Foam volume

Fig. 35. Maximum foaming volume of styrene diviaylben2ene copolymers containing 8.8 wt % CO2 as a function of divinylben2ene content and temperature. Numbers beside curves indicate wt % divinylben2ene, VJVthe ratio of final volume to initial volume at temperature t (258).

Foam regulators such as amine oxides, alkanolamides, and betaines are present in products where high foam value is functionally or estheticaHy desirable, mainly hand-dishwashing Hquids and shampoos. In automatic dishwashing products, on the other hand, copious foam volumes interfere with the efficiency of the mechanical rotors during operation. In this type of product, a foam depressant is often present. 

The foam volume and stability of alcohol sulfates is relatively increased in hard water compared to soft water. The amount and quality of foam is dependent on the alkyl length. Sulfates with C12-C,4 alkyl chains produce the richest creamy foam with small bubbles. C8-C10 alcohol sulfates are foam depressants and C16-C18 alcohol sulfates are poor foaming surfactants. Foams produced by alcohol sulfates are also relatively stable in the presence of sebum. Sodium and ammonium alcohol sulfates foam better than triethanolamine alcohol sulfates. Alcohol ether sulfates produce lighter foams than those of alcohol... 

C. Among sodium salts, hexadecyl sulfate gave a maximum foam volume, above 700 cm3, at 75 °C while at 50°C the maximum corresponds to tetradecyl sulfate but, as expected, with a lower volume (around 550 cm3). The fact that solubility in water decreases as the chain length increases can explain the progressive displacement of the maximum to higher homologs as the temperature increases. 

Surfactant Parent olefin Foam volume after x minutes, x =... 

Fig. 7 Stabilization effect of various xylan types isolated from beech wood (GXl and GX2), corn cobs (AGXl), rye bran (AXRl and AXR3), and corn hulls (AXCl and AXC2) on the protein (BSA) foam against thermal disruption foam volume before (V1) and after (V2) heating at 95 °C for 3 min [128]...

Extrusion cook temperature Moisture (%) Gel strength (N) Foam volume (%) Foam stability... 

WPI Whey protein isolates. Properties of nonextmded WPI moisture 1.94%, gel strength 52.3 (N), foam volume 288%, and foam stability 28.7%. Value not reported. Means with different letters within a column are significantly (p < 0.05) different. 

Incomplete texturization or partial denaturation at temperatures below 60 °C significantly increased gel strength, but at 75 °C or above, complete loss of the gelling property resulted. Foam volume remained high up to 50 °C but decreased significantly (p < 0.05) above 75 °C. Foam stability followed the same pattern as foam volume, being very stable for an hour below 50 °C. On the contrary, Phillips et al. (1990) reported that WPI heated to 80 °C had little effect on foam stability. 

Foam Volume in cm Determined with the Beating Method Using a Perforated Disk after 30 sec. at 40°C, 1 g/1... 

Cosmetic Rinse off Preparations. In certain cosmetic products, tor example hair shampoos, it is not possible to use complexing agents because of the irritation of mucous membranes. Here a low sensitivity of surfactants to water hardness is a precondition for their application. Foam formation is generally considered to be a measure of shampoo quality (Table V). With increase in water hardness the foam volume of alkyl sulfates decreases very much, whereas with the corresponding alkyl ether sulfates this decrease is relatively small. For cosmetic applications, the good skin compatibility and low irritation to mucous membranes of alkyl ether sulfates is of high importance (37). 

Whipping produces foams that can be measured by the increase in foam volume, specific gravity, and viscosity (15,... 

The stability of foams is usually measured by the volume of liquid drained from a foam during a specific time at room temperature (10. 15. 17) or by a decrease in foam volume over time. Methods employed to measure foam stability include the rate of fall of a perforated weight through a column of foam (20. 22), the penetration of a penetrometer cone (17), or the ability to support a series of specific weights (277. 

Limited digestion of globular soy proteins with rennin affords a modified protein preparation which retains a high molecular weight (47). Whipping quality, measured by foam volume and stability, was superior in comparison with native proteins. The limited rennin proteolysis of soy was identified as a key factor in functionality, since this modification conferred improved solubility. 

Pepsin and papain hydrolysates of rapeseed protein concentrate increased foam volumes and decreased drainage compared to the untreated control (36). Foaming properties could be further enhanced by adding a stabilizer such as carboxymethylcellulose. 

A limited amount of hydrolysis appears to be desirable to increase foam volume but foam stability is greatly decreased as a result of such hydrolysis. The authors suggest that this is probably due to... 

Additives had substantial effects on the aeration properties of bromelain-modified succinylated fish protein (50). Foam volume was increased with up to 2% sodium chloride in the system however there was a decrease in foam stability when greater than 0.3% salt was used. Sucrose, at concentrations up to 50%, increased foam stability. When fat was added to treated fish protein dispersions... 

We prefer an alternative model. The expansion of the foam doubtless takes place in a high-viscosity environment. Expansion of the individual cells and a corresponding increase in foam volume continue until the transition from liquid flow to gelation. At this point, the windows between the cells are stretched beyond their elastic limit and therefore burst instead of continuing to flow. Examination of a closed-cell foam shows that the windows do indeed rupture as opposed to opening through viscous flow. 

Foamability Foam volume generated under a fixed set of conditions from a fixed amount of liquid. Endpoint can be based on foaming time or maximum sustainable foam volume. Methods to monitor foam volume and express foamability vary. Volume can be determined in a graduated cylinder. Alternatively, foam expansion is calculated by dividing the weight of foam by the weight of solution at constant volume. 

Foam volume stability Change in foam volume with time Stability is often expressed as half-life of the loam. The half-life is defined as the time for half the liquid to drain or half the foam to collapse. 

Foamability, foam volume, and bubble size in protein analysis, 297 (table)... 

Here, foam is generated by flowing gas through a porous orifice into a test solution as shown in Figure 2.17. The steady-state foam volume maintained under constant gas flow into the column is then measured. There are many variations of this kind of test [46,115,116], This technique is frequently used to assess the stability of evanescent foams. 

In foaming, the ratio of foam volume produced to the volume of liquid used to make the foam. Also termed the expansion ratio . 

A relative drainage rate test in which a foam is formed in a vessel and thereafter the remaining foam volume is determined as a function of time. The foam number is the volume of bulk liquid that has separated after a specified interval, expressed as a percentage of the original volume of liquid foamed. 

Foam Properties. A previous paper(1) reported that SAE show better foam breakability than PAE or NPE. This tendency becomes clearer when SAE and PAE having lower carbon number ranges are compared. Figure 9 and Figure 10 show foam volume vs. concentration in an agitation test for C2.2-14 EAE E0 C10-12 AE(9E0) anc PAE(8E0) in the initial stage and after five minutes,... 

Figure 9. Effect of carbon number range on foam volume (initial stage) ((- -) C10.lt SAE (9EO) (-%-) Clt.H SAE (9EO) (-A-,) C9 + 11PAE (8EO))...

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