Factors Affecting Stability of Rennin

Mickelsen, R.; Ernstrom, C.A.

doi:10.3168/jds.s0022-0302(67)87485-x

Cited by 21 publications

(7 citation statements)

References 12 publications

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“…Thermal denaturation of chymosin is dependent on pH (Farkye & Imafidon, 1995), ionic strength (Larson & Whitaker, 1970) and the total solids content of the system (Verhey, 1973). Substances such as sugars, proteins and calcium increase the thermostability of chymosin (Van de Beek & Gerlsma, 1969), while NaCl and urea decrease its thermostability (Mickelsen & Ernstrom, 1967).…”

mentioning

confidence: 99%

Thermal inactivation of chymosin during cheese manufacture

Hayes

Oliveira

McSweeney

et al. 2002

Journal of Dairy Research

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The aspartic proteinase, chymosin (EC 3.4.23.4) is the principal milk clotting enzyme used in cheese production and is one of the principal proteolytic agents involved in cheese ripening. Varietal differences in chymosin activity, due to factors such as cheese cooking temperature, fundamentally influence cheese characteristics. Furthermore, much chymosin is lost in whey, and further processing of this by-product may require efficient inactivation of this enzyme, with minimal effects on whey proteins. In the first part of this study, the thermal inactivation kinetics of Maxiren 15 (a recombinant chymosin preparation) were studied in skim milk ultrafiltration permeate, whole milk whey and skim milk whey. Inactivation of chymosin in these systems (at pH 6.64) followed first order kinetics with a D45.5 value of 100±21 min and a z-value of 5.9±0.3 °C. D-Values increased linearly with decreasing pH from 6.64 to 6.2, while z-values decreased as pH decreased from 6.64 to 6.4, but were similar at pH 6.4 and 6.2. Subsequent determination of chymosin activity during manufacture of Cheddar and Swiss-type cheese showed good correlations between predicted and experimental values for thermal inactivation of chymosin in whey. However, both types of cheese curd exhibited relatively constant residual chymosin activity throughout manufacture, despite the higher cooking temperature applied in the manufacture of Swiss cheese. Electrophoretic analysis of slurries made from Cheddar and Swiss cheese indicated decreased proteolysis due to chymosin activity during storage of the Swiss cheese slurry, but hydrolysis of sodium caseinate by coagulant extracted from both cheese types indicated similar levels of residual chymosin activity. This may suggest that some form of conformational change other than irreversible thermal denaturation of chymisin takes place in cheese curd during cooking, or that some other physico-chemical difference between Swiss and Cheddar cheese controls the activity of chymosin during ripening.

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mentioning

confidence: 99%

Thermal inactivation of chymosin during cheese manufacture

Hayes

Oliveira

McSweeney

et al. 2002

Journal of Dairy Research

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“…Long extraction time had a negative effect on the activity and yield of prochymosin. According to Mickelsen and Ernstrom (1967), during extraction, chymosin was partially inactivated because of its low stability in an aqueous medium.…”

Section: Results and Discussion Control Methods Of Prochymosin Extractionmentioning

confidence: 99%

“…Chymosin is a very heat stable enzyme at pH values between 5.3 and 6.3 (Foltmann, 1959;Mickelsen and Ernstrom, 1967). Generally, during extraction of biologically active substances, yield increases with increasing temperature because of the increasing diffusion rate.…”

Section: Fig 4-prochymosinmentioning

confidence: 99%

Processing Parameters of Chymosin Extraction by Ultrasound

Kim

Zayas

1989

Journal of Food Science

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Control method for chymosin productionConventional chymosin (rennin) production requires a prolonged cxtraction. An ultrasound method of chymosin extraction was dcvcloped for increased efficiency. Ultrasound extraction was carried out with Tekmar sonic disruptor (TK 1000) and Lauda circulator. Control cxtraction was carried out by shaking. The USC of ultrasound rcsultcd in a significant reduction of extraction time with increases in activity and yield of chymosin. The optimal parameters for ultrasound extraction were: specific intensity, 36 W/cm2 at 20 kHz frequency; time of exposure, 80 min; temperature, 25°C; ratio of abomasa to extraction solution, 1:25; and activation time of prochymosin, 13.0-13.5 hr.

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“…A proportional pH decrease was experienced with increasing S gf in batch mode, but when switched to continuous operation the pH eventually reached 4.8±5.2. This range has been reported in the literature as the most stable pH range for minimum activity loss at various temperatures 8,18 and the pH data for S gf in the range 2.5±7.5 g dm…”

Section: Variation Of Medium Phmentioning

confidence: 99%

The effect ofD-glucose on milk clotting activity ofMucor miehei in a chemostat with biomass retention

Beyenal

Şeker

Salih

et al. 1999

J. Chem. Technol. Biotechnol.

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In this study microbial production of rennin from a commercial strain of Mucor miehei (NRRL 3420) has been accomplished in a continuously fed fermenter. The effects of feed D-glucose concentration (2.5±30 g dm À3) on milk clotting activity and on other system variables were investigated at optimum mixing and dilution rates of 400 rpm and 0.0052 h À1 , respectively, without pH control. Maximum milk clotting activity (1.24 IU cm À3) occurred when the feed D-glucose concentration was 7.5 g dm À3. Enzyme production continued for 500 h, producing a total milk clotting activity of 10 230 IU. At the maximum milk clotting activity point, total protein concentration, milk clotting and proteolytic activities were analysed and compared with those of a commercial rennet. The ratio of milk clotting activity to proteolytic activity, and speci®c milk clotting activity were determined as 1.55 Â 10 À3 IU PU À1 and 5.28 IU mg À1 medium protein, respectively, denoting similar characteristics to a commercial rennet after concentration of the fermentation medium.

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Factors Affecting Stability of Rennin

Cited by 21 publications

References 12 publications

Thermal inactivation of chymosin during cheese manufacture

Thermal inactivation of chymosin during cheese manufacture

Processing Parameters of Chymosin Extraction by Ultrasound

The effect ofD-glucose on milk clotting activity ofMucor miehei in a chemostat with biomass retention

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