SMEN OR SAMN
Smen manufacturing is a classical method of fat preservation dating back to early civilisations in the south asia and Africa. This method is applied successfully to preserve butter from spoilage and also to enhance its organoleptic and nutritional quality. Smen is another dairy product modelled on butter rather than on the entire curd (like cheese).
The use of smen in many culinary preparations make people enjoy its pleasant and agreeable flavour and aroma. It is also consumed as fat by the rural population during the season of butter shortness (winter), and imitated for its organoleptic and gustatory properties.
Smen is a Moroccan edible fat (fermented butter) known and preferred to other dairy products for its subsequent flavour and aroma. Smen is made from raw butter as follow:
In Morocco traditional butter is prepared by farmer mainly during the high milk production season (April-July). Raw milk is allowed to ferment spontaneously until it reached 0.8 to 1 % acidity (as lactic acid) and churned in a goat skin bag until butter separate. Butter is then gathered inside the bag by hand and extracted from “lben” (the remaining liquid).
The resulting butter possess specific gustatory characteristics that make it enjoyed by the consumers, so the price is twice that of the usual butter (processed butter). The daily production of traditional butter by the farmers cannot be consumed immediately, so the exceeding amounts are collected and transformed into smen by salting, and conditioning in earthen-ware jars as described. The salted butter is stored until the characteristic flavour of smen appear.
The traditional Moroccan butter is generally processed from cow milk, but goat, sheep or camel milk, or even a mixture of two of these milks can be used. Milk is allowed to ferment spontaneously for 24 to 48 h at about 18-24øC, depending on the season. The curd obtained after coagulation is churned in a goatskin bag (chekoua) which is shaken vigorously to and fro or agitated in an earthenware jar with a wooden instrument consisting of a handle with two discs of different diameters at one end. At the end of churning, warm water, and then cold water may be added to improve butter formation. Addition of water must not exceed 10 % of milk volume, to avoid dilution of lben nutrients and consequently a decrease in its nutritional value. After churning and removal of the butter, the remaining liquid is called leben.
Most producers gather the butter with their hands, although some prefer to filter the lben with a piece of cotton sheet to retrieve more of the butter.
Traditional butter is collected on several churnings because of the small amounts of milk churned by the traditional procedure. The collected amount of butter (5 to 10 kg) is washed to remove the remaining lben and also to eliminate from the aqueous phase most of the nutrients that could help in microbial growth and thus to enable the smen to be stored for a longer time. Warm water is used first, followed by slightly salted water.
Dry salt is used for salting. This operation is difficult because it is necessary to homogenize the salt and the butter. The salt is generally added progressively, while the butter is worked continuously; the overall amount is about 100-120 g salt per kg of butter.
In some regions salt is solubilized in water and butter is well malaxed in the salted water.
The butter is then introduced into earthenware pots which are filled carefully to avoid incorporating air within the butter; otherwise, undesirable oxidation may occur. The pots are hermetically closed and stored in a cool dark room. After four to six months, the salted butter has generally matured into smen. However, storage may need to be longer.
Thus, smen processing is characterized by specific conditions: (a) no heat treatment; (b) salting as of the product; (c) storage at room temperature and under anaerobic conditions.
CHEMISTRY OF TRADITIONAL SMEN
The average values of the fat, water and non-fat dry matter are respectively: 81.3, 13.7 and 5.0 %. However, the values vary widely among the samples. In the aqueous phase, the average amount of chloride is 8%, while lactose and protein do not exceed 3.2 and 1.2 %, respectively. The small concentrations of organic compounds are related to: (a) their microbial degradation; (b) their washing-out during smen processing; and (c) water exudation during storage.
Data of table 2 showed the physico-chemicl patterns of traditional smen. The pH values range from 3.4 to 3.9 and the aw was found to be low in this product relatively to the same food systems modelled on milk. No significant variation was observed among smen made by different makers for both pH and aw, with a standard deviation of 0.5 for the former and 0.04 for the later.
The ADVs (Acid Degree Values) of smen were found to be expectedly high. The reached levels may occur as a result of the chemical breakdown of butter’s triglycerides leading to FFA profiles increase and consequently to a considerable pH slow down. The average ADV was 54.29, with significant variation among the values obtained, the standard deviation was high (10.54).
Differences observed among the samples for the ADV are due mainly to the conditions related to the raw matter and to maker. In the first case the raw butter (traditional butter) vary widely from one maker to another. It is extracted and washed manually so, variations in the moisture, the solid non fat and also to the sanitation of the environment. Some samples could retain more lactose or lactic acid, some others may have high contents in solid non fat as precipitated casein etc.
The oxidation of smen is very small (70 % of commercial smen samples showed a peroxide index below 3 meq/kg of fat) in spite of the acidity and the salt which favour oxidation. However, the smen storage in hermetic conditions and darkness could explain this small amount of oxidation.
The oxidative reactions are prevented in smen by the environmental conditions. This is du to the low peroxide index. In the traditional procedure, smen is conditionned in earthen-ware jars which are well filled and pressed to drive out the air. The fat oxidation is also prevented by the presence of some plants (thyme) which may have probably some antioxydant properties. We hope to tell more about those phenomena.
The low aw is probably related to the salt addition in the product by the makers. The added salt may Concentrate in the aqueous portion and reach a high level sufficient enough to cause the aw slow down. The aqueous portion of smen is relatively lower than the fatty portion, it ranges from 10 to 20 % of the product. According to the same authors the sodium chloride concentrations range from 3.4 to 19.3 expressed as percent of non fat.
Free Fatty Acids (FFA)
Data which involve the FFA profiles are reported in table 3. As can be seen, all samples showed high FFA contents relatively to the other dairy products (butter cream, cheese…). The volatile FFA (C4 to C12) respectively butyric, caproic, caprylic, capric and lauric acid which are responsable for the flavour of smen are present in low concentrations compared to intermediate and long chain FFA. The major acids in smen were myristic (C14), palmitic (C16) and the unsaturated oleic (C18:1).
It is clear that the high FFA levels reached in smen are in relation with the pH decrease. It should be enphasized here that the occurrence of lipolysis as the major biochemical breakdown during the manufacture of this product may result in large FFAamounts. The free fatty acids may accumulate in smen as end products of the lipolytic reaction since they are not involved in other biochemical breakdown pathways like in cheese where the volatile monocarbonyles arise from FFA breakdown. Morever, the acidity cannot be alleviated by other basic compounds originated from protein hydrolysis.
MICROBIOLOGY OF SMEN
The results dealing with smen microbiology are due to Faid et al (1990). Apart from the lactobacilli and the yeasts and moulds, the microflora of smen is small. This cannot be due to the salt effect alone. The absence or the small number of some microorganisms is probably linked to the free fatty acid accumulation and the total or partial disappearance of nutrients (lactose, proteins, mineral salts) in the aqueous phase. Theses conditions are responsible for the total absence of enterobacteria and coliforms and presumably enterotoxigenic staphylococci and Salmonella. Hence, smen is a safe food.