Investigation of a Quark Production Process

Abstract

Quark is a dairy product that has existed for a long time. However, it has grown
in popularity during the last years due to the fact that it is often portrayed as
a healthy alternative in the dairy section. There are no regulations connected to
the manufacturing process of quark. At a specific dairy company, there is a desire
to understand and optimise the quark production to obtain a consistently better-tasting product with good texture. To meet this wish, three different approaches were used. The first focus was to investigate if there were large variations in the time spent by the quark in the fermentation tank. The second focus was to find out if there were milk proteins present in the whey obtained during quark separation. Finally, the third focus was to investigate the impact of rennet and thermisation on the product. The average time spent in the fermentation tank was 23 hours however, some batches spent up to 50 hours before being exposed to the subsequent thermisation step. This could possibly lead to the development of a bitter taste in the product as a consequence of the proteolytic activity of the rennet (Sohal, Roehl, and Jelen 1998). Moreover, excluding rennet from production lead to larger particle sizes in the quark which could negatively impact the mouthfeel. The protein composition in the whey also changed as a consequence of excluding rennet and thermisation. In all cases however, the whey fraction contained both caseins and whey proteins. More production runs excluding rennet and thermisation could be conducted to obtain reproducible results. The factors resulting in extended fermentation times could be identified and eliminated. Finally, the option of recovering the proteins in the whey through ultra- or nanofiltration could be investigated.

Popular Abstract

Quark is a relatively new product in the dairy section in Sweden. It has an appearance similar to yoghurt but is often a bit thicker in consistency and has a higher protein content. Other than that, it is difficult to define what it really is. To make it a bit more confusing, the way of producing quark differs depending on which company one looks at. Besides creating a lot of questions, this also creates a lot of opportunities for the dairy companies to find the best recipe and manufacturing process possible to create the best product on the market.

At a specific dairy company, there was a desire to better understand and optimise
the quark production process with an underlying wish to obtain a better-tasting
product.

Traditionally, rennet is used as an ingredient in quark. This is what is added to
milk used to produce cheese, it causes milk to coagulate. In quark production, only
a small amount of rennet is added as it is not the only factor causing coagulation.
At the above-mentioned dairy company, it is suspected that rennet sometimes gives
the quark an undesired bitter taste. So then why is rennet added since there are
other factors causing coagulation of the milk? That is one of the questions this work aimed towards answering.

To do this, a batch of quark was produced without the addition of rennet. Another
batch excluding rennet was also produced, but this batch also lacked a production
step called thermisation. The aim of the thermisation was to make the rennet
inactive, so this step was possibly not needed when rennet was excluded. Samples
taken from these two batches, together with samples from a regular quark production
run, were analysed in many ways to see if there were differences between them. As
it turned out, the particles in the quark excluding rennet were larger than in the
regular quark. From a sensory test, it was also concluded that it was possible to
distinguish between the three quark products by appearance and taste.

Moreover, as a step towards better understanding the quark production process, it
was concluded that the time spent by the quark in the fermentation tank should
be closely monitored as there were quite large time variations between production
batches. This is the production step during which rennet is active and a long fermentation time could be the reason for why there were sometimes a hint of bitterness in the taste of quark.

At this point, many questions still remain but in the future, a sensory evaluation
investigating whether the quark produced without rennet was different from regular
quark in a positive or negative way should be made. One can hope that the removal
of rennet resolves all questions by being the best tasting quark product on the
market.

• author: Sandberg Blixth, Ebba
• supervisor: Maria Glantz; Frida Lewerentz
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLGM10 20212
• year: 2022
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Dairy, food technology, quark, fermentation
• language: English
• id: 9095883
• date added to LUP: 2022-08-02 10:11:08
• date last changed: 2022-08-02 10:11:08