Possible Uses of Lactic acid Bacteria for Food and Feed Production

Lactic acid bacteria (LAB) are generally fastidious on artificiall media, but they grow readily in most food substrates and lower the pH rapidly to a point where competing organisms are no longer able to grow. Spontaneous fermentation of food/feed may differ from each other in terms of environmental microbiota and fermentable substrate. Spontaneous fermentation may fail, because it is not possible to ensure the same quality of the end product. However, spontaneously fermented products represent a source of LAB with potential interesting functional and technological properties, and the choice of the starter cultures has a critical impact on the palatability, processability, nutritional attributes, sustainability, and safety of food and feed.


Introduction
Lactic acid bacteria (LAB) are generally fastidious on artificiall media, but they grow readily in most food substrates and lower the pH rapidly to a point where competing organisms are no longer able to grow. Spontaneous fermentation of food/feed may differ from each other in terms of environmental microbiota and fermentable substrate. Spontaneous fermentation may fail, because it is not possible to ensure the same quality of the end product. However, spontaneously fermented products represent a source of LAB with potential interesting functional and technological properties, and the choice of the starter cultures has a critical impact on the palatability, processability, nutritional attributes, sustainability, and safety of food and feed.

Lactic acid bacteria for bread production
Sourdough fermentation is the most natural and bestperforming process to ensure optimal sensory and functional characteristics of bread, also, it should be noted, that the selection of LAB, having peculiar characteristics, can reduce the mould growth [1] and acrylamide formation in bread [2][3][4][5]. The acrylamide content in mixed rye -wheat bread could be lowered by using LAB with lower amylolytic activity [3]. Thus, the significant effect of LAB protease activity on the fermentation process as well as on acrylamide formation in bread can be related. A. niger glucoamylase in conjunction with an appropriate LAB strain could be used as one of the factors regulating acidification in dough, herewith decreasing the acrylamide content in bread. Also, a number of fermented products utilize cereals in combination with legumes, thus improving the overall protein quality of the fermented product. Cereals are deficient in lysine, but are rich in cystine and methionine, legumes on the other hand are rich in lysine but deficient in sulphur-containing amino acids [6-8]. Hereby, by combining cereals with legumes, the overall protein quality of bread could be improved. Fermentation of lupine by pure LAB significantly improved the nutritive value of lupine eliminating the trypsin inhibitors (reduction of 21.8%) and increasing the soluble protein content up to 18.9% thus improving protein digestibility by 17.1% [5].

Lactic acid bacteria for tomatoes nutritional value increasing
Processing of tomatoes with selected LAB strains resulted in several important changes in carotenoid concentration and lycopene isomer profile. Treatment with LAB breaks down the tomato cell matrix and makes the carotenoids more available, which resulted in higher level of total carotenoids. Moreover, lactic acid fermentation of tomato resulted in a large lycopene bioavailability accompanied by increased cis-lycopene content. According to our results, selected LABmay be useful for preservation of tomatoes, which could be recommended as a way of obtaining more biologically accessible products with functional value [9].

Lactic acid bacteria for meat products value and safety increasing
The nutritional strategies to improve the quality of food products of animal origin are relatively newapproach. Acoording to our results, fermented with selected LAB tomato powder can be recommended as both a colouring agent and a source of lycopenein the preparation of ready-to-cook minced pork meat [10]. Satureja montana L. plants fermented with BLIS producing LAB could be a good alternative for ready-to-cook minced porkprocessing to prevent meat decolouration and microbial spoilage, thus increasing acceptability and shelf-life of meat products [11]. Also, our study showed the potential to use the potato tuber juice as a natural substrate for LAB fermentation and natural marinades for meat treatment production. The cheap natural marinades,based on potato juice fermented with selected LAB,could be recommended for pork meat treatment to improve its tenderness and color, thus increasing the overall acceptability [12]. Furthermore, the influence of surface treatment selected LAB, previously cultivated in an potato juice, on the formation of polycyclic aromatic hydrocarbons (PAHs) and biogenic amines (BAs) incold smoked pork meat sausages was investigated. Moreover, sausages treatment with LAB after the smoking on PAHs content changes was evaluated. Additionally, the inhibitory effects of LAB metabolites on food spoilage bacteria was determined [13]. The results confirm that potato juice could be used as an alternative substrate for LAB cultivation, and the obtained fermented bioproducts could be applied for surface treatment of cold smoked pork sausages in case to reduce microbial contamination, and PAHs content in final product.

Lactic acid bacteria for higher value feed production
The 50ml of with selected LAB fermented potato juice contain¬ing 9.6 log10 CFU/ml of LAB per day, administered for 14days, reduced the risk of developing acidosis (it stabilised blood pH; P<0.05), reduced lactate and PCO2 concentrations (P<0.05), and the risk of liver lesions (reduced AST concentration; P<0.005) in blood and E. coli in the faeces of calves [14].
As well as the isolated Pediococcus acidilactici BaltBio01 and Pediococcus pentosaceus BaltBio02 strains were cultivated in barley and wheat bran (90/10, m/m) substrate, and the developed fermented feed stock, with high content of valuable Pediococcus, was used for Lithuanian black and white dairy cattle feeding [15]. In addition, the influence of fermented feed stock on milk production and composition was determined. Isolated strains demonstrated versatile carbohydrate metabolism, grown at 30 °C and 37 °C temperatures, acidic tolerance, showed to be non resistant to antibiotics and have antimicrobial activity. Cereal by-products (barley and wheat bran) bioconversion using isolated microorganisms allows to produce safer (reduced Enterobacteria, aerobic bacteria, yeast and fungi count) fermented feed stock with high content of Pediococcus. At the beginning of the feeding experiment, no significant differences in feed intake, milk production and milk composition were established between the test groups. Control and trial groups received the same ration; however, the trial groups also received 200g per cow of the fermented feed stock containing 9.6 log10 CFU g-1 Pediococcus daily for 66 days (group B, received 200g fermented with P. acidilactici/cow/day feed stock, group C received 200g fermented with P. pentosaceus/cow/day feed stock, and group D received 200g fermented with P. acidilactici and P. pentosaceus/cow/day feed stock). After 33 days of experiment, significant milk yield increase in group D (yield 34.64±3.56kg d-1), compared with group A (yield 29.93±3.55kg d-1) and group C (yield 30.24±3.99kg d-1) was established. After 66 days of feeding, similar trends were found, i.e. milk yield significantly increased in group D (yield 35.04±3.04kg d-1) compared with group A (yield 29.04± 3.88kg d-1).
It can be inferred that barley and wheat bran could be used to promote growth of P. acidilactici BaltBio01 and P. pentosaceus BaltBio02, and produced fermented feed stock could be recommended for dairy cattle feeding in order to increase milk production [16][17][18].

Conclusion
The value of fermented food/feed play a vital role in diet and nutrition. The benefits which are associated with fermentation are increased shelf life and sustainability, palatability, and nutritional value. Application of lactic acid bacteria for the food/ feed biotechnology industry look promising and warrant further research.