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

Symbiotic sheep milk cheese containing Moringa oleifera extract and Bifidobacterium pseudolongum INIA P2

Healthy non-bovine functional dairy products are reaching high interest among consumers. In the present study, an aqueous polyphenol-rich Moringa oleifera extract (MoE) and a Bifidobacterium strain of human origin (B. pseudolongum INIA P2) were added, alone or in combination, for the manufacture of three experimental and one control sheep milk cheeses. In general, addition of 2.05 g of lyophilized MoE per 100 g of curd did not affect cheese dry matter or lactococci starter counts during ripening. B. pseudolongum INIA P2 showed good viability in cheese during ripening, and after simulated major gastrointestinal conditions, reaching levels above 7 log CFU / g of cheese. Cheeses with MoE showed lower pH, higher proteolysis and aminopeptidase activity than control cheese. MoE impoved functional properties, significantly (P < 0.01) increasing total phenolic content (TPC) and, especially, antioxidant capacity, with respect to control cheese. MoE modified cheese colour and volatile profile. Cheeses with MoE were darker in colour with higher red and yellow components than control cheese. Several volatile compounds were only detected in cheeses with MoE, indicating their plant origin. On top of that, increased levels of compounds originating from amino acid catabolism were present in these cheeses, as a result of their higher proteolytic and peptidolytic indexes. The symbiotic cheese with MoE and B. pseudolongum INIA P2 could confer beneficial effects on consumers' health by increasing polyphenol bioavailability and contributing to the host antioxidant capacity.

Improvements of virulence factor phenotypic tests for Aeromonas salmonicida subsp. salmonicida, a major fish pathogen

Aeromonas salmonicida subspecies salmonicida, a fish pathogen, expresses various virulence factors such as an A-layer, lipases and proteases during the infection process. Not all strains of this bacterium express the same virulence factors. It is important to be able to evaluate which factors are present when characterizing strains. The A-layer and secreted lipases and proteases are usually detected by agar-based tests that require long incubation (24 h and more) and may provide ambiguous results. In the present study, protocols have been optimized to determine the presence of these virulence factors using liquid tests. For A-layer detection, the optimized method stains the positive bacteria with Coomassie Brilliant Blue. The lipases are detected by a colorimetric biochemical reaction triggered by the degradation of p-nitrophenyl dodecanoate into a yellow product detectable by spectrophotometry, if the result is positive. Both of these tests show results in less than an hour. Finally, the protease activity is measured by clarification of a medium containing milk during an overnight bacterial growth. These new protocols provide opportunities for quicker characterization of A. salmonicida subsp. salmonicida strains and, particularly, provide more precise results.

Structural Analysis of a Novel Aspartic-Type Endopeptidase from Moringa oleifera Seeds and Its Milk-Clotting Properties

A novel aspartic-type endopeptidase was previously obtained from Moringa oleifera seeds; however, its specific milk-clotting properties have remained unclear. Here, we used various biophysical and molecular simulation approaches for characterizing the structure and function of the aspartic-type endopeptidase. The endopeptidase was preferentially active toward κ-casein (CN) and hydrolyzed it more than calf rennet; however, its ability to hydrolyze α-CN and β-CN was weaker than that of calf rennet. The endopeptidase cleaved κ-CN at Gln135-Asp136 and generated a 15 588.18 Da peptide with 135 amino acids. We further simulated the docking complex of the endopeptidase and κ-CN and found out that they possibly combined with each other via hydrogen bonds. The flocculation reaction between the endopeptidase and κ-CN indicated that milk coagulation occurred within 60 min. Overall, our observations suggest that the aspartic-type endopeptidase can be a potential rennet alternative for cheese making.

Production of a New Plant-Based Milk from Adenanthera pavonina Seed and Evaluation of Its Nutritional and Health Benefits

A new plant milk was discovered from the seed of Adenanthera pavonina. The physicochemical and nutritional properties of the new pro-milk extract were assessed, and their biochemical effects were compared with those of soy bean extracts. Eleven groups of three albino rats each were used to assess the health benefits of the pro-milk. Groups were separately administered 3.1, 6.1, and 9.2 µl/g animal wt. pro-milk extract from A. pavonina seed, 6.1 µl/g animal wt. milk extract from soybean, and 6.1 µl/g animal wt. normal saline for 7 or 14 days. The “baseline” group consisted of those sacrificed on day 0. Among the physical properties considered, the pro-milk from A. pavonina had significantly higher (P < 0.05) hue color value and significantly lower (P < 0.05) L* than that from soy bean did. The pro-milk from A. pavonina had a significantly higher (P < 0.05) level of protein (36.14 ± 0.12%), Ca (440.99 ± 0.93 mg/l), Mg (96.69 ± 0.03 mg/l), K (190.41 ± 0.11 mg/l), Na (64.24 ± 0.24 mg/l), and Cu (0.55 ± 0.24 mg/l), and a significantly lower (P < 0.05) level of Mn (0.04 ± 0.01 mg/l) and vitamins A (undetectable), C (1.87 ± 0.01 mg/100 g), and E (0.12 ± 0.01 mg/100 g) compared to those of soy milk. The daily consumption of the pro-milk extract from A. pavonina for 14 days significantly reduced (P < 0.05) Ca²⁺-adenosine triphosphate synthase (Ca²⁺-ATPase) at low dose (3.1 µl/g animal wt.), but significantly increased (P < 0.05) Mg²⁺-ATPase at high dose (9.2 µl/g animal wt.). Daily administration of the A. pavonina extract for 14 days caused a significant reduction (P < 0.05) in acetylcholinesterase activity in the liver, intestine, heart, and kidney, suggesting that the pro-milk may facilitate ions transportation across the membrane. The pro-milk offers promising beneficial effects for patients with neurological diseases, as well as supporting general health owing to the high protein and mineral content. Vitamins fortification is recommended during production.