IJFS#1438_bozza Ital. J. Food Sci., vol. 31, 2019 - 437 PAPER EFFECTS OF PROBIOTIC FERMENTATION OF SELECTED MILK AND WHEY PROTEIN PREPARATIONS ON BIOACTIVE AND TECHNOLOGICAL PROPERTIES K. SKRZYPCZAK1*, E. FORNAL2, A. WAŚKO3 and W. GUSTAW1 1Department of Plant Food Technology and Gastronomy, Department of Fruits, Vegetables and Mushrooms Technology, Faculty of Food Science and Biotechnology, University of Life Sciences in Lublin, Skromna 8, 20-704 Lublin, Poland 2Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8b, 20-090 Lublin, Poland 3Department of Biotechnology, Microbiology and Human Nutrition, Faculty of Food Science and Biotechnology, University of Life Sciences in Lublin, Skromna 8, 20-704 Lublin, Poland *Corresponding author: katarzyna.skrzypczak@up.lublin.pl ABSTRACT The objective of this study was to compare the effect of probiotic fermentation (conducted by L. acidophilus LA-5) of milk containing an addition of selected whey or milk protein preparations (whey protein concentrates, whole milk, whey protein isolate, casein glycomacropeptide or α-lactalbumin) on the technological and functional properties of obtained milk beverages. Determination of the antioxidative activities and identification sequences of biologically active peptides generated in selected protein preparations during probiotic fermentation also constituted the aim of the research. The results obtained indicate that the addition (1%) of α-lactalbumin into regenerated skimmed milk in the highest degree reduced the syneresis level in fermented products. Also, α- lactalbumin hydrolysates exhibited the strongest antioxidative properties (57.57±6.6%), while casein glycomacropeptide hydrolysates allowed us to obtain the highest amount of various biopeptides. Keywords: biopeptides, lactic acid fermentation, probiotics Ital. J. Food Sci., vol. 31, 2019 - 438 1. INTRODUCTION The area of functional food that becomes a part of an everyday diet (NAGPAL et al., 2012) and the significance of many dairy products, especially fermented ones, is dynamically developing. Nowadays, it is observed that the consumers’ awareness of the role of diet and beneficial health effects of some food compounds is on the increase, a fact also reflected in higher consumption of fermented milk products. Simultaneously, the requirements of and demand for various the health-promoting features of those kinds of products have been growing too. Therefore, to meet those expectations, scientists and the dairy industry are aiming at improving the technological and functional properties of dairy products as well as creating new ones. Proteins are the most valuable constituent of whey protein isolates (WPI) and whey protein concentrates (WPC) that supply good nutritional quality and enhance the functionality of many product formulations (GUSTAW and MLEKO, 2007; JEEWANTHI et al., 2015). It is suggested that selected whey protein constituents (e.g.α-lactalbumin, lactoferrin, serum albumin lactoperoxidase, β-lactoglobulin, bovine) and peptides deriving from them exhibit, among others, an anticarcinogenic activity, may stimulate the immune system and influence metabolic processes (GOBBETTI et al., 2002). Therefore, they constitute an important source of bioactive ingredients that might find an application, e.g. in the preparation of some of the functional food and therapeutic formulations (KABAŠINSKIENĖ et al., 2015). Furthermore, apart from nutritional aspects, whey (as well as products deriving from it) is also a functional component that might influence some products’ properties, including colour, flavour, and texture (LIUTKEVIČIUS et al., 2016). Thus, incorporation of selected milk and whey protein preparation might not only enhance the technological properties of a product but might also positively influence the functional properties. This is largely associated with the fact that milk and whey proteins are precursors of biologically active peptide sequences (biopeptides), which exhibit a wide range of desired beneficial health effects affecting the regulation of the human body’s system functions (MOHANTY et al., 2016; LUCARINI, 2017). However, biopeptides enclosed within a native structure of milk and whey proteins are inactive, whereas enzymatic hydrolysis with digestive enzymes as well as fermentation process conducted by a starter culture with an efficient proteolytic enzyme system contributes to the release of various sequences of active peptides (KORHONEN and PIHLANTO, 2003; MICHAELIDOU, 2008). Moreover, bacteria involved in the fermentation processes not only contribute to the formation of bioactive substances that give food product a functional characteristic, but determined strains meeting certain requirements may also constitute a functional food component. The microorganisms claimed as probiotics constitute another important functional food constituent that might be introduced to milk products. An activity of probiotics contributes to the modification of the microbiota composition in the host’s intestines, which influences some of the physiological process leading to favourable health consequences. The health-promoting effects caused by probiotics concern their desired influence on maintaining proper intestine micrflora (normalization of the bacteria composition, e.g. after antybioticoteraphy), hypocholesterolemic or anticarcinogenesis effects, inhibition growth of some pathogens, stimulating the immunity system and also alleviation of some of the allergy, including food allergies and lactose intolerance (SARKAR et al., 2016). The objective of this study was to compare the effect of probiotic fermentation (conducted by L. acidophilus LA-5) of milk containing the addition of chosen whey and milk protein preparations on technological and functional properties of obtained milk beverages. The study was also focused on evaluation of the antioxidative activities and determination of Ital. J. Food Sci., vol. 31, 2019 - 439 the biologically active peptide sequences generated during probiotic fermentation of selected protein preparations. 2. MATERIAL AND METHODS 2.1. Microorganism and growth conditions The probiotics strain Lactobacillus acidophilus LA-5 (Chr. Hansen, Poland) was stored at -80°C in Man- Rogosa- Sharpe broth (BTL, Łódź, Poland) containing 15% (v/v) glycerol stock. For further analysis, the strain culture was activated and routinely cultured (2%v/v of inoculum) in MRS broth and incubated at 37°C for 18h under aerobic conditions. 2.2. Fermentation of milk with the addition of protein preparations The samples of 13% regenerated skim milk (OSM Krasnystaw, Poland) were enriched by the 1% (w/v) addition of one of the following protein preparations: whole milk powder (OSM Krasnystaw, Poland) - WMP; whey protein concentrates (Polsero, Poland) - WPC 30 and WPC40; whey protein isolate (Milei GmbH, Allgau, Germany) - WPI; Casein glycomacropeptide (Arla Food, Denmark) - CGMP and α-lactalbumin (Arla Food, Denmark) - α-la. Samples of milk without any protein addition (RSM) were used as a control variant. All obtained sample variants were pasteurized (80°C/30min), then cooled down to ambient temperature and inoculated by 1% (v/v) of Lactobacillus acidophilus LA-5 cell suspension, which was previously prepared as follows: an overnight culture of analyzed probiotic strain (grown in MRS broth) was used to inoculate fresh medium (sterile MRS broth) to obtain an optical density at 600 nm (OD600) of 0.05 (Helios Gamma; Thermo Fisher Scientific), subsequently the bacteria strain was cultivated at 37 °C until an OD600 of 0.7 (exponential phase). Afterwards, bacteria cells were harvested by centrifugation at 8000g for 10 min at 4 °C (MPW 350-R; MPW). The pellet was washed twice with sterile phosphate-buffered saline (PBS, pH 7.0) and resuspended (also in PBS) to obtain cell suspension of OD600 equal to 0.3 that was used for inoculation. Then, inoculated samples of all milk variants were transferred in equal volumes (40mL) into sterile packages and sealed. After the process of fermentation (42°C/12h, thermostatic method), all samples were cooled down up to 4°C and maintained in this temperature for another 12h before further analysis. 2.3. Texture profile analysis To compare the textural properties of the fermented products received, the texture profile analysis (TPA) was performed, using a TA-XT2i (Stable Micro Systems, Godalming, UK), according to the procedure described by GUSTAW et al. (2016). The parameters hardness, fracturability springiness, cohesiveness, gumminess and chewiness were included in the analyses. 2.4. Spontaneous syneresis assay The acidic milk gels (the fermented final products) obtained were analyzed also in terms of their ability for water binding. Therefore, the level of syneresis in received products was measured according to the method described by AMATAYAKUL et al. (2006). Ital. J. Food Sci., vol. 31, 2019 - 440 2.5. Hydrolysis of milk and whey protein preparations Aqueous solutions (1% w/v) of skim milk powder (SMP) and all above-mentioned protein preparations were pasteurized in a water bath (80 ˚C/30 min). After cooling down up to 35 °C, all variants of solutions were inoculated (1% v/v) by previously prepared inoculum (uninoculated samples were control variants) and incubated at 37 °C for 24 h. Subsequently, all samples were heated at 100 °C for 5 min in water bath to inhibit the hydrolysis process and inactivation of bacterial enzymes. Then, all samples were filtered (syringe filter Ø = 0.45 μm) and subjected to further analysis. 2.6. Antioxidant activity An antioxidant activity in obtained filtrates (of fermented and nonfermented 1% (w/v) aqueous solutions of skim milk powder [SMP] and all analyzed protein preparations) were determined as an ability for free radical scavenging, using alcoholic solution of DPPH (1,1-Diphenyl-2-picrylhydrazyl, Sigma-Aldrich, Poland) in accordance with the method described by NAMDARI and NEJATI (2016). Briefly, the analyzed samples were diluted with phosphate buffer (0.1 M) in ratio 1:4. Afterwards, to 1 ml of each of the diluted samples 2.5 ml of 0.1 mM DPPH (in 60% methanol) was added and vigorously mixed. After 30 min of sample incubation (in darkness at ambient temperature), the absorbance was measured at λ=517 nm. The determination of the value of the analyzed activity for tested samples was carried out in a five-fold repetition (n=5). Antioxidant activity (radical-scavenging activity) was expressed as % inhibition of DPPH-absorbance that was calculated using the equation: Inhibition [%] = [(Ac-As)/Ac] x100 where, As - absorbance (λ=517 nm) of the test sample, and Ac - the absorbance (λ=517 nm) of the control sample consisting of 1 ml phosphate buffer mixed with 2.5 ml of DPPH (the methanolic solution of free radicals). 2.7. Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and peptide sequencing To analyze the biopeptides content, those protein preparations characterized by the highest antioxidative activities and the ones that allowed obtaining the fermented products with the most desirable textural properties were selected. The analysis was conducted through the previously described procedure (SKRZYPCZAK et al., 2017) using Agilent Mass Hunter acquisition B.05.01 software to acquire data. The data analysis and peptide mapping were performed using the Agilent Mass Hunter qualitative analysis B.07 with integrated Bioconfirm add-on software. 2.8. Determination of the biological activities of peptide sequences To determine the profiles of potential biological activities, the obtained peptide sequences were subjected to further analysis that was performed according to the procedure included in the databases BIOPEP-UWMP (MINKIEWICZ et al., 2008; DZIUBA et al., 2009; www.uwm.edu.pl/biochemia/index.php/pl/biopep) and BioPepDB (bis.zju.edu.cn/ biopepdbr). Ital. J. Food Sci., vol. 31, 2019 - 441 2.9. Statistical analysis Statistical analysis was performed using the Statistica 8.0 (StatSoft, Poland) program. To evaluate the differences between means values, the data were subjected to analysis of variance (ANOVA) using Tukey’s test with a level of significance set at p<0.05. The similarities of the textural properties analyzed between obtained fermented final products were determined on the basis of the results of bottom-up hierarchical cluster analysis using average linkage clustering as a linkage criterion (UPGMA). To avoid the effect of the differences in measurement units between the parameters on the values of Euclidean distances, the data were standardized prior to the analysis. 3. RESULTS AND DISCUSSION 3.1. Effect of addition of selected protein preparation on the textural properties and syneresis level of fermented products The fermented milk products obtained with the addition of analyzed protein preparations exhibited some variety in terms of texture properties as well as level of spontaneous syneresis (Table 1). Analyzing hardness parameter, there were no statistically significant differences (p<0.05) between control variant and products containing the addition of WPC30, WMP or α-la additions. The highest values of measured parameter were exhibited by samples with addition of CGMP, but simultaneously these fermented products were characterized by the most intensified syneresis effect (Table 1). This might be caused by the formation of a strong bond between generated products of hydrolyzed CGMP that influenced the moulding a strong structural network increasing the strength (hardness) of the gels and enhancing water disposal from the structure of curds. Regarding the values of fracturability as well as cohesiveness (Table 1), there were no differences (p<0.05) between analyzed products. However, comparative analysis of all textural parameters indicated that, in terms of similar of texture profiles, the obtained variants of fermented products might be divided into three clusters consisting of pairs of fermented products’ variants containing one of the tested protein preparations’ addition (WMP with α-la, control variant and WPC30, WPI and CGMP) (Fig. 1). Moreover, the results of cluster analysis indicated that in terms of values of analyzed texture profile parameters (springiness hardness, fracturability, cohesiveness, gumminess and chewiness), fermented beverages containing a WPI or CGMP additive were distinguished from all tested products and constituted a separate and farthest cluster that represents textural properties (Fig. 1). The addition of whey protein concentrate (WPC 30 and WPC40) or CGMP to milk increased the intensity of syneresis in fermented products, while acidic milky gels containing the α-la or WMP addition were characterized by the highest water-binding capacity exhibiting the lowest syneresis effect (Table 1). The obtained results are in accordance with JOVANOVIĆ et al. (2005), who suggested that α-la influence the increase in the hydrophilic properties of the coaggregates at pH 4.5. Moreover, the study of MATUMOTO-PINTRO et al. (2011) indicates that a higher proportion of α -la in the yoghurt ingredients or partial hydrolysis of whey protein polymers inhibit the rate of sedimentation in the fermented product. Ital. J. Food Sci., vol. 31, 2019 - 442 Figure 1. The result of UPGMA analyses. Diagram expresses the similarity of texture characteristics between fermented products regarding all parameters measured in texture profile analysis; the similarity between particular groups of products was expressed as distance [%]; RSM is the control sample (fermented regenerated skim milk [13 %] without addition of any protein preparation). It was claimed that the gelation properties of whey proteins are dependent on hydrolysis conditions and the degree of conducted enzymatic process (JEEWANTHI et al., 2015). The process of gel formation is an effect accompanying the fermentation conducted by starter cultures. Therefore, the modification conditions of the hydrolysis process enable the creation of gels with various rheological properties (CREUSOT and GRUPPEN 2007; POULIOT et al., 2009; JEEWANTHI et al., 2015). Moreover, the results obtained might suggest that preferences of the probiotic strain to composition of fermenting medium (RSM samples containing selected protein preparations) and the specificity of bacterial enzymes toward selected milk and whey proteins might also influence the degree of hydrolysis and various characteristics of received gels (fermented products). It was implied that some of the generated peptide sequences might also initiate the aggregation process of whey protein hydrolyzates that influence the textural and rheological characteristic of fermented milk products. In WPI hydrolysates obtained using bacterial enzymes, CREUSOT and GRUPPEN (2007) identified such peptides and determined their sequences: β-Lg [f1-45], β-Lg AB[f(90-108)]-S-S-α-La [f(50-113)], α-La[f(12-49)]-S-S-α-La [f(50-113)], β-Lg AB[f(90-108)]-S-S-α-Lg AB[f(90-108)], β-Lg A[f(90-157)] and β-Lg AB[f(135-157/158)]. It was reported that in the production of yoghurt, the addition of WPI to milk enhances the formation of disulfide bonds during fermentation, which influences the increase in the mechanical resistance of received acidic gel (MATUMOTO-PINTRO et al., 2011). However, in the presented study the results indicate that the 1% addition of WPI (compared with the control sample) has no significant effect on the improvement of textural property in terms of gel hardness. Study results presented by DĄBROWSKA et al. (2017) revealed that the addition of whey protein hydrolysates (instead of other protein preparations like SMP or WPC80) to milk in yoghurt production might contribute to the increase in counts of starter culture bacteria at the initial stage of fermentation. Moreover, the addition of some whey protein Ital. J. Food Sci., vol. 31, 2019 - 443 hydrolysates into milk improves the viability of probiotic bacteria in the final products (ZHAO et al., 2006; DĄBROWSKA et al., 2017). Also, the prebiotic-like properties of some whey proteins (including WPC) have been confirmed (GUSTAW et al., 2016). This positive effect of selected milk and whey protein preparations, as well as their hydrolysates on the growth of the desired strains of probiotic bacteria, may strengthen the potential of the health-promoting properties of various fermented products. 3.2. Comparing the antioxidant activity of milk and whey protein preparations’ hydrolyzates The fermentation process conducted using the probiotic strain (L. acidophilus LA-5) influenced the increase in the ability of analyzed protein preparation solutions to free radical scavenging (Fig. 2). Unfermented samples of SMP, WMP, WPC 30 and WPC40 exhibited a similar level of DPPH radical scavenging activity (differences, not statistically significant, p> 0.05). Moreover, it was noted that the hydrolysis process carried by tested bacteria improved the antioxidative properties of all analyzed protein preparations (Fig. 2). Figure 2. Antioxidant activity of analyzed protein preparations in DPPH assay. Differences between mean values (x; n=5) of antioxidant activity in obtained filtrates of tested samples (fermented and unfermented aqueous solutions (1% w/v) of skim milk powder [SMP] as control variant of samples and all analyzed protein preparations) denoted by different letters are statistically significant (p<0.05); error bars express the standard deviation (± SD). The samples of α-la and CGMP fermented by probiotic strain exhibited the strongest hydrogen-donating capacity among analyzed solutions of protein preparations (57.57±6.6% and 54.87±1.3%, respectively). Differences in the value of antioxidative activity recorded for both types of samples were not statistically significant (p> 0.05), while the lowest values were noted for samples of SMP before (24.90±0.81%) as well as after hydrolysis (29.53±3.0%). These results are in accordance with RAHMAWATI and SUNTORNSUK (2016), who suggested that increased antioxidant activities in yoghurt (compared to raw milk material) might be associated with the released peptides (antioxidative) by bacterial proteolitic enzymes from protein molecules during the fermentation process. The peptides generated through protein hydrolysis as well as some products of the bacteria metabolism exhibit properties of electron donors and react with free radicals (DPPH) to achieve more stable molecule (KULLISAAR et al., 2002). 0 20 40 60 80 SMP WMP α-la WPC40 WPC30 CGMP WPI In hb it io n [% ] Type of analyzed protein preparation fermented unfermented Ital. J. Food Sci., vol. 31, 2019 - 444 3.3. Biological activities of peptide sequences identified in hydrolyzes of selected protein preparations The analysis of identified biopeptides indicates that diversity of amino acid sequences as well as the quantity of the peptides in tested hydrolyzates depended on the protein matrix, namely the type of protein preparation (Table 2). The results of liquid chromatography-high-resolution mass spectrometry (LC-HRMS)-and peptide sequencing revealed that most of the identified biopeptides sequences in analyzed hydrolyzates of protein preparations possess potential antihypertensive activities (Table 2) while in only one hydrolyzate (WPI) the presence of the sequence (RELEELNVPGEIVESLSSSEESITR) with potential of mineral-binding was confirmed. Furthermore, some of the biopeptide sequences possess more than one biologically active function, for instance, TTMPLW detected in hydrolyzate of CGMP or AYPS presented in hydrolyzed α-la (Table 2). The analysis of peptide sequences revealed the presence of different biopeptides with antioxidant properties (IKH, IPNPIGSE, NEN, AYPS, LLR) in all analyzed hydrolyzate samples (Table 2). However, fermented CGMP was characterized by the largest number of different peptides with antioxidative properties. Moreover, within 21 of various biopeptides identified in this hydrolyzate samples, the potential of their biologically active properties also involved the following activities: antihypertensive, antithrombotic, antibacterial, immuno- and cytomodulatory peptide as well as the function of opioid and ACE inhibitor. Furthermore, the antioxidant peptide IPNPIGSE [αS1 -CN, f(182-189)], previously identified by GÚTIEZ et al. (2013) as a major peptide fragment in supernatants of E. faecalis strains grown in bovine skim milk has also been detected in CGMP hydrolized by the analyzed probiotic L. acidophilus strain. These results are of particular importance in the creation of functional food products. It is claimed that peptide abilities to scavenge free radicals is connected with the presence of hydrophobic amino acid residues like: Met (M), Ile (I), Val (V), Leu (L), Phe (F), Trp (W), Ala (A), Tyr (Y) and Pro (P) (PENA- RAMOS et al., 2004; CHEISON et al., 2007; REN et al., 2008). An example of such peptide sequence is AYPS that was identified in hydrolyzate of α-la. It was also proved that the presence of amino acids with aromatic residues enhances the ability for radical scavenging (RAJAPAKSE et al., 2005). The findings of the investigations indicate that the probiotic strain L. acidophilus LA-5 is also capable of degrading whey and milk proteins and generating peptide sequences exhibited (among others) the ACE-inhibitory activities (Table 2). Obtained results are in accordance with GÚTIEZ et al. (2013), who noticed that proline residue is present in most amino acid sequences of ACE-inhibitory peptides. It was also suggested that this residue is favourable for peptide binding to the active site of ACE. Moreover, GÚTIEZ et al. (2013) identified the peptide LHLPLP that is a competitive inhibitor of ACE exhibiting resistance toward gastrointestinal enzymes (QUIRÓS et al., 2009). Interestingly, another sequence LPYPYY (identified as angiotensin-I-converting enzyme inhibitory peptide) identified in analyzed CGMP hydrolyzates was detected through ESI-MS/MS in samples of yak milk casein hydrolysates exhibiting a high level of ACE inhibition (83.16±1.37 %) (JIANG et al., 2007). Moreover, HERNÁNDEZ-LEDESMA et al. (2007) described the β-lg-derived dipeptide, WY [f(19−20)] as a sequence with ACE-inhibitory bioactivity and radical- scavenging capacity. The same biopeptide was detected in the samples of WPI hydrolyzates obtained using L. acidophilus LA-5 (Table 2). Ital. J. Food Sci., vol. 31, 2019 - 445 Table 1. Texture profiles and spontaneous syneresis levels exhibited by obtained fermented milk products. Added protein preparation Texture parameter Syneresis [%] Hardness [N] Fracturability [N] Springiness Cohesiveness Gumminess Chewiness Control* 0.153±2.59ab 4.59±0.84a 0.82±0.05c 0.45±0.10a 5.32±0.21ab 4.70±0.44bc 19.79±1.86ab CGMP 0.192±0.35a 4.23±1.08a 0.92±0.00ab 0.44±0.09a 7.69±0.45ab 7.32±0.07a 31.79±3.17a WPI 0.128±0.30b 4.25±0.51a 0.99±0.01a 0.64±0.07a 8.26±0.48a 7.59±0.50a 11.27±1.29bc WMP 0.133±1.02ab 5.66±1.04a 0.94±0.03ab 0.55±0.05a 6.43±0.44ab 6.76±0.69ab 7.33±0.08c α-la 0.136±2.37ab 4.11±0.52a 0.94±0.01ab 0.51±0.02a 6.95±1.00ab 6.52±0.96ab 6.95±0.66c WPC30 0.147±2.39ab 3.94±0.40a 0.89±0.01b 0.50±0.07a 5.03±0.86ab 5.91±0.82abc 26.07±3.8a WPC40 0.096±1.00b 5.14±0.49a 0.92±0.01abc 0.49±0.06a 3.97±0.77b 3.73±0.37c 27.63±6.03a *Control - samples consisting of 13% regenerated skim milk without any addition of protein preparation. Differences between mean values (n = 8) ± standard deviation in the same column with the same letter designation are not statistically significant (p <0.05). Table 2. The sequences of biopeptides identified in analyzed hydrolysates obtained using Lactobacillus acidophilus LA-5. Source of peptides (analyzed hydrolysate) Identified peptide sequence Mass (Da) ID of the bioactive peptide in the data base Activity/function reported in the data base CGMP LPYPYY 814.30 biopep00859/BioPepDBb antihypertensive CGMP SPPEIN 655.30 biopep01254/BioPepDB antihypertensive CGMP WPI ERF 450.22 biopep00189/BioPepDB antihypertensive CGMP VRSP 457.26 biopep01460/BioPepDB antihypertensive α-la SRY 424.21 biopep01260/BioPepDB antihypertensive CGMP α-la RPKHPIKHQGLPQEVLNEN 2233.22 biopep01215/BioPepDB antihypertensive CGMP LEQL 501.28 biopep00755/BioPepDB antihypertensive WPI WY 367.15 biopep01540/BioPepDB antihypertensive WPI GKEKV 559.33 biopep00360/BioPepDB antihypertensive WPI VAPFPEVFGKE 1218.63 biopep01336/BioPepDB antihypertensive WPI FVAPFPEV 904.47 biopep00301/BioPepDB antihypertensive CGMP RPK 399.26 biopep01206/BioPepDB antihypertensive WPI VLNENL 700.37 biopep01413/BioPepDB antihypertensive WPI VAPFPEVFGKE 1218.63 biopep01336/BioPepDB antihypertensive WPI LQPEVMGVSK 1086.57 biopep00867/BioPepDB antihypertensive WPI LVYPFPGPI 1001.56 biopep00927/BioPepDB antihypertensive Ital. J. Food Sci., vol. 31, 2019 - 446 CGMP HKEMPFPKYPVEPF 1744.86 biopep00457/BioPepDB antihypertensive CGMP WPI SQSKVLPVPQ 1081.61 biopep01258/BioPepDB antihypertensive WPI LQSW 532.26 biopep00875/BioPepDB antihypertensive CGMP TQSLVYP 806.42 biopep01306/BioPepDB antihypertensive WPI TEDELQDKIHP 1323.62 biopep01279/BioPepDB antihypertensive CGMP WPI MAIPPKK 783.46 biopep00946/BioPepDB 3294/BIOPEP-UWMc antihypertensive, antithrombotic CGMP IPNPIGSE 825.42 biopep00561/BioPepDB antioxidative WPI IKH 396.25 biopep00532/BioPepDB antioxidative CGMP NEN 375.32 9363/BIOPEP-UWM antioxidative α-la AYPS 436.20 8472/BIOPEP-UWM 8380/BIOPEP-UWM antioxidative, ACE inhibitor CGMP WPI LLR 400.28 8484/BIOPEP-UWM biopep00827/BioPepDB antioxidative, antihypertensive CGMP LKTVYQHQKAMKPWIQPKTKVIPYVRYL 3455.96 8337/BIOPEP-UWM antibacterial WPI RELEELNVPGEIVESLSSSEESITR 2801.39 biopep04772/BioPepDB mineral-binding CGMP α-la YQEPVLGPVRGPFPIIV 1880.06 biopep04801/BioPepDB biopep04091/BioPepDB biopep01621/BioPepDB immuno- and cyto-modulatory peptides antimicrobial antihypertensive CGMP NLHLPLP 802.47 2669/BIOPEP-UWM, biopep01010 /BioPepDB ACE inhibitor antihypertensive CGMP WPI VTSTAV 576.30 7481/BIOPEP-UWM biopep01475/BioPepDB ACE inhibitor, antihypertensive α-la LLYQEPVLGPVRGPFPIIV 2106.22 8174/BIOPEP-UWM immunomodulating CGMP TTMPLW 747.30 3530/BIOPEP-UWM, 3127/BIOPEP-UWM, 8172/BIOPEP-UWM, biopep0479 6/ BioPepDB, biopep01313/BioPepDB ACE inhibitor, opioid, immunomodulating immuno- and cytomodulatory peptide, antihypertensive CGMP α-la MAIPPKKNQDKTEIPTINTIASGEPTSTPTTEAVESTVATL EDSPEVIESPPEINTVQVTSTAV 6703.37 biopep03480/BioPepDB antibacterial α-la YYQQKP 825.40 8383/BIOPEP-UWM ACE inhibitor CGMP WPI VQVTSTAV 803.40 biopep01445/BioPepDB, 8264/BIOPEP-UWM antihypertensive, antibacterial bdata base: bis.zju.edu.cn/biopepdbr/ cdata base: www.uwm.edu.pl/biochemia/index.php/pl/biopep Ital. J. Food Sci., vol. 31, 2019 - 447 Hydrolysis of CGMP conducted with the application of the probiotic L. acidophilus strain allowed to receive the sequence TTMPLW exhibited multi-directional biological activities (opioid, ACE inhibitor, antihypertensive, immuno- and cytomodulatory peptide) (Table 2). The results of analysis of ACE-inhibitory and antihypertensive activity in spontaneously hypertensive rats of biopeptides (generated through tripsine hydrolysis of milk proteins) claimed that this sequence was effective in decreasing the level of systolic blood pressure (KARAKI et al., 1990). The concentration of peptide (TTMPLW) needed to inhibit 50% ACE activity (IC50) achieved the value of 16 μM, whereas for sequences LQSW [β-CN, f(155−158)], YQEPVLGPVRGPFPIIV [β-CN, f(208−224)] and MAIPPKK [κ- CN f(106-112)], the IC50 values were 500, 101 and 4785 μM, respectively (KARAKI et al., 1990; MAENO et al., 1996; MIGUEL et al., 2007; HERNÁNDEZ-LEDESMA et al., 2011). All the sequences mentioned above were also identified in whey and milk protein preparations hydrolyzed by L. acidophilus LA-5 (LQSW in samples of hydrolyzed WPI; MAIPPKK in CGMP and WPI hydrolyzates; YQEPVLGPVRGPFPIIV in CGMP and α-la hydrolyzates). The presented results of the research have practical relevance because health-promoting properties provided in food by biopeptides may find an application in personalized nutrition as well as individual dietary practices (KORHONEN and PIHLANTO, 2006). Biologically active peptides are important constituents of food and allow the design of novel foods, including functional food products, supplements, nutraceuticals or even pharmaceuticals (MEISEL, 2005; LIUTKEVIČIUS et al., 2016; LUCARINI et al., 2017). 4. CONCLUSIONS AND FUTURE WORK The obtained study findings demonstrate that analyzed protein preparations are an important source of dietary antioxidants. Furthermore, due to their influence on fermented product, texture properties may find a wider application in the formulation of new dairy products, especially functional food. The use of 1% α-la additive into regenerated skimmed milk is conducive to the reduction of the level of syneresis, with 1% addition of CGMP leaded to obtain the strong, hard gels in fermented milk products, but with a weaker capacity to water-binding. In addition, the hydrolysis process of protein preparations carried out by the probiotic strain improved their antioxidative properties. Furthermore, using the L. acidophilus LA-5 to hydrolysis of CGMP and α-la seems to be an effective method of obtaining products with high antioxidant properties as well as some various biopeptide sequences. Among all analyzed hydrolysates, the sequences with potential antihypertensive activity were the most numerous biopeptides, whereby fermented (by the probiotic L. acidophilus strain) CGMP allowed acquiring the largest amount of different biologically active peptides. However, despite the promising research results, undoubtedly, further investigations are necessary to verify in vivo the biological activity of biopeptide sequences identified in presented study. Also, further analyses might yield new biologically active substances or contribute to a more efficient use of L. acidophilus LA-5 in the production of functional foods, nutraceuticals or pharmaceuticals. Ital. J. Food Sci., vol. 31, 2019 - 448 ACKNOWLEDGEMENTS The research was funded by the National Science Centre, Poland (Research Grant No. 2014/ 15/N/NZ9/04042). REFERENCES Amatayakul T., Sherkat F. and Shah N.P. 2006. Physical characteristics of set yoghurt made with altered casein to whey protein ratios and EPS-producing starter cultures at 9 and 14% total solids. Food Hydrocolloids 20(2-3):314-332. DOI: doi.org/10.1016/j.foodhyd.2005.02.015. Cheison S.C., Wang Z. and Xu S.Y. 2007. Preparation of whey protein hydrolysates using a single- and two-stage enzymatic membrane reactor and their immunological and antioxidant properties: characterization by multivariate data analysis. Journal of Agricultural and Food Chemistry 55(10):3896-3904. DOI: doi.org/10.1021/jf062936i. Creusot N. and Gruppen H. 2007.Protein peptide interactions in mixtures of whey peptides and whey proteins. Journal of Agricultural and Food Chemistry 55(6):2474-2481. DOI: doi.org/10.1021/jf062608i Dąbrowska A., Babij K., Szołtysik M. and Chrzanowska J. 2017. Viability and growth promotion of starter and probiotic bacteria in yogurt supplemented with whey protein hydrolysate during refrigerated storage. Postępy Higieny i Medycyny Doświadczalnej 71:952-959. DOI: doi.org/10.5604/01.3001.0010.5866. Dziuba M., Dziuba B. and Iwaniak A. 2009. Milk proteins as precursors of bioactive peptides. Acta Scientorum Polonorum Technologia Alimentaria 8(1):71-90. Gobbetti M., Stepaniak L., De Angelis M., Corsetti A. and Di Cagno R. 2002. Latent bioactive peptides in milk proteins: Proteolytic activation and significance in dairy processing. Critical Reviews in Food Science and Nutrition 42(3):223-239. DOI: doi.org/10.1080/10408690290825538. Gustaw W., Kozioł J., Radzki W., Skrzypczak K., Michalak-Majewska M., Sołowiej B., Sławińska A. and Jabłońska-Ryś E. 2016. The effect of addition of selected milk protein preparations on the growth of Lactobacillus acidophilus and physicochemical properties of fermented milk.Acta Scientorum Polonorum Technologia Alimentaria 15(1):29-36. DOI: doi.org/10.17306/J.AFS.2016.1.3. Gustaw W. and Mleko S. 2007. The effect of polysaccharides and sodium chloride on physical properties of processed cheese analogs containing whey proteins. Milchwissenschaft 62(1):59-62. Gútiez L., Gómez-Sala B., Recio I., del Campo R., Cintas L.M., Herranz C. and Hernández P.E. 2013. Enterococcus faecalis strains from food, environmental, and clinical origin produce ACE-inhibitory peptides and other bioactive peptides during growth in bovine skim milk. International Journal of Food Microbiology 166(1):93-101. DOI: doi.org/10.1016/j.ijfoodmicro.2013.06.019. Hernández-Ledesma B., Amigo L., Recio I. and Bartolomé B. 2007. ACE-inhibitory and radical-scavenging activity of peptides derived from beta-lactoglobulin f(19-25). Interactions with ascorbic acid. Journal of Agricultural and Food Chemistry 55(9):3392-337. DOI: doi.org/10.1021/jf063427j. Hernández-Ledesma B., del Mar Contreras M. and Recio I. 2011. Antihypertensive peptides: production, bioavailability and incorporation into foods. Advances in Colloid and Interface Science 165(1): 23-35. DOI: doi.org/10.1016/j.cis.2010.11.001. Jeewanthi R.K., Lee N.K. and Paik H.D. 2015. Improved Functional Characteristics of Whey Protein Hydrolysates in Food Industry. Korean Journal for Food Science of Animal Resources 35(3):350-359. DOI: doi.org/10.5851/kosfa.2015.35.3.350. Jiang J.L., Chen S.W., Ren F.Z., Luo Z. and Zeng S.S. 2007. Yak milk casein as a functional ingredient: Preparation and identification of angiotensyn I-converting enzyme inhibitory peptides. Journal of Dairy Research 74(1):18-25. DOI: doi.org/10.1017/S0022029906002056. Jovanović S., Barać M. and Maćej O. 2005. Whey Proteins-Properties and Possibility of Application. Mljekarstvo 55(3):215-233. Ital. J. Food Sci., vol. 31, 2019 - 449 Kabašinskienė A., Liutkevičius A., Sekmokien D., Zaborskienė G. and Šlapkauskaitė J. 2015. Evaluation of the physicochemical parameters of functional whey beverages. Food Technology and Biotechnology 53: 110-115. DOI: doi.org/10.17113/ftb.53.01.15.3763. Karaki H., Doi K., Sugano S., Uchiwa H., Sugai R., Murakami U. and Takemoto S. 1990. Antihypertensive effect of tryptic hydrolysate of milk casein in spontaneously hypertensive rats. Comparative Biochemistry & Physiology969(2):367-371. DOI: doi.org/10.1016/0742-8413(90)90023-3. Korhonen H. and Pihlanto A. 2006. Bioactive peptides: production and functionality. International Dairy Journal 16(9):945-960. DOI: doi.org/10.1016/j.idairyj.2005.10.012. Kullisaar T., Zilmer M. and Mikelsaar M. 2002.Two Antioxidative lactobacilli strains as promising probiotics. International Journal of Food Microbiology72(3):215-224. DOI: doi.org/10.1016/S0168-1605(01)00674-2. Liutkevičius A., Speičienė V., Kaminskas A., Jablonskienė V., Alenčikienė G., Mieželienė A., Bagdonaitė L., Vitkus D. and Garmienė G. 2016. Development of a functional whey beverage, containing calcium, vitamin D, and prebiotic dietary fiber, and its influence on human health. CyTA - Journal of Food 14(2): 309-316. DOI: doi.org.10.1080/19476337.2015.1108366. Lucarini M. 2017. Bioactive peptides in milk: From encrypted sequences to nutraceutical aspects. Beverages 3(3):41. DOI: doi.org/10.3390/beverages3030041. Maeno M., Yamamoto N. and Takano T. 1996. Identification of an antihypertensive peptide from casein hydrolysate produced by a proteinase from Lactobacillus helveticus CP790. Journal of Dairy Science 79(8):1316-1321. DOI: doi.org/10.3168/jds.S0022-0302(96)76487-1. Meisel H. 2005. Biochemical properties of peptides encrypted in bovine milk proteins. Current Medicinal Chemistry 12(16):1905-1919. DOI: doi.org/10.2174/0929867054546618. Michaelidou A.M. 2008. Factors influencing nutritional and health profile of milk and milk products. Small Ruminant Research 79(1): 42-50. DOI: doi.org/10.1016/j.smallrumres.2008.07.007. Miguel M., Manso M.A., López-Fandiño R., Alonso M.J. and Salaices M. 2007. Vascular effects and antihypertensive properties of kappa-casein macropeptide. International Dairy Journal 17(12):1473-1477. DOI: doi.org/10.1016/j.idairyj.2007.04.009. Minkiewicz P., Dziuba J., Iwaniak A., Dziuba M. and Darewicz M. 2008.BIOPEP database and other programs for processing bioactive peptide sequences. Journal of AOAC International 91(4):965-980. Mohanty D.P., Mohapatra S., Misra S. and Sahu P.S. 2016. Milk derived bioactive peptides and their impact on human health - A review. Saudi Journal of Biological Sciences 23(5):577-583. DOI: doi.org/10.1016/j.sjbs.2015.06.005 Nagpal R., Kumar A., Kumar M.Behare P.V., Jain S. and Yadav H. 2012. Probiotics, their health benefits and applications for developing healthier foods: a review. FEMS Microbiology Letters 334(1):1-15. DOI: doi.org/10.1111/j.1574-6968.2012.02593.x. Namdari A. and Nejati F. 2016. Development of Antioxidant Activity during Milk Fermentation by Wild Isolates of Lactobacillus helveticus. Applied Food Biotechnology 3(3):178-186. DOI: 10.22037/afb.v3i3.11422. Osuntoki A. and Korie I. 2010. Antioxidant activity of whey from milk fermented with Lactobacillus species isolated from Nigerian fermented foods. Food Technology and Biotechnology 48(4):505-511. Pena-Ramos E.A., Xiong Y.L. and Arteaga G.E. 2004. Fractionation and characterization for antioxidant activity of hydrolysed whey protein. Journal of the Science of Food and Agriculture 84(14):1908-1918. DOI: doi.org/10.1002/jsfa.1886. Pouliot Y., Guy M.M., Tremblay M., Gaonac’h A.C., Tin B.P.C.P., Gauthier S. and Voyer N. 2009. Isolation and characterization of an aggregating peptide from a tryptic hydrolysate of whey proteins. Journal of Agricultural and Food Chemistry 57(9):3760- 3764. DOI: 10.1021/jf803539f. Quirós A., Contreras M.M., Ramos M., Amigo L. and Recio I. 2009. Stability to gastrointestinal enzymes and structure- activity relationship of β-casein-peptides with antihypertensive properties. Peptides 30(10):1848-1853. DOI:10.1016/j.peptides.2009.06.031. Ital. J. Food Sci., vol. 31, 2019 - 450 Rahmawati I.S. and Suntornsuk W. 2016. Effects of Fermentation and Storage on Bioactive Activities in Milks and Yoghurts. Procedia Chemistry 18: 53-62. DOI: doi.org/10.1016/j.proche.2016.01.010. Rajapakse N., Mendis E., Jung W.K., Je J.Y. and Kim S.K. 2005. Purification of a radical scavenging peptide from fermented mussel sauce and its antioxidant properties. Food Research International 38(2):175-182. DOI: 10.1016/j.foodres.2004.10.002. Ren J., Zhao M., Shi J., Wang J., Jiang Y. and Cui C. 2008. Purification and identification of antioxidant peptides from grass carp muscle hydrolysates by consecutive chromatography and electrospray ionization mass spectrometry. Food Chemistry 108(2):727-736. DOI: doi.org/10.1016/j.foodchem.2007.11.010. Sarkar S., Sur A., Sarkar K., Majhi R., Basu S., Chatterjee K. and Sikder B. 2016. Probiotics: A Way of Value Addition in Functional Food. International Journal of Food Science, Nutrition and Dietetics 5(4):290-293. DOI: dx.doi.org/10.19070/2326-3350-1600052. Skrzypczak K., Gustaw W., Szwajgier D., Fornal E. andWaśko A. 2017. κ-Casein as a source of short-chain bioactive peptides generated by Lactobacillus helveticus. Journal of Food Science and Technology 54(11):3679-3688. DOI: doi.org/10.1007/s13197-017-2830-2. Zhao Q.Z., Wang J.S., Zhao M.M., Jiang Y.M. and Chun C. 2006. Effect of casein hydrolysates on yogurt fermentation and texture properties during storage. Food Technology and Biotechnology 44(3):429-434. Paper Received November 12, 2018 Accepted February 20, 2019