7. Quark

The fresh-cheese class — mesophilic LAB ferment, high casein protein, cornerstone of classic Central European cuisines.

Quark in 1 minute

What does it provide? The fresh-cheese class — milk fermented with mesophilic lactic acid bacteria (Lactococcus lactis subsp. lactis and cremoris), with the whey strained to concentrate protein. High casein protein (8–14 g/100 g depending on version), high calcium (≈ 90–150 mg/100 g), high phosphorus, high B12 (stable during fermentation), high live LAB (10⁶–10⁸ CFU/g in fresh traditional versions). Lower lactose (≈ 3–4 g/100 g) means many lactose-sensitive people tolerate it.

How much? 100–200 g/day plain, unsalted quark.

When to avoid? Cow's milk protein allergy (strictly); galactosemia (absolute); severe lactose intolerance (low, but sensitive individuals may still react); industrial pasteurized "quark-like" products (low LAB); ≥ 2 hours separation from levothyroxine, iron supplements; severe kidney disease (high protein + phosphorus); infant < 6 months.

Scientific Background

Quark belongs to the fresh cheese category (Codex Alimentarius: "fresh cheese," "acid-curd cheese"). Production process:

1. Starter: mesophilic LAB mix (Lactococcus lactis subsp. lactis, L. lactis subsp. cremoris, sometimes L. lactis subsp. diacetylactis for aroma).
2. Fermentation (12–24 hours at room temperature): pH around 4.4 — casein coagulates (isoelectric point). Small amount of rennet optional to speed up.
3. Whey straining: gravitational or mechanical on cheesecloth. Depending on the extent of whey straining, protein content is 8–14 g/100 g.
4. Packaging: fresh, refrigerated.

LAB content: classic small-batch fresh, non-pasteurized quark contains 10⁶–10⁸ CFU/g live LAB — EFSA claim valid (lactose digestion, as for yogurt).[1745] Industrial, longer-shelf-life products are pasteurized — low LAB, only postbiotic.

Nutrient matrix: casein is a slow-absorbing protein (vs. whey is fast) — overnight muscle protection, satiety. Casein-derived peptides (β-casomorphin, ACE-inhibitor peptides) have blood-pressure-reducing effects — Beltrán-Barrientos et al. (2016 J Dairy Sci 99:4099–4110), "Invited review: Fermented milk as antihypertensive functional food," details this mechanism.[1748]

Clinical studies: in the fresh cheese category (skyr, Greek yogurt, túró, quark), the high protein + calcium combination is favorable for bone health (Wallace 2018, Beltrán-Barrientos 2016) and metabolic profile.[1746] Hungarian population: traditional túró consumption partly compensates for lower vitamin D levels for bone health (calcium matrix).

Microbiome effect: Lactococcus lactis-dominant ferments provide a complex postbiotic matrix (bacteriocins, exopolysaccharides, peptides) — Bifidobacterium-elevating, anti-inflammatory. Marco et al. (2017) place fresh cheeses in the "Central European postbiotic + live LAB" category of fermented foods.[1676]

Quark vs. Túró: per European standards, "quark" tends to be lower-fat (often 0–10% fat), while Hungarian "túró" can be fattier (≈ 4–8% fat). Protein contents are similar. (Note: Codex Alimentarius CXS 273-1968 specifically covers cottage cheese; quark and túró fresh cheeses fall under the broader CXS 221-2001 "Group standard for unripened cheese including fresh cheese."[1750])

References

[1676] Marco ML et al. Health benefits of fermented foods: microbiota and beyond2017;44:94–102. Curr Opin Biotechnol. Link

Fermented foods and beverages were among the first processed food products consumed by humans. The production of foods such as yogurt and cultured milk, wine and beer, sauerkraut and kimchi, and fermented sausage were initially valued because of their improved shelf life, safety, and organoleptic properties. It is increasingly understood that fermented foods can also have enhanced nutritional and functional properties due to transformation of substrates and formation of bioactive or bioavailable end-products. Many fermented foods also contain living microorganisms of which some are genetically similar to strains used as probiotics. Although only a limited number of clinical studies on fermented foods have been performed, there is evidence that these foods provide health benefits well-beyond the starting food materials.

[1693] Sanlier N et al. Health benefits of fermented foods2019;59(3):506–527. Crit Rev Food Sci Nutr. Link

In the past, the beneficial effects of fermented foods on health were unknown, and so people primarily used fermentation to preserve foods, enhance shelf life, and improve flavour. Fermented foods became an important part of the diet in many cultures, and over time fermentation has been associated with many health benefits. Because of this, the fermentation process and the resulting fermented products have recently attracted scientific interest. In addition, microorganisms contributing to the fermentation process have recently been associated with many health benefits, and so these microorganisms have become another focus of attention. Lactic acid bacteria (LAB) have been some of the most studied microorganisms. During fermentation, these bacteria synthesize vitamins and minerals, produce biologically active peptides with enzymes such as proteinase and peptidase, and remove some non-nutrients.

[1745] EFSA NDA Panel. Scientific opinion on live yoghurt cultures and improved lactose digestion2010;8(10):1763. EFSA Journal. Link

EFSA NDA Panel opinion under Article 13(1) (claims ID 1143, 2976): based on the submitted human studies the Panel established a cause-and-effect relationship between consumption of live yoghurt cultures (L. delbrueckii subsp. bulgaricus and S. thermophilus) and improved digestion of lactose in yoghurt among lactose maldigesters. To obtain the effect the yoghurt should contain at least 10^8 CFU live starter bacteria per gram.

[1746] Wallace TC. Health effects of fermented dairy 2018. J Food Sci. 2018.

Review of the health effects of fermented dairy products.

[1748] Beltrán-Barrientos LM, Hernández-Mendoza A, Torres-Llanez MJ, González-Córdova AF, Vallejo-Córdoba B. Invited review: Fermented milk as antihypertensive functional food2016;99(6):4099–4110. J Dairy Sci. Link

Over the past decade, interest has risen in fermented dairy foods that promote health and could prevent diseases such as hypertension. This biological effect has mainly been attributed to bioactive peptides encrypted within dairy proteins that can be released during fermentation with specific lactic acid bacteria or during gastrointestinal digestion. The most studied bioactive peptides derived from dairy proteins are antihypertensive peptides; however, a need exists to review the different studies dealing with the evaluation of antihypertensive fermented milk before a health claim may be associated with the product. Thus, the objective of this overview was to present available information related to the evaluation of fermented milk containing antihypertensive peptides by in vitro and in vivo studies, which are required before a fermented functional dairy product may be introduced to the market. Although commercial fermented milks with antihypertensive effects exist, these are scarce and most are based on Lactobacillus helveticus. Thus, a great opportunity is available for the development of functional dairy products with new lactic acid bacteria that support heart health through blood pressure- and heart rate-lowering effects.

[1750] Codex Alimentarius. Group standard for unripened cheese including fresh cheese (CXS 221-2001). . 2001. Link

Codex Alimentarius group standard for unripened cheese, including fresh cheese (CXS 221-2001).

[1751] Hill C et al. ISAPP consensus on the term "probiotic"2014;11(8):506–514. Nat Rev Gastroenterol Hepatol. 2014. Link

An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics. It is now 13 years since the definition of probiotics and 12 years after guidelines were published for regulators, scientists and industry by the Food and Agriculture Organization of the United Nations and the WHO (FAO/WHO). The FAO/WHO definition of a probiotic--"live microorganisms which when administered in adequate amounts confer a health benefit on the host"--was reinforced as relevant and sufficiently accommodating for current and anticipated applications. However, inconsistencies between the FAO/WHO Expert Consultation Report and the FAO/WHO Guidelines were clarified to take into account advances in science and applications. A more precise use of the term 'probiotic' will be useful to guide clinicians and consumers in differentiating the diverse products on the market. This document represents the conclusions of the ISAPP consensus meeting on the appropriate use and scope of the term probiotic.

[1752] Lordan R et al. Dairy fats and cardiovascular disease: do we really need to be concerned?2018;7(3):29. Foods. 2018. Link

Cardiovascular diseases (CVD) remain a major cause of death and morbidity globally and diet plays a crucial role in the disease prevention and pathology. The negative perception of dairy fats stems from the effort to reduce dietary saturated fatty acid (SFA) intake due to their association with increased cholesterol levels upon consumption and the increased risk of CVD development. Institutions that set dietary guidelines have approached dairy products with negative bias and used poor scientific data in the past. As a result, the consumption of dairy products was considered detrimental to our cardiovascular health. In western societies, dietary trends indicate that generally there is a reduction of full-fat dairy product consumption and increased low-fat dairy consumption. However, recent research and meta-analyses have demonstrated the benefits of full-fat dairy consumption, based on higher bioavailability of high-value nutrients and anti-inflammatory properties.