Characterization of partially purified milk-clotting enzyme from sunflower (Helianthus annuus) seeds

Goat Cheese Produced with Sunflower (Helianthus annuus L.) Seed Extract and a Native Culture of Limosilactobacillus mucosae: Characterization and Probiotic Survival

The microbiological and biochemical properties of a goat cheese produced using Helianthus annuus (sunflower) seed extract as a coagulant and the potentially probiotic autochthonous culture Limosilactobacillus mucosae CNPC007 were examined in comparison to a control cheese devoid of the autochthonous culture. Throughout a 60-day storage period at 6 ± 1 °C, lactobacilli maintained a count of above 8 log CFU/g. Additionally, its viability in cheeses subjected to the in vitro gastrointestinal conditions demonstrated improvement over this period. Specifically, the recovery of lactobacilli above 6 log CFU/g was observed in 16.66% of the samples in the first day, increasing to 66.66% at both 30 and 60 days. While total coliforms were detected in both cheese trials, this sanitary parameter exhibited a decline in L. mucosae cheeses during storage, falling below the method threshold (<3 MPN/g) at 60 days. This observation suggests a potential biopreservative effect exerted by this microorganism, likely attributed to the higher acidity of L. mucosae cheeses at that point (1.80 g/100 g), which was twice that of the control trial (0.97 g/100 g). Furthermore, distinct relative proportions of >30 kDa, 30-20 kDa, and <20 kDa proteins during storage was verified for L. mucosae and control cheeses. Consequently, either the H. annuus seed extract or the L. mucosae CNPC007 autochthonous culture influenced the biochemical properties of the cheese, particularly in terms of proteolysis. Moreover, L. mucosae CNPC007 acidification property resulted in a biopreservative effect throughout the storage period, indicating the potential as a promising source of probiotics for this product.

Isolation and identification of milk-clotting proteases from Prinsepia utilis Royle and its application in cheese processing

The aim of this study was to isolate and identify the main milk-clotting proteases from Prinsepia utilis Royle. Protein isolates obtained using precipitation with 20 %-50 % ammonium sulfate (AS) showed higher milk-clotting activity (MCA) at 154.34 + 0.35 SU. Two milk-clotting proteases, namely P191 and P1831, with molecular weight of 49.665 kDa and 68.737 kDa, respectively, were isolated and identified using liquid chromatography-mass spectrometry (LC-MS/MS). Bioinformatic analysis showed that the two identified milk-clotting proteases were primarily involved in hydrolase activity and catabolic processes. Moreover, secondary structure analysis showed that P191 structurally consisted of 40.85 % of alpha-helices, 15.96 % of beta-strands, and 43.19 % of coiled coil motifs, whereas P1831 consisted of 70 % of alpha-helices, 7.5 % of beta-strands, and 22.5 % of coiled coil motifs. P191 and P1831 were shown to belong to the aspartic protease and metalloproteinase types, and exhibited stability within the pH range of 4-6 and good thermal stability at 30-80 °C. The addition of CaCl2 (<200 mg/L) increased the MCA of P191 and P1831, while the addition of NaCl (>3 mg/mL) inhibited their MCA. Moreover, P191 and P1831 preferably hydrolyzed kappa-casein, followed by alpha-casein, and to a lesser extent beta-casein. Additionally, cheese processed with the simultaneous use of the two proteases isolated in the present study exhibited good sensory properties, higher protein content, and denser microstructure compared with cheese processed using papaya rennet or calf rennet. These findings unveil the characteristics of two proteases isolated from P. utilis, their milk-clotting properties, and potential application in the cheese-making industry.

Efficient three phase partitioning of actinidin from kiwifruit (Actinidia deliciosa) and its characterization

Three phase partitioning (TPP) method was effectively utilized for the extraction and purification of milk clotting protease (actinidin) from the kiwifruit pulp. The different purification parameters of TPP such as ammonium sulfate saturation, ratio of the crude kiwifruit extract to tert-butanol, and the pH value of extract were optimized. The 40% (w/v) salt saturation having 1.0:0.75 (v/v) ratio of crude kiwifruit extract to tert-butanol at 6.0 pH value exhibited 3.14 purification fold along with 142.27% recovery, and the protease was concentrated exclusively at intermediate phase (IP). This fraction showed milk-clotting activity (MCA), but there was no such activity in lower aqueous phase (AP). The enzyme molecular weight was found to be 24 kDa from Tricine SDS-PAGE analysis. Recovered protease demonstrated greater stability at pH 7.0 and temperature 50 °C. The Vmax and Km values were 121.9 U/ml and 3.2 mg/ml respectively. Its cysteine nature was demonstrated by inhibition studies. This study highlighted that the TPP is an economic and effective method for extraction and purification of actinidin from kiwifruit, and it could be used as a vegetable coagulant for cheesemaking.

Milk-Gelling Properties of Proteases Extracted from the Fruits of Solanum Elaeagnifolium Cavanilles

There is little information on the milk coagulation process by plant proteases combined with chymosins. This work is aimed at studying the capability of protease enclosed in the ripe fruits of Solanum elaeagnifolium (commonly named trompillo) to form milk gels by itself and in combination with chymosin. For this purpose, proteases were partially purified from trompillo fruits. These proteases had a molecular weight of ~60 kDa, and results suggest cucumisin-like serine proteases, though further studies are needed to confirm this observation. Unlike chymosins, trompillo proteases had high proteolytic activity (PA = 50.23 UTyr mg protein-1) and low milk-clotting activity (MCA = 3658.86 SU mL-1). Consequently, the ratio of MCA/PA was lower in trompillo proteases (6.83) than in chymosins (187 to 223). Our result also showed that milk gels formed with trompillo proteases were softer (7.03 mPa s) and had a higher release of whey (31.08%) than the milk gels clotted with chymosin (~10 mPa s and ~4% of syneresis). However, the combination of trompillo proteases with chymosin sped up the gelling process (21 min), improved the firmness of milk gels (12 mPa s), and decreased the whey release from milk curds (3.41%). Therefore, trompillo proteases could be combined with chymosin to improve the cheese yield and change certain cheese features.

An Easy and Cheap Kiwi-Based Preparation as Vegetable Milk Coagulant: Preliminary Study at the Laboratory Scale

In the present study, a kiwifruit aqueous extract was developed and used as a coagulant enzyme in cheesemaking. In detail, polyacrylamide gel electrophoresis (SDS-PAGE) was used to investigate the presence of actinidin, the kiwifruit enzyme involved in κ-casein hydrolysis, in different tissues (pulp, peel, and whole fruit) of ripe and unripe kiwifruits. Data revealed the presence of the enzyme both in the peel and in the pulp of the fruit. Although the aqueous extract obtained from the kiwifruit peel was able to hydrolyze semi-skimmed milk, it did not break down κ-casein. The aqueous extract obtained from the pulp showed a hydrolytic activity toward both κ-casein and semi-skimmed milk. The values for milk-clotting and proteolytic activity of the kiwifruit pulp extract were evaluated at different temperatures and pH parameters in order to obtain a high value of the MCA/PA ratio; we found that a temperature of 40 °C in combination with a pH value of 5.5 allowed us to obtain the best performance. In addition, the data revealed a higher hydrolytic activity of the enzymatic preparation from ripe kiwifruits than that from unripe ones, suggesting the use of the extract from pulp of ripe kiwifruits in the laboratory-scale cheesemaking. The data showed that 3% (v/v) of the ripe kiwifruit pulp extract determined a curd yield of 20.27%, comparable to chymosin yield. In conclusion, the extraction procedure for kiwifruit aqueous extract proposed in the present study was shown to be a fast, cheap, chemical-free, and ecofriendly technology as a plant coagulant for cheese manufacturing.

Oilseed Extracts from Local Markets as Promising Coagulant Agents for Milk from Various Mammalian Species

The aim of this study was to identify novel milk coagulants to be used in cheesemaking. For this purpose, aqueous extracts from safflower (Carthamus tinctorius), sunflower (Helianthus annuus), flax (Linum usitatissimum) and sesame (Sesamum indicum) seeds were tested for their caseinolytic (CA) and milk coagulating properties (MCA) in skim milk at temperatures of 25, 37, 50, 65 and 80 °C. The seed oil samples with the highest temperature ranges in regard to coagulation efficiency were then tested in cow, buffalo, goat and sheep milks and the MCA and curd yield (CY) parameters were measured at different temperatures. Due to their high milk coagulation efficiency (CE) in all types of milk and at different temperatures, the sesame and sunflower seed extracts proved to be particularly interesting and their CY parameters were similar to those obtained with animal rennet. Moreover, our results confirm that oilseed coagulants are capable of coagulating milk and can also be considered as potential animal rennet substitutes. This study provides valuable insights into the development of potential vegetable coagulants that could be used for various production processes aimed at specific target consumers.

Crystallization of Lactose-Protein Solutions in the Presence of Flavonoids

Lactose is commonly crystallized in the presence of whey proteins, forming co-crystals of lactose and proteins. This work hypothesized that flavonoids such as rutin or epigallocatechin-3-gallate (EGCG) could be incorporated into the lactose and protein co-crystal structure since flavonoids may interact with both lactose and proteins. The interactions between whey proteins and flavonoids were first studied. Then, lactose-protein solutions were crystallized with and without flavonoids, measuring the kinetic parameters of crystallization and characterizing the resulting crystals. The incorporation of flavonoids in lactose-protein co-crystals depended on the hydrophilic nature of flavonoids. The hydrophilic EGCG was scarcely enclosed in the crystal lattice of lactose and avoided the inclusion of whey proteins in the crystals. In contrast, the less water-soluble rutin interacted with whey proteins and lactose, leading to the formation of co-crystals containing lactose, protein, and a large concentration of rutin (3.468 ± 0.392 mg per 100 mg of crystals).

Constitutive expression of Camelus bactrianus prochymosin B in Pichia pastoris

Camel chymosin can be efficiently employed to produce cheese. Traditionally the rennet enzyme produced by the glands of the fourth stomach of ruminant animals (abomassum) is used in cheese making. Full-length Camelus bactrianus (Bactrian camel) prochymosin gene was synthesized and constitutively expressed in Pichia pastoris cells under glyceraldehydes-3-phosphate dehydrogenase (GAP) promoter. It was purified by sequential anion and cation exchange chromatography. SDS-PAGE analysis resulted in two bands, approximately 42 and 35 kDa. The 42 kDa band vanished when the sample was treated with endoglycosidase H, indicating that the recombinant protein is partially glycosylated. Optimal pH for the activity of the highest-purity recombinant chymosin was pH 4.5 for cow's milk and pH 4.0 for mare's milk. The range 45-50 °C and 70 °C for cow's and mare's milk types, respectively, was found to be the most appropriate for maximal relative milk-clotting activity. Concentration of CaCl2 that ensured the stability of the chymosin milk-clotting activity was between 20 and 50 mM with an optimum at 30 mM. Milk-clotting activity of camel recombinant chymosin and ability to make curd was successfully tested on fresh mare's milk. Pichia pastoris strain with integrated camel chymosin gene showed high productivity of submerged fermentation in bioreactor with milk-clotting activity 1412 U/mL and 80 mg/L enzyme yield. These results suggest that the constitutive expression of the camel chymosin Camelus bactrianus in the yeast Pichia pastoris has good prospects for practical applications.

Production, purification and characterization of a milk clotting enzyme from Bacillus methanolicus LB-1

Bacillus methanolicus LB-1 isolated from traditional rice wine was found to produce a milk clotting enzyme (MCE), and its fermentation conditions were optimized using response surface methodology. Then the MCE was produced by ethanol precipitation, and further chromatography separation resulted in a 10.46-fold purification with a 59.28% recovery. The MCA (milk clotting activity) of the purified MCE reached 597,310 ± 0.13 SU/g. The optimal temperature of the MCE was determined to be 50 °C and it was stable in the low temperature range of 40-45 °C. The MCE had an optimum pH of 6.5, and it was stable under neutral conditions. Calcium chloride at the concentration of 25 mM was found to be the most effective stimulus. The MCE was identified by LC-MS to be a putative protein (ID I3EB99) containing 759 amino acids with a molecular weight of 80.37 kDa and a pI of 9.23.

Identification and characterization of N-glycosylation site on a Mucor circinelloides aspartic protease expressed in Pichia pastoris: effect on secretion, activity and thermo-stability

Methylotrophic yeasts have widely been used as model organisms for understanding cellular functions and biochemical activities in lower eukaryotes. The gene encoding an aspartic protease (MCAP) from Mucor circinelloides DSM 2183 was cloned and expressed into Pichia pastoris using both the native M. circinelloides signal peptide (mcSP) and α-factor secretion signal from Saccharomyces cerevisiae (α-MF). When expressed in P. pastoris using α-MF and mcSP, MCAP was secreted into the culture medium at a concentration 200 mg L-1 (410 MCU mL-1) and 110 mg L-1 (249 MCU mL-1), respectively. The SDS-PAGE analysis of each culture shows that the protein was secreted in the media in two forms with molecular weights of approximately 33 and 37 kDa. Upon digestion using endoglycosidase H (Endo H), only one band at 33 kDa was observed, indicating that the protein might be glycosylated. One putative N-glycosylation site was found and a site-directed mutagenesis at position Asn331-Gln of the sequence produce only one form of the protein of 33 kDa, similar to that obtained when digested with Endo H. The optimum temperature and pH activity of the expressed MCAP was found to be at 60 °C and 3.6, respectively.

Utility of Milk Coagulant Enzyme of Moringa oleifera Seed in Cheese Production from Soy and Skim Milks

In this study, the potential use of Moringa oleifera as a clotting agent of different types of milk (whole, skim, and soy milk) was investigated. M. oleifera seed extract showed high milk-clotting activity followed by flower extract. Specific clotting activity of seed extract was 200 times higher than that of flower extract. Seed extract is composed by four main protein bands (43.6, 32.2, 19.4, and 16.3 kDa). Caseinolytic activity assessed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and tyrosine quantification, showed a high extent of casein degradation using M. oleifera seed extract. Milk soy cheese was soft and creamy, while skim milk cheese was hard and crumbly. According to these results, it is concluded that seed extract of M. oleifera generates suitable milk clotting activity for cheesemaking. To our knowledge, this study is the first to report comparative data of M. oleifera milk clotting activity between different types of soy milk.