Adjunctive Application of Solid-State Culture Products from Aspergillus Oryzae for Semi-Hard Cheese

Abstract

To develop a novel type of cheese using Aspergillus oryzae, four strains (AHU 7139, AHU 7140, AHU 7141 and AHU 7146) were tested with respect to their extracellular protease production on solid-state media containing heatdenatured whey protein under various temperatures and pH levels. Proteolytic activity of the crude enzyme extracts was evaluated under acidic condition considering the circumstance of cheese ripening. Zymographic analysis revealed that several kinds of proteases were secreted, which were dependent on the strain, incubation temperature and initial pH value. Using three strains, six types of culture products were selected as adjunctive materials in combination with an incubation temperature of 15 or 20ºC and an initial pH condition of 4.0 or 6.5. Gouda-type cheese curd was prepared, and the curd particle received 1% (w/w) of the culture product, followed by pressing, cooling, salting and ripening for 3 months at 11.5ºC. An increase in water extractable nitrogen and free fatty acid was observed in some experimental cheeses, depending on the strain and culture history. In particular, incorporation of culture products from A. oryzae AHU 7139, incubated at pH 6.5 and 20ºC affected these parameters. As a novel dairy technology, this study propose new insights into the potential use of A. oryzae for providing an enzyme cocktail to develop palatable cheese flavor when suitable strains and culture conditions offer products with an optimum balance of proteases and lipases.

Application of red pigment producing edible fungi for development of a novel type of functional cheese

“…Our previous study reported that a specific culture product from A . oryzae AHU 7139 on WPC solid medium to cheese curd caused intense rancid in three‐month‐aged cheese products (Kumura et al, ). In contrast, negligible difference of FFA content between control and red mold cheese was recognized, which demonstrated that influence of lipolytic system of Monascus could be excluded.…”

‘Lipase and protease production of dairy Penicillium sp. on milk‐protein‐based solid substrates’

“…Raw milk obtained from the experimental farm in the Field Science Center for Northern Biosphere at Hokkaido University was mixed with skim milk to adjust its fat content of 2.8~3.0 g/100 g. Following procedures, including pasteurisation at 72°C for 15 s, the starter addition, chymosin treatment and subsequent gentle stirring, were performed as previously described (Kumura et al 2017). Ten grams of the recovered curds in 1-cm 2 cubes was transferred into an Erlenmeyer flask (100 mL) and autoclaved at 121°C for 15 min to use as the simulated cheese medium.…”

“…Proteolytic activity was determined as previously described (Kumura et al 2017). As the substrate, 0.2 g of casein was dissolved in 100 mL of 0.05 M sodium phosphate-citric acid buffer (pH 5.5 and 7.0) or 0.05 M Tris-HCl buffer (pH 7.0 and 8.5).…”

“…On the other hand, our previous study reported the application of the culture products of Aspergillus oryzae for cheesemaking, as an adjunct enzyme cocktail, to enrich its flavour (Kumura et al 2017). Since solid cultivation is superior to a submerged culture in terms of the enzyme productivity of filamentous fungi, heatdenatured whey protein concentrate (WPC) was used to prepare a solid culture substrate.…”

Adjunctive application of solid‐state culture products and its freeze‐dried powder from Aspergillus sojae for semi‐hard cheese

“…It is known that a solid culture is superior to a liquid one for enzyme production by filamentous fungi. In our previous study, 2 whey protein concentrate (WPC) was used as a solid substrate for A . oryzae , and the culture products (CPs) were mixed with fresh cheese curds prepared under the procedure for traditional semihard‐type cheese making.…”