Fermented milk products are important staples in Southern Mediterranean countries. They are produced through spontaneous or back-slopping fermentation of milk from cows, goats, ewes, sheep, camels, or buffalo, depending on the country’s livestock farming. Spontaneous fermentation consists of the “natural” fermentation of raw milk for hours to days at room temperature. This fermentation is mediated by indigenous microflora, especially lactic acid bacteria and exogenous micro-organisms (contamination) [17]. Even though the fermentation process was studied for years, the naturally occurring bacteria had not yet been fully deciphered until now. Spontaneously fermented milk products can serve as a model system for investigating microbial ecology and evolutionary adaptations [11]. However, the main concerns over natural milk fermentation are associated with the high initial contamination [18], the inadequate hygiene conditions during the artisanal process [5,19], and the absence of any thermal treatment [9,20]. Back-slopping is another “natural” fermentation process that consists of adding a small quantity of old fermented product (yogurt or cheese) as a fermentate into a fresh raw ingredient [21]. The repetition of the identical back-slopping fermentation process stabilizes the microbial community and standardizes the quality and safety of the final product [11,22].
1. Drinking Yogurt
Spontaneously fermented milk, Raib or Rayeb, is produced in many Southern Mediterranean countries [
37,
38]. Traditionally, raw milks are spontaneously fermented at room temperature until coagulation [
27,
28]. Fermentation has been associated with bacteria (e.g.,
Lactococcus lactis and
Leuconostoc mesenteroides) and yeast (e.g.,
Saccharomyces and
Candida) naturally occurring in raw milks [
39,
40]. These micro-organisms are responsible for milk acidification, texture change, and aromatization [
39]. They are natural probiotics providing several health benefits, such as improving immune system, the blood lipidic profile, and intestinal health [
41]. Fermented milk could be consumed directly after fermentation or after manually skimming [
42].
Buttermilk (“Lben” in Morocco and Algeria, “leben” in Tunisia, and “Iraqi” or “Laban Khad” in Egypt) is made through the spontaneous fermentation of raw milk at room temperature (24–72 h) until coagulation [
45]. The spontaneously fermented milk is churned to separate nonbutter fraction from the butter [
46]. Lactic bacteria identified in traditional buttermilk belong to
Lactococcus lactis,
Leuconostoc mesenteroides, and
Lactobaccillus plantarum species. The key aromatic compounds are mainly butanoic acid, acetoin, and hexanoic acid [
47]. Even though buttermilk is generally considered safe for consumption, pathogenic micro-organisms (e.g.,
Escerichia coli,
Salmonella enteritidis and
Staphylococcus aureus) have been detected [
15]. Laban in Lebanon or Laban Zabady in Egypt is a spoonable yogurt obtained by back-slopping fermentation. A small quantity of old Laban is used as a starter and added to pasteurized milk. Micro-organisms identified in Laban are
Streptococcus termophilus,
Leuconostoc lactis, and
Lactobacillus acidophilis [
30].
2. Spoonable Yogurt
Labneh or Shaneenah is a sour and creamy product heavily consumed in the Mediterranean region (Lebanon, Egypt, Jordan, and Syria) [
34,
35,
36] and commercialized worldwide. It is obtained by draining Laban or Zabady by using a cheesecloth at room temperature until obtaining the desired solid texture. Labneh is characterized by high-protein (double the content of Laban) and probiotic micro-organisms (more concentrated in viable lactic acid bacteria than yogurt) contents and low-lactose content [
51]. Moreover, it has a fat content of 9–11% (if full-fat yogurt is used), a moisture content of around 75%, a pH of around 4.5 and a shelf life of 7 to 10 days [
35]. A unique version of Lebanese Labneh, known as Labneh Anbaris, Labnet el-jarra, and Serdaleh, was produced mainly in the rural areas. It is obtained by spontaneously fermenting milks with 5% coarse salt for two weeks [
52]. Fermentation takes place in specific earthenware jars with holes designed for continuous whey drainage. Jars are refilled with fresh milk at around 30 ℃ every 5–7 days until the jars are full. Fresh Labneh Anbaris has a firm texture, white color, and high acidic content (pH 3.76) [
53]. It is consumed fresh or shaped into small balls and conserved in glass jars filled with olive oil for up to one year.
Kishk is widely consumed in Lebanon, Jordan, Egypt, Palestine, and Syria [
32]. It is known by different names: keshek, Kishk (Lebanon), kushk, or Kishk Matrouh (Egypt). Kishk is prepared by mixing cereal such as burghul (crushed and parboiled wheat), wheat, or barley with fermented milk (Laban (Lebanon) or buttermilk (Egypt)] from milk in a ratio of (1:1–1:4) and salt (3%) [
32,
33,
54]). The fermentation could take a few days (2 to 7 days) at room temperature, with a daily addition of fermented milk to keep the fermentation active. The obtained paste is kneaded, shaped into balls, and consumed fresh or preserved in glass jars filled with olive oil. Kishk balls also could be sundried, and then rubbed by hand to obtain Kishk flour with a long shelf life (1 to 2 years) [
33]. Kishk flour is characterized by a fat content of 8–10%, low moisture content (10–15%), pungent acidic taste, and low pH (3.80–4.80) [
32,
55]. Kishk flour was used as an ingredient to make nutritionally balanced (high in protein and fiber) soups [
33].
This entry is adapted from the peer-reviewed paper 10.3390/fermentation8120743
