Sporedni proizvodi vinske industrije kao izvor bioaktivnih jedinjenja: karakterizacija i mogućnost primene u prehrambenoj industriji

Abstract

U okviru ove doktorske disertacije su okarakterisana fenolna jedinjenja pokožice i semenke izdvojene iz nefermentisane komine internacionalnih i autohtonih sorti grožđa, kao i fermentisane komine vinske sorte Prokupac. Dijetna vlakna, šećeri i masne kiseline u semenkama komine grožđa su dodatno okarakterisani. Odabrani ekstrakti fenolnih jedinjenja su korišćeni u formulaciji funkcionalnih aditiva na bazi proteina kozijeg mleka i kozijih jogurata dobijenih korišćenjem starter kultura i selekcionisanog Lactobacillus plantarum soja. Utvrđen je efekat matriksa hrane (meso/žitarice, proteini kozijeg mleka, dijetna vlakna (inulin), proteini mleka/dijetna vlakna), na biodostupnost fenolnih jedinjenja iz pokožice i semenki grožđa nakon in vitro digestije. Za postizanje ovih ciljeva koriščene su: spektrofotometrijske, kuplovane hromatografske, elektroforetske i DNK-zasnovane tehnike, zajedno sa spektroskopskim, fizičko-hemijskim i biohemijskim analizama. Brašna semenki izdvojenih iz nefermentisane komine dobar su izvor nerastvornih/ukupnih dijetnih vlakana, zaostalih šećera (glukoza i fruktoza) i nutritivno vrednih masnih kiselina (linolne i oleinske kiseline). Procijanidini i katehin su dominantna fenolna jedinjenja u semenkama, dok su u pokožicama najzastupljeniji flavonoli, kao i malvidin i peonidin derivati iz klase antocijana. Liofilizacija fermentisane komine Prokupca i njenih konstituenata ima neznatan uticaj na sadržaj dominatnih fenolnih jednjenja koja su ispoljila dobra antioksidativna svojstva. Ekstrakt pokožice pokazao je ćelijsku antioksidativnu aktivnost na humanim ćelijama kolorektalnog adenokarcinoma, dok se ekstrakt liofilisane peteljke pokazao kao dobar izvor stilbenoida. Dodatkom ekstrakta semenki grožđa i inulin/ekstrakt praha u termički tretirano kozije mleko utvrđeno je prisustvo polifenol-protein interakcija, prvenstveno procijanidina sa serum protein/kazein kompleksima. Dobijeni funkcionalni aditivi su pokazali dobra antioksidativna svojstva, dok su 0,1% rastvori pokazali dobra emulgujuća i loša peniva svojstva. Predloženi su modeli distribucije fenolnih jedinjenja između serum i micelarne faze kozijeg mleka, kao i distribucije kazeinskih micela na međufazama ulje/voda i vazduh/voda u emulzijama i penama formiranim od odabranih funkcionalnih aditiva. Jogurt od kozijeg mleka sa dodatim ekstraktom semenki grožđa, fermentisan starter kulturom i L.plantarumom, je pokazao dobra teksturna i senzorna svojstva. Ovaj liofilisani jogurt je pokazao bolja antioksidativna i emulgujuća svojstva u poređenju sa drugim liofilisanim jogurtima. Svi liofilisani jogurti, koji su fermentisani sa L.plantarum-om, pokazali su visoku vijabilnost ćelija (>108 CFU/g SM). Biodostupnost fenolnih jedinjenja iz pokožice i semenki grožđa nakon in vitro digestije bila je različita i zavisna od sastava matriksa, i kretala se od 6,03% za matriks kozije mleko/inulin do 50.9% za matriks meso/žitarice, dok su proteini rastvorljivih frakcija digestovanih funkcionalnih aditiva bili potpuno hidrolizovani nakon in vitro gastrointestinalne digestije. Digestovani funkcionalni aditivi pokazali su smanjena (osim kod meso/žitarice matriksa) antioksidativna svojstva u odnosu na nedigestovane uzorke, što je bilo u korelaciji sa smanjenom biodostupnoću fenolnih jedinjenja. Na osnovu dobijenih rezultat može se zaključiti da komina vinske sorte Prokupac i njeni konstituenati, mogu biti jeftin izvor fenolnih jedinjenja pogodnih za razvoj funkcionalnih prehrambenih proizvoda, dok njeno korišćenje istovremeneo omogućava zaštitu životne sredine.

The aim of this doctoral dissertation was characterisation of phenolic compounds of skins and seeds separated from non-fermented pomace of international and indigenous grape varieties, as well as phenolic profiles of fermented pomace of the Prokupac grape variety. Dietary fiber, sugars, and fatty acids from grape pomace seed extracts were also characterized. Selected phenolic extracts were used in the formulation of functional additives based on goat milk protein and goat yogurts produced with the utilisation of starter culture and selected Lactobacillus plantarum strain. The effect of food matrices (meat/cereal, goat's milk protein, dietary fiber (inulin), goat’s milk protein/dietary fiber) on the bioaccessibility of phenolic compounds from skin and grape seeds after in vitro digestion was evaluated. Spectrophotometric, coupled chromatographic, electrophoretic, and DNA-based techniques together with spectroscopy, physicochemical and biochemical analyses were used to achieve these aims. Grape seed flours of non-fermented pomaces are a good source of insoluble/total dietary fiber, residual sugars (glucose and fructose), and nutritionally valuable fatty acids (linoleic and oleic acids). Procyanidins and catechin were dominant in the seeds, while flavonols, malvidin and peonidin derivatives were the most common phenolic compounds in the skins. Lyophilization of fermented Prokupac pomace and its constituents has a slight effect on the dominant phenolic compounds that showed good antioxidant properties. The skin extract exerted cellular antioxidant activity on adenocarcinoma cells, while extract of lyophilized pomace stems showed as a good source of stilbenoids. After the addition of seed extract and inulin/extract powder to thermally treated goat milk, the presence of polyphenol-protein interactions were recorded, primarily procyanidin with serum protein/caseins (WP/CN) complex. Furthermore, obtained functional additives showed good antioxidant properties, whereas 0.1% solutions showed good emulsifying properties but poor foaming techno-functional properties. Models of phenolic compounds distribution between serum and micellar phases in thermally treated goat milk, as well as the distribution of casein micelles at the oil/water and air/water interfaces in emulsions and foams of selected functional additives were proposed. Goat yogurt with seed extract fermented with starter culture and L. plantarum showed good textural and sensory properties. This lyophilized yogurt showed better antioxidant and emulsifying properties compared to other lyophilised yoghurts. All lyophilized yoghurts, fermented with L.plantarum, showed high cell viability (>108 CFU/g SM). The bioaccessibility of individual phenolic compounds from grape skins and seeds were different and dependent on the composition of the food matrix. The bioaccessibility ranged from 6.03% for goat milk/inulin matrix to 50.9% for meat/cereals matrix, whereas soluble protein fractions of digested functional additives were completely hydrolyzed after in vitro gastrointestinal digestion. The digested samples showed reduced (except for meat/cereal matrix) antioxidant properties compared to their undigested samples, which were related to the reduced bioaccessibility of phenolic compounds. Based on the obtained results it can be concluded that grape pomace of the Prokupac variety can be a cheap source of phenolic compounds suitable for the development of functional food products, while its utilisation allows, at the same time, enviroment protection.