Heat stability testing

Other tests useful for the detection of unstable hemoglobins are the heat stability test, the Isopropanol precipitation test, and the PCMB or PMB precipitation test ... 

Heinz body preparations are positive as Is the heat stability test Electrophoretic examination of hemolysate showed the presence of a fast-moving variant which was readily separated from Hb-A by chromatography on DEAE-Sephadex The abnormal 3- chain was Isolated by CM-Cellulose chromatography as described before, and converted into the S-2-amlnoethyl (AE) derivative... 

The majority of food flavors are known to be volatile even at ambient temperatures,The molecular entrapment of flavors reduces their equilibrium vapor pressure via fixation in a molecular cavity. The apolar-apolar interaction between the internal wall of the cyclodextrin and the guest molecule results in remarkable heat resistence of volatiles,Signs of this inclusion phenomenon can be seen in heat stability tests. 

Heat Stability Tests at 136° on Double-Base Propellant Formulations Containing Various Tetrazoles and No Other Stabilizer (Ref 4)... 

Ziegelhoffer et al. (15) tested the stability of the apoplast-targeted Elcd in transgenic tobacco plants. In their study, the apoplast-targeted Elcd enzyme extracted from tobacco plants, along with the purified microbial Elcd, was subjected to different temperatures (60-90°C) for 10 min. Both enzymes showed similar high thermal stability throughout the experiment. Their results showed that at 60°C up to 95%, at 70°C up to 90%, at 80°C up to 80%, and at 90°C up to 40% of the enzymes activity was retained. However, as seen in Fig. 4, our heat stability test showed sur-... 

The stability of the caseinate particles in milk can be measured by a test such as the heat stability test, rennet coagulation test, or alcohol stability test. Addition of various phosphates—especially polyphosphates, which are effective calcium complexing agents—can increase the caseinate stability of milk. Addition of calcium ions has the opposite effect and decreases the stability of milk. Calcium is bound by polyphosphates in the form of a chelate, as shown in Figure 5-3. 

It is important in this or any other heat stability test to mold the natural resin as a control. Some resins, especially acrylonitrile butadiene styrene (ABS), darken considerably when heated above a particular threshold temperature. In the case of ABS, the butadiene rubber component may begin to go yellow and dark over 450°F. Although the customer may set its machines below 450°F barrel temperatures, shear heating or heating in the hot runner manifold could yield local melt temperatures in excess of 500°F and burn the natural resin. 

Therefore, an alternative test method, such as heating at 80 °C for 2 h, an alkali modified Coomassie-dye assay (e.g. Boyes et al. 1997), or the more recently available reagent based test kits such as Proteotest or Prostab, could present an opportunity to decrease bentonite dose and reduce volume of wine occluded in bentonite lees if confirmed to predict more accurately haze formation in wine. If these alternative test methods could replace the current heat test method of 80 °C for 6 h, this would also reduce the amount of time and/or effort presently required by a winery s laboratory to conduct heat stability testing. 

Polyacrylamide gel electrophoresis (PAGE) revealed that fining removed low molecular weight (<31,000) protein bands(5). Juice from long-term stored fruit had fewer bands (5). A heat stability test showed that juice from long-term stored fruit had more of a tendency to form haze than juice from short-term stored fruit. 

A typical heat-stability test would involve incubation of the sample at 80/90°C for 10 min in a water bath (taking into account loss of volume or any physical changes in the sample, e.g., clotting, aggregation), then assay for the unaffected compound. This is most appropriate for biological assays as it may be difficult to detect breakdown of a compoimd in a mixture by physical means. 

An alternative to the torque rheometer for dynamic heat stability testing of plastieized PVC is a two-roll mill. Measuring the time taken for the onset of sticking to the mill surface avoids serious chlorine evolution and can be used for any color, but it relies much on operator judgment. 

Heat stability test n. An accelerated test used to predict viscosity stability of coatings with time. The test generally involves measuring viscosity change after the paint has been heat-aged about a week to 10 days at 50-60°C. An excessive increase in viscosity is unacceptable. 

It has been pointed out that cyclodextrin complexa-tion significantly improves the thermal stability of volatile, oxydizable active ingredients of suppositories The results of the heat—stability tests are summarized in table II ... 

TABLE 60 Heat Stability Test Results of Acid-Thickened Formuna... 

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