IE43986B1 - Method of preparing aromatic soured butter - Google Patents

Abstract

1516786 Aromatic butter STICHTING BEDRIJVEN VAN HET NEDERLANDS INSTITUUT VOOR ZUIVELONDERZOEK 18 Nov 1976 [18 Nov 1975] 48193/76 Heading C5C Aromatic soured butter is made by (a) churning a non-soured cream having a fat content of 15-75 weight percent at 5 to 20‹C to obtain butter and sweet buttermilk, (b) draining off the buttermilk and (c) kneading into the butter an aromatic starter produced by culturing Streptococcus diacetilactus on a low fat milk product and up to 2 weight per cent, based on the butter, of a non-aromatic acid concentrate, produced by culturing Lactobacillus Helveticus on a low fat milk product, to form butter the serum of which has a pH # 5À5.

Description

The present invention relates to a method of preparing aromatic soured butter from non-soured cream.

It is known to prepare butter by churning either 5 soured or non soured (sweet) cream, whereby there is formed as a by-product a large quantity of buttermilk, which is sour when the starting material is sour cream and sweet when the starting material i s sweet cream.

Buttermilk contains a high proportion of 10 nutrients and it is therefore desirable that the butter milk be worked up to recover these nutrients in a useful form. Although this is technically feasible in the case of sour buttermilk, it is expensive - the cost of the working up is often greater thah the market value of the resulting product. It is considerably cheaper to convert sweet buttermilk into a useful product, so that it is economically advantageous to prepare butter from sweet cream.

However, butter made from sweet cream lacks the typical fresh aromatic flavour of butter made from soured cream and is less resistant to microbial attack.

The preparation of butter by churning bacterially soured cream also has disadvantageous in that temperature conditioning is necessary to produce butter having optimum organoleptic and rheological characteristics. 43880 - 3 However the temperature needed for optimum organoleptic characteristics is often widely different to that needed for optimum rheological characteristics so that the resulting butter often has organoleptic defects in flavour, such as a fatty, fishy or rancid taste caused by copper ion catalysed oxidation of fats. The oxidation products accumulate in the fat when churning soured cream, whereas they accumulate in the buttermilk when churning sweet cream.

Furthermore, if there are any free fatty acids in the cream (for example, fatty acids formed by the action of lipase), these tend to accumulate in the fat and therefore control the acidity of the resulting butter.

A number of proposals have been made with a view to alleviating the above problems. For example, there are disclosed in Dutch patent applications 71,09891 and 74,05185 methods of preparing butter by churning acidified cream (that is, non-soured or only slightly soured cream to which is added an acid or an acid concentrate obtained from a starter). However, this method involves the production of sour buttermilk and copper ion catalysed oxidation and increased acidity of the fat are unavoidable.

In German Auslegeschrift 1136184, there is disclosed a method of preparing butter by churning sweet cream, separating the resulting butter from the sweet buttermilk and adding to the butter a starter concentrate detained by evaporating, dialysing or freezing a starter. According to a preferred embodiment of this method, milk protein and associated aroma-forming - 4 bacteria are separated from the aqueous phase of the starter (which still contains lactic bacteria) and at least the aqueous phase is fractionally condensed, the fractional condensate then being combined with the milk protein to form the starter concentrate which is added to the butter. According to this method, the resulting butter is said to have a pleasant fresh sour aromatic flavour, similar to that obtained by churning microbially soured cream.

The method disclosed in the above German Auslegeschrift involves either evaporation, dialysis or freezing, each of which is disadvantageous, for the following reasons:(a) evaporation involves removal of aromatic substances together with water vapour, and flocculated protein tends to be deposited on the walls of the evaporator; (b) dialysis involves loss of materials which pass through a dialysis membrane, such as lactose, lactic acid and some of the aromatic substances, in addition to water; and (c) freezing involves the production of a mixture of ice crystals, proteins and bacteria which is impossible to separate into protein-free,, ice-free and bacteria-free compositions.

We have now developed a method of preparing aromatic soured butter in which non-soured cream is churned (whereby sweet buttermilk is formed as a byproduct and not the less preferred sour buttermilk) in which the above disadvantages are at least partially alleviated.

According to the invention, there is provideda method of preparing aromatic soured butter which comprises the steps of: (a) churning a non-soured cream having a fat con5 tent of 15 to 75% by weight at 5 to 20°C so as to obtain butter and sweet buttermilk; (b) draining off the sweet buttermilk; and (c) kneading into the butter at least one aromatic starter and up to 2%, based on the weight of the butter, of a non-aromatic. Qoncentrate so. as to form ,. _ _ butter, the serum of which has a pH not exceeding 5.5, the starter and the concentrate being separately prepared aqueous solutions made by a method comprising microbial culture of a low fat milk product.

The resulting butter contains only substances which either occur naturally in milk or are formed by microbial action on milk and contains few copper ions and little free fatty acid.

The souring and churning take place separately 20 so that optimum temperatures can be selected for each step to produce good organoleptic and rheological properties. Furthermore, the souring bacteria used in the method according to the invention act on nonfat milk constituents, for example, proteins, to produce aroma substances which are the same as those arising in the souring of cream.

The laws of many countries require that butter contains at least 80% by weight fat and at most 16% by weight water. Since butter containing much less than 14% by weight of water cannot be kneaded satisfactorily, the maximum amount of water introduced in step (c) should be about 2 to 3% by weight. Since it is 439S6 preferable that at least 1% by weight of a good aromatic starter (one having a high diacetyl content) be kneaded into the butter in step (c) in order to achieve good aromatisation of butter, the amount of acid concentrate (which normally contains lactic acid in aqueous solution) is preferably not more than about 1% by weight.

The aromatic starter employed in the method according to the invention is prepared by microbial culture of low fat milk product, such as skimmed milk, sour or sweet whey, or fractions obtained therefrom by physical separation, preferably using microorganisms such as Leuconostic cremoris or, more preferably. Streptococcus diacetilactis, whereby a starter contain15 ing diacetyl and ot -acetyl lactic acid as aroma-forming substances is obtained. The microbial culture may be carried out by a method similar to that described in Dutch patent application 72,05909, which relates to the culture of lactic acid bacteria in whey based liquids to produce lactic starters. The aromatic starter may be a B- starter, a BD- starter or a D- starter, as defined in Ned. Melk en Zuivel Tijdschrift 15 (1961) 225.

The starter preferably contains diacetyl and a25 acetyl lactic acid as indicated above. It is known that α-acetyl lactic acid can be oxidised to diacetyl by agitating a culture containing the former. However, when such an agitated culture is kneaded with butter in step (c) of the method according to the invention, further oxidation to diacetyl has been found to take place, particularly when the moisture distribution in the butter is coarse.

The product of microbial culture may be used as such as the aromatic starter, or protein may be removed and the concentration of aromatic substances increased for use as the aromatic starter.

The separated material may be used as the low fat milk product which is subjected to microbial culture to prepare the nonaromatic acid concentrate for use in the method according to the invention.

Other culture media which may be used for this purpose include skimmed milk and media which act as buffers against lowering of the pH by production of acid, such as sweet or sour whey (obtained as byproducts in the production of cheese, cottage cheese or quark) or whey which contains little lactose. Whey which contains little lactose (which may be a whey mother liquor which has been used for the production of lactose or a solution of whey powder obtained from such a liquor) is advantageous since its ratio of whey protein: lactose is favourable for obtaining a high lactic acid content and a high ratio of lactic acid: unfermented lactose and crystallisation of lactose is unlikely to occur.

When the above media which act as buffers are used, a high lactic acid content can be obtained in the acid concentrate and the pHcan be kept above that at which propagation of lactic acid bacteria stops. Most cultures of lactic acid bacteria propagate at a pH in the range of 4.3 to 4.6. It is preferable, however, to use bacteria which are less sensitive to low pH values, such as Lactobacillus helveticus, which propagates even at pH values less than 3.3. High lactic 43986 - 8 acid concentrations (for example, 20 to 25 grams per litre) can be obtained using this species, particularly when a well-buffered culture medium is used.

A particularly preferred strain of the above species is Lactobacillus helveticus 37 n, which is in the applicant's collection of lactic acid forming bacteria.

An even higher concentration of lactic acid in the resulting solution can be obtained by ultra-filtering whey containing little lactose (as mentioned above) to produce a retentate which is rich in protein and a permeate which is poor in protein, concentrating the permeate by vacuum evaporation or reverse osmosis, optionally evaporating more liquid from the solution and using the resulting concentrate as the culture medium for production of the acid concentrate.

In this manner, the whey proteins lactic acid ratio can be considerably reduced, for example, from 0.20 in Lactobacillus helveticus starter to 0.12 in the ultra20 filtration permeate, and 0.07 in the reverse osmosis permeate, and a lactic acid concentration of more than 35% by weight can be obtained.

The amount of acid concentrate employed in step (c) is preferably not more than 1% by weight so that the pH of the serum is not more than 5.3, more preferably not more than 0.5% by weight so that the pH of the serum is less than 5.0, although a pH of as little as about 4.0 can be obtained using a concentrate in such amounts. When strongly acid and relatively less buffered acid concentrates (as discussed above) are used a serum pH of about 4.0 can be obtained when using 1% by weight of the concentrate and 1% by weight of an aromatic starter in the butter.

In order that the invention may be more fully understood, the following Examples are given by way of illustration only. In each of Examples I to II, the butter used was obtained conventionally by churning nonsoured cream having a fat content of 15 to 75% by weight and draining off the sweet buttermilk.

Example I A B- starter (known in the applicant's laboratory as Fr.B) was inoculated into 500 kg skimmed milk, after which cottage cheese was prepared in the known way, from which, using a centrifugal decanter, 290 kg clear sour quark whey of pH 4.8 was separated. In this whey, 2% by volume of a culture in skimmed milk of Lactobacillus helveticus, strain 37n (a micro-organism from the applicant's collection of lactic acid forming bacteria as mentioned above) was incubated and after 72 hours at 37°C the culture had a pH of 3.3.

The resulting soured whey, cooled to 4°C, was separated by ultra-filtration to form 25 kg of retentate and 265 kg of permeate which had a protein content of 0.28 weight % and a lactic acid content of 22.2 grams per litre. The permeate was separated by reverse osmosis to form 31 kg of retentate rich in protein and 234 kg of permeate with a protein content of 0.08 weight % and a lactic acid-content of 12.2 g/1. This last permeate was concentrated at 42°C using a circulation evaporator until 6.5 kg of a clear liquid concentrate with a pH of 2.8, a protein content of 2.3 weight % of a lactic acid content of 362 g/1 remained. 43S®6 To butter obtained by churning nonsoured cream was added 1% by weight of a matured strongly aromatic D-starter (known in the applicant's collection as 4/25), together with 1% by weight of the concentrated permeate.

After dry kneading the butter, the pH of the serum was 5.0. With 0.5% by weight of the concentrated permeate the pH of the serum was 5.3.

Example XI Using a BD- starter, known as Ur from the applicant's collection. Gouda cheese was prepared in the usual way. The cheese whey thus Obtained of pH 6.5 was further soured at 37°C with L. helveticus as in example I until the pH reached 3.6, then cooled and ultrafiltered. The resulting permeate which contained 0.23% by weight protein and 19.3 k/1 lactic acid, was concentrated in a circulation evaporator to form a clear concentrate with a pH of 162 g/1 and a protein content of 2.0% by weight.

Butter obtained by churning non-soured cream was then kneaded with 1% by weight of matured BDstarter Ur (as mentioned above) and, in three batches, 2%, 1% or 0.5% by weight, respectively, of the concentrate prepared as described above.

The resulting batches of butter had sera of pH 4.4, 4.9 and 5.2, respectively.

Example III Pasteurised cream having a fat content of 39.2 weight % was kept overnight at 6°C and then heated to 13°C in order to obtain the required level of crystall30 isation of the fat. Using a Westfalia continuous butter machine, the cream was then churned to produce - 11 butter at an output rate of 480 kg/h, while separating the non-soured buttermilk produced. 10 litres per hour of the aromatic D-starter used in Example I (which had been pre-aerated) and 1200 ml. per hour (i.e. about 0.25% by weight) of the clear liquid concentrate prepared as in Example I were added to the butter, which was then dry-kneaded. The butter obtained was kept for a fortnight at 14°C and afterwards subjected to an organoleptic quality evaluation by the Nederlands Zuivel Kwaliteitscontrole Bureau (ZKB; Dutch Dairyproducts Quality Control Office), as usual for butter which is prepared from soured cream. The butter had a ZKB grade of 1. Its moisture content 1.51% by weight the pH of the serum was 5.1 and the diacetyl content 4.2 mg/kg. After three month's storage at -12°C the butter was again inspected and had a ZKB grade of I-, which for cold store butter is a good result.

Example IV From a diary plant where quark is made using the B-starter referred to above as Fr.8, whey was obtained which was pasteurised for 10 seconds at 74°C. The acidity of 63°N (as determined according to NEN Standard 913). To 8678 litre of this sour whey, 1041 litres of a culture of L. helveticus strain 37n in skimmed milk was added and incubated for 4 days in a tank for souring cream, when the acidity was 235°N and the pH 3.3. Then the whey was cooled to 4 °C and stored.

By ultraviltration at 25°C, 8455 litres permeate with a solids content of 4.44 weight % and an acidity of 23O°N were obtained from this whey. This permeate was concentrated in a triple effect falling film 43θ86 - 12 evaporator to produce a concentrate of solids content 21.9 weight % and an acidity of 1050°N. 4900 litres pasteurised sweet cream having a fat content of 34.6 weight % were kept overnight at 8°C, then heated to 13°C and transferred into a rollerless stainless steel churn in which the cream was churned and the non-soured buttermilk drained off and squeezed out. .5 litres of the concentrated permeate prepared, as described above (about 0.75% by weight) was added to the resulting butter, followed by 60 litres of matured aromatic B- starter Fr.19 and the butter was then kneaded and stored for a fortnight at 14°C.

The moisture content of the butter was then 16.0 % by weight, the non-fat solids content thereof was 1.46% by weight, the diacetyl content thereof was 3.0 p.p.m. and the pH of the serum was 4.75. The butter has a ZKB grade of I.

Example V 7540 kg cream having a fat content of 38.0 weight % were pasteurised, cooled to 6°C and stored for one night. After heating to 10°C, churning and kneading were carried out in a continuous butter-making machine by the method of example III, except that the output of butter was 1200 kg per hour. .56 kg. of the concentrated permeate produced as in Example IV and 12.50 kg of aerated mature Dstarter 4/25 (as referred to above) were kneaded into the butter per hour, as in Example III. The butter thus contained 0.88% by weight of the concentrated permeate and 1.04% by weight of the D-starter. - 13 The butter was then stored for 14 days at 14°C, whereupon its moisture content was 15.3% by weight, its non-fat solids content was 1.65% by weight, its diacetyl content was 3.0 p.p.m. and the pH of the serum was 5.15. The butter had a ZKB grade of I.

Example VI A quantity of pasteurised cream was divided in two portions A and B. Cream A was soured conventionally churned and kneaded into butter. Cream B was churned in the sweet state and before dry kneading, an aromatic starter and a concentrate prepared according to Example IV were added to the butter. The copper content was determined in both batches of butter. The butter was stored for three months at -12°C and then organoleptically examined by a number of qualified food inspectors from the applicant's laboratory. Each sample was rated for flavour within the range of 3 (very bad) to 8 (very good), for oxidation taste in the range 0 (no oxidation taste). Each rating was carried out four times and the average results obtained. None of the samples was rancid (that is nona contained non-esterified fatty acids in detectable quantities). The copper content of each butter was evaluated and butters of group B, prepared according to the invention, have considerable lower copper content than butters of group A, churned in a soured condition not according to the invention.

The fact that the oxidation taste hardly occurs in butters of group B after three months' cold storage as well as the higher estimation of flavour and taste, can be attributed to this.

The results of the above tests are shown in Table A, following Example VII.

Example VII An aqueous solution of 2.5% by weight of powdered whey containing 4.1% by weight lactose and 28% by weight protein, was pasteurised for 15 seconds at 73°C. To the solution were added 4.8% by weight of a culture of L. helveticus, strain 37n, followed by incubation at 37°C for 69 hours. The culture then had an acidity of 147°N whilst the lactose content had decreased to 50 mg/kg. The culture was then heated for 15 seconds at 93°C in order to denature the whey proteins, so lowering the buffering powder of the liquid (the liquid being referred to below as liquid A). A portion of Liquid A was then evaporated to 13% of its original volume. The denatured protein was removed by centrifuging from the remainder of Liquid A, which then was evaporated, whereby the volume was reduced to 12%(Liquid B) or to 5% (Liquid C) of the original value.

The butter serum was separated from a small quantity of butter having a moisture content of 74% by weight obtained by churning non-soured cream and then kept in cold storage for three months. Then it was determined in an butter serum test how the pH of this serum decreased by titration with any of the above concentrates.

In this test, a starter was first added (in this case 1.5 g of the D-starter 4/25, which corresponds to 1.5% by weight in the butter) to 14 g of the serum obtained from 100 g of the butter. Since the concentrate C was too viscous to be titrated, this was diluted beforehand to 6% of the original volume. The results are given in the following Table B. 439S6 - 15 From each concentrate a quantity corresponding to that required for achieving a pH of 5.0 in the serum was added and together with 1.5 weight % of the starter 4/25 kneaded into the sweet-cream butter, heated to 13°C. In this way butter was obtained which in a taste test can hardly be distinguished from butter prepared from soured cream. Φ r4 Λ $ L0 Μ' -Ρ S •Η Ε ’Φ ft φ «Φ μ Ό ο 10 ο ο & Η 0 Φ • • ιμ •μ 6 ό ο ο ί>1 β ιμ Λ •μ Ό •μ φ υ Μ Φ μ ft σι Ιθ στ ι—( «ο • •μ • • » • Ο β β Ο ο «μ Ο β 0 φ •μ •μ 0 τί «μ β Ό tf 0 γ4 OJ 10 10 Φ +> • • •μ 10 10 10 10 ιμ tf £ 00 00 <· • • • • ιη m m 10 V Φ Λ υι •μ γ-4 S ω φ tf Φ Μ Ο I •μ φ φ φ •μ tf μ •μ β Φ □ β ο ρ υ μ φ ψι σι ο ω § Μ Ή in Ν <Φ <*) m OJ ΓΏ (μ μ Ο β tt 0 ft β Φ .β μ ιμ 'β ο β tf 3* β Μ •μ φ S & Φ Ο> W β •rt - > β φ - β Ή Ο Μ Λ φ Ο Οι 10 nJ Φ Λ μ <μ ο φ σι μ ο tf ♦μ μ μ μ to β μ φ •Ρ tf £ β Ε ft £ •Ο •μ °Λ2 tf ο ο •μ •μ *ϋ ο ·μ tf υ «μ nj β •μ Φ Λ μ Ο · μ -μ ft £ φ w -μ Ο Λ μ tn u ·μ tf Φ Η £ «μ μ -μ Φ ft φ μ 0 Ό ε Η £ tf β Φ β Η Η > 0 μ 0 IQ co Η Η Η Η Ρ1 ω U Ε m ιη ο ο» Ό ω Ο Ο Ο «μ •φ μ ιη ’Φ οι ό 6 Ο ΟΙ 00 OJ ΓΏ OJ γ4 • Ο ο Ο ΟΙ στ CO ΟΙ »μ Ο * • Ο Ο Ο «μ Η σ» • • • η η ΟΙ ιη ιη Ο ΟΤ ο· ω ο τμ ιη «μ r-t οι ω *Φ Ό m ΓΟ CN r-J Η «μ ι** «μ Ο στ 10 Μ* • « • ιη ιη «μ «μ σ» Οί Ο ΓΠ «φ σι Ο Ο Ο Ο Ο Ο Ε υ - 17 Examples VIII to XXVIII Lactobacillus helveticus strain 37 n was incubated for four days by the method described in Example IV, ultrafiltered and the permeate was evaporated until the solids content dropped to 22, 23 and 32% by weight respectively. The concentrated permeate along with a starter was kneaded into non-soured churned butter as used in Example I using either a churn or a continuous butter making machine - as in Example IV or Example V, respectively. The starter was the aerated D-starter 4/25 or - depending on the degree of moisture distribution aimed at by the plant concerned - the slightly less aroma forming B-starter Fr.19, or even a mixture of both starters in the ratio of 2 to 1 parts by volume.

Table C lists the quantities of starter and concentrated permeate which were kneaded into the butter and the composition of the butter thus produced, after 14 days' storage at 14°C. The stored butter in each case had a ZKB grade of I, except in Example XI which was of grade I—. The butter in Examples VIII to XVI inclusive was, after three months' storage at -12°C in all cases of ZKB grade I. - 18 Table C Experimental production of cultured butter from sweet cream in commercial creameries.

Example Plant 1) Starter Type 2) Permeate used dry matter weight % 2) VIII A K 4/25 2.00 32 0.65 IX A C 4/25 2.15 22 0.65 X A K 4/25 1.50 32 0.60 XI A K 4/25 1.50 32 0.60 XII A c 4/25 1.60 32 0.70 XIII A K 4/25 1.50 22 0.70 XIV A c 4/25 1.50 22 0.73 XV A K 4/25 1.50 22 0.49 XVI A c 4/25 1.80 22 0.74 XVII A c . 4/25 1.50 22 0.60 XVIII B K 4/25 1.50 22 0.70 XIX B K 4/25 1.00 22 0.70 XX B K FR. 19 1.76 22 0.71 XXI C c 4) 0.84 22 0.71 XXII C c 4) 0.82 22 0.66 XXIII C c 4) 0.82 22 0.73 XXIV D 3) 4/25 1.10 22 0.80 XXV E c 4/25 1.00 22 0.80 XXVI E c 4/25 1.07 22 0.80 XXVII F K 4/25 1.00 22 0.70 XXVIII G K FR. 19 2.00 22 0.80 - 19 Butter quantity kg moisture non-fat solids diacetyl serum ZKB weight % weight % ppm pH grade 242 15.7 2.8 4.45 I 120 15.8 1.49 4.3 5.10 I 342 15.9 1.59 - 4.65 I 552 16.0 - - 4.65 I - 200 15.7 1.72 2.4 4.80 I 482 16.0 - 2.3 4.65 I 300 15.3 - 2.8 4.80 I 451 16.0 - - 5.00 I 190 15.8 - 2.9 4.65 I 1286 16.2 1.40 2.7 4.90 I 2214 16.0 1.48 6.1 4.80 I 2199 15.7 1.39 5.8 5.00 I 2095 15.8 1.54 2.1 4.95 I 3328 15.5 1.42 2.2 5.10 I 5722 15.7 1.37 2.3 5.20 I 4440 15.5 1.22 2.4 5.10 I 1850 15.9 1.57 3.9 5.00 I 1931 15.7 1.60 3.7 5.15 I 1265 15.4 1.65 5.2 5.05 I 2212 15.8 1.40 3.0 5.15 I 1958 15.8 1.43 2.0 4.70 I in the above Table C, the following numbers have the meanings given. 1) Type of Churning Equipment: C=continuous butter making machine K=Churn 2) Amount added (by weight based on butter quantity). 3) Churned continuously, then dry kneaded in the churn 439 8 6 - 20 with starter and concentrate 4) Mixture of aromatic starters 4/25 and Fr.19 in a ratio of 2 : 1 parts by volume.

Example XXIX into steamed skimmed milk 0.5% by volume of a culture of L. helveticus was inoculated followed by incubation at 37°C. After 23 hours the acidity had risen to 774°N. 1.5% by weight of the resulting culture was added to sweet-cream butter (as in Example I), the moisture content of which was 13% by weight, together with 1% by weight of a matured aromatic starter - the D-starter 4/25 - and the butter was then dry kneaded. After this the pH of the serum was 5.3.

The L. helveticus culture was incubated still more until after 45 hours the acidity had reached 336°N. To two other portions of the same sweet-cream butter 1% by weight c the D-starter 4/25 and 1..5/by weight of the first mentioned, starter resp. ox 1.0% by weight of the culture were adaea ana kneaded in. After the required distribution of moisture had been reached, the pH of each butter serum was 5.15 and 5.3, respectively.

Examples XXX - XXXII In three tests, butter was prepared by Using a continuous butter making apparatus, as disclosed in Example III, at an output of 630 kg/hour. 1.6% by weight of the aerated starter ”4/25 were incorporated in the butter, which scarcely affected the final pH of the butter serum. Acid concentrates prepared from acid quark whey as disclosed in Example I were added to the 3o butter in the amounts indicated in Table D.

In this table the concentration, acidity and specific gravity of the acid concentrates are shown. - 21 43986 The properties of the resulting butter are also shown in Table D.

Table D Example Data of acid concen- trate Proportion of acid concentrate kneaded Butter ZKB grade after butter % by Serum Humdity diacetyl pH weight ppm % 14 days at 14° XXX 33% by weight solids 0.23 5.45 15.3 2.3 I” s.g. 1.151 0.40 5.10 15.7 3.5 I 146O°N 0.64 4.65 15.7 2.4 I XXXI idem 0.36 5.35 15.8 2.3 I 0.56 4.85 15.5 2.1 I XXXIX 28% by weight solids 0.45 5.10 16.3 3.1 I - s.g. 0.74 4.75 16.0 2.5 I 1.128 1200°N Examples XXXIII - XLVII Whey powder, poor in lactose, was dissolved in water at a solids concentration of 3.6% by weight.

After conventional pasteurization, 3% by weight of a Lactobacillus helveticus strain 37n culture were inoculated therein. After 2 days incubation at 37°C the pH of the culture was 3.20. The culture was ultra-filtered so as to reduce its volume by 92%. The permeate obtained was evaporated till the solids content was 24% by weight. The acidity of the concentrate was 1800°N.

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Claims (15)

1. A method of preparing aromatic soured butter, which comprises the steps of: (a) churning a non-soured cream having a fat

2. %, based on the weight of the butter,

3. A method according to claim 2, in which the 20 amount of non-aromatic acid concentrate employed in step (c) is up to 0.5%, based on the weight of the butter, and the pH of the serum is not more than 5.0.

4. A method according to any of olaims 1 to 3, in which the non-aromatic acid concentrate is obtained 25 by culturing bacteria of the species Lactobacillus Helveticus on a low fat milk product.

5. A method according to claim 4, in which the bacteria are of the strain Lactobacillus Helveticus 37 n. 5 content of 15 to 75% by weight at 5 to 20°C so as to obtain butter and sweet buttermilk; (b) draining off the sweet buttermilk; and (c) kneading into the butter at least one aromatic starter and up to

6. A method according to any of claims 1 to 5, 30 in which the or each microbial culture of a low fat milk product is carried out for up to 96 hours at approximately 37°C.

7. A method according to any of claims 1 to 6, in which the low fat milk product used in the preparation of the non-aromatic acid concentrate is sweet or sour whey or a solution obtained therefrom.

8. A method according to claim 7, in which the whey is acid quark whey.

9. A method according to claim 7 or 8, in which the whey contains little lactose. lo. A method according to any of claims 7 to 9, in which the solution is obtained from the whey by a method comprising ultrafiltration and concentration of the resulting permeate.

10. Of a non-aromatic acid concentrate so as to form butter the serum of which has a pH not exceeding 5.5, the starter and the concentrate being separately prepared aqueous solutions made by a method comprising microbial culture of a low fat milk product. 15 2. A method according to claim 1, in which the amount of non-aromatic acid concentrate employed in step (c) is up to 1%, based on the weight of the butter, and the pH of the serum is not more than 5.3.

11. A method according to any of claims 1 to 10, in which the microbial culture to produce the acid concentrate is carried cut in the presence of buffers naturally present in the low fat milk product, the buffers being removed before kneading the concentrate into the butter.

12. A method according to any of claims 1 to 11, in which the aromatic starter is prepared by microbial culture under such conditions that diacetyl and a-acetyl lactic acid is formed.

13. A method according to claim 12, in which the aromatic starter is prepared by culturing bacteria of the species Streptococcus diacetilactus.

14. as herein A method according to claim 1, substantially described in any of Examples I to XLVII.

15. according Aromatic to any of soured butter prepared by a method the preceding claims.