Optimisation of minimal media for production of aroma compounds typical for fermented milk products

U radu je optimirana minimalna podloga na bazi mlijeka i laktoze na kojoj bakterije mliječne kiseline mogu proizvesti maksimalnu količinu hlapivih aromatskih tvari karakterističnih za fermentirane mliječne proizvode. Za pripreme podloga korišten je kazein, tri-natrij-citrat, laktoza, mineralne tvari mlijeka, proteini sirutke i mlijeko s 1,5 % m.m. Glavna razlika pojedinih podloga bila je u količini citrata i proteina sirutke. Fermentacija je vođena pri sobnoj temperaturi do pH vrijednosti 5. Uzorci su senzorski ocijenjeni metodom kvantitativne deskriptivne analize. U svim podlogama željena pHvrijednost, ovisno o količini citrata, postignuta je nakon 68 - 71 sati fermentacije. Fermentacija i nastanak aromatskih tvari bili su intenzivniji u podlogama koje su sadržavale proteine sirutke u usporedbi s podlogama koje su sadržavale samo kazein. Povećana količina citrata u podlogama pozitivno je djelovala na razvoj arome u supstratu. Citrat je povisio početnu pHvrijednost podloge, ali i djelovao kao pufer tijekom fermentacije, zbog čega je bila moguća dulja fermentacija i veća sinteza aromatskih tvari. Pri pH vrijednosti oko 5, aroma karakteristična za fermentirane mliječne proizvode je bila najizraženija, a kiseli okus manje dominantan. Supstrat s 0,25% citrata i 0,1% proteina sirutke, pri pH-vrijednosti 5, imao je najbolje senzorske karakteristike.The aim of this research was to optimize the composition of minimal growth media containing lactose and milk, in which lactic acid bacteria (LAB) would produce the maximum amount of volatile aroma compounds typical for fermented milk products. Ingredients used for the preparation of media were casein, tri-sodium-citrate, lactose, milk minerals, whey proteins and milk with 1.5% fat. The several prepared media differed mainly in the amount of citrate and whey proteins. Fermentation was carried out at room temperature until the media reached pH value of 5. Samples were evaluated for sensory characteristics using quantitative descriptive analysis (QDA). In all media the target pH was reached after 68-71 hours of fermentation, depending on citrate level. Fermentation and the production of aroma compounds were more intensive in media that contained whey proteins compared to media with only casein. Increased citrate level had a positive influence on the aroma production. Citrate increased the initial pH of the media and acted as a buffer during fermentation, which lead to longer fermentation and prolonged production of aroma compounds. At pH around 5, the desired cultured aroma was the most intensive, whereas sour taste was less dominant. The substrate with 0.25% citrate and 0.1% whey proteins, at pH 5, was rated as best regarding its sensory characteristics

Reološka karakterizacija kompleksnih polisaharidnih smjesa

The objective this work was to rheologically characterise gravies and gels used in Whiskas© and Sheba© products. A few different testings were done. First, a few different hydrocolloids (xanthan, MCC, starch) were added in different concentrations to the basic gravy of chunk-in-gravy products and their rheological properties were measured. Second, the influence of chunks on gravy texture was tested using two different chunk types. Third, six products taken from the production line were tested on their batch to batch variability. Fourth, a competitor analysis was done, Mars products were analysed and compared with Nestle products. Fifth, the influence of starch on gel texture in chunk-in-gel products was tested. These analysis was done in order to better understand the rheological properties of gravies and gels in order to optimise recipes in future for maximum palatability.Cilj ovog rada je bio reološki karakterizirati umake i gelove koji se koriste u proizvodima Whiskas© i Sheba©. Nekoliko različitih testiranja su izvršena. Prvo, različiti hidrokoloidi (ksantan, MCC, škrob) su dodani u različitim koncentracijama u osnovni umak chunk-ingravy (komadi mesa-u-umaku) proizvoda i mjerena su njihova reološka svojstva. Drugo, testiran je utjecaj komada mesa na reološka svojstva umaka. Pri tome su korištene dvije različite vrste komada mesa. Treće, šest proizvoda su uzeti iz proizvodne linije te je testirana varijabilnost reoloških svojstava u različitim uzorcima tijekom proizvodnje. Četvrto, napravljena je analiza najvećeg konkurenta Nestle-a, reološki su analizirani proizvodi Marsa i uspoređeni s Nestleovim proizvodima. Peto, testiran je utjecaj škroba na teksturu gelova u chunk-in-gel (komadi mesa-u-gelu) proizvodima. Ove analize su napravljene kako bi bolje razumjeli reološka svojstva umaka i gelova te kako bi se u budućnosti recepti mogli optimizirati i dobiti maksimalna palatabilnost

Reološka karakterizacija kompleksnih polisaharidnih smjesa

The objective this work was to rheologically characterise gravies and gels used in Whiskas© and Sheba© products. A few different testings were done. First, a few different hydrocolloids (xanthan, MCC, starch) were added in different concentrations to the basic gravy of chunk-in-gravy products and their rheological properties were measured. Second, the influence of chunks on gravy texture was tested using two different chunk types. Third, six products taken from the production line were tested on their batch to batch variability. Fourth, a competitor analysis was done, Mars products were analysed and compared with Nestle products. Fifth, the influence of starch on gel texture in chunk-in-gel products was tested. These analysis was done in order to better understand the rheological properties of gravies and gels in order to optimise recipes in future for maximum palatability.Cilj ovog rada je bio reološki karakterizirati umake i gelove koji se koriste u proizvodima Whiskas© i Sheba©. Nekoliko različitih testiranja su izvršena. Prvo, različiti hidrokoloidi (ksantan, MCC, škrob) su dodani u različitim koncentracijama u osnovni umak chunk-ingravy (komadi mesa-u-umaku) proizvoda i mjerena su njihova reološka svojstva. Drugo, testiran je utjecaj komada mesa na reološka svojstva umaka. Pri tome su korištene dvije različite vrste komada mesa. Treće, šest proizvoda su uzeti iz proizvodne linije te je testirana varijabilnost reoloških svojstava u različitim uzorcima tijekom proizvodnje. Četvrto, napravljena je analiza najvećeg konkurenta Nestle-a, reološki su analizirani proizvodi Marsa i uspoređeni s Nestleovim proizvodima. Peto, testiran je utjecaj škroba na teksturu gelova u chunk-in-gel (komadi mesa-u-gelu) proizvodima. Ove analize su napravljene kako bi bolje razumjeli reološka svojstva umaka i gelova te kako bi se u budućnosti recepti mogli optimizirati i dobiti maksimalna palatabilnost