria and potential probiotics higher by 1 log unit, compared to control cheese. The composition of the aromatic substances of the cheeses included 35 compounds, which are classified as sulfur compounds, aldehydes, ketones and alcohols. Ketone compounds were most abundant in cheese variants with fresh and frozen flambed truffles, while sulfur compounds were not detected. The content of 2,3-butanedione, 2-pentanone, 2-heptanone and 3-octanone in cheeses with flambed truffles was the highest, and the content of 2- butanone in cheese with frozen flambed truffles was ten times higher than in the control cheese. For aldehydes content in 90-day in cheeses, the highest relative share of 2-methyl-butanal, 3-methylbutanal, acetaldehyde and 2-methyl-propanal was determined in cheese variants with frozen flambed truffles. Alcohols which are important for the aroma of truffles, like2-butanol, 2-methylbutanol and 1-octen-3-ol were most present in cheeses with flambed truffles, while 2-butanol had the higest concentration in cheeses with frozen flambed truffles. Sensory evaluation determined that the best evaluated cheeses were control cheese and cheeses with truffles added after flambing either before or after 90 days of storage in the frozen state at -20°C. These cheeses were evaluated as cheeses of high quality with the marks 95.41% and 98.08% of the highest possible quality, which classifies them as excellent cheeses. The cheese with the addition of artificial aroma had the lowest marks in terms of smell and taste. This work achieved the goal of finding the optimal way to freeze truffles and incorporate them into cheese, enriched with autochthonous potential probiotics in order to obtain an innovative natural food product without adding artificial flavor.

tartufi, aromatične materije, sir, autohtoni potencijalni probiotici

truffles, aromatic compounds, cheese, autochthonous potential probiotics

637.35:579.6(043.3)

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