Authors:C. Ferrero, M. N. Martino, and N. E. Zaritzky
Differential scanning calorimetry (DSC) was used to analyze the influence of different hydrocolloids (xanthan, guar, and locust bean gums, carboxymethylcellulose and sodium alginate) on the gelatinization of corn starch in systems with starch concentration ranging between 0.1 and 0.7 g starch/g mixture. The reduction of available water produced a shift in gelatinization temperature, especially of the conclusion temperature. The effect was more marked for ionic hydrocolloids. The influence of hydrocolloids on glass transition temperature (Tg) of gelatinized starch suspensions and on the glass transition temperature of the maximally freeze-concentrated solute/unfrozen water matrix (T′g) was also studied.T′g onset values ranged between −4.5 and −5.5‡C for corn starch pastes with and without hydrocolloids. Those hydrocolloids that increased the viscosity of the unfrozen matrix inhibited additional ice formation during thawing (devitrification).
Ribotta, P.D., Perez, G.T., Leon, A.E., Anon, M.C. 2004. Effect of emulsifier and guar gum on micro structural, rheological and baking performance of frozen bread dough. Food Hydrocolloids
While the basic fermented (sour) milk products, such as yogurt and kefir can be produced only in live flora version, the post
heat-treatment is preferred in their flavored variations to increase the storage time. Casein being in sour coagulum precipitates
during heat-treatment; therefore protective colloids surrounding the protein should be used to prevent it. Protective colloids
are plant extracts, the most known of them are pectin and amylopectin. Basic requirement of protective colloid effect is the
lower swelling temperature of hydrocolloid than the temperature of precipitation of sour coagulum. In this work we have examined
the precipitation of sour coagulum as a function of the type of lactic acid bacteria cultures applied during fermentation
as well as the swelling of heat protective plant hydrocolloids as a function of the composition (mainly of sugar content)
of medium. To investigate the precipitation of fermented coagulum skimmed milk was fermented with mesophilic butter culture,
thermophilic yogurt culture as well as with exopolysaccharide (EPS)-producing Prebiolact-2 culture. Precipitation was indicated
in the increase of great extent of viscosity. Amylopectin was dispersed into aqueous solution of pH 4.5, the saccharose concentration
of which was changed during the investigation of the swelling of heat protective hydrocolloids. A definite exothermic peak
was assigned to the swelling of hydrocolloids during the DSC experiments. We could conclude that the precipitation temperature
was increasing in the mesophilic-thermophilic-EPS producing microbes line, i.e. the heat stability and swelling temperature
of hydrocolloids depend on the saccharose content of aqueous medium and they increase with rising the concentration of saccharose.
In this study, the effects of 18 different additive formulas constituted with xanthan and hydroxypropylmethylcellulose (HPMC) gums (hydrocolloids) were examined in the manufacture of corn starch based gluten-free bread. The additives used as alone or in combinations in the bread manufacture. It was also added with mono- and diglyceride based gel preparations and diacetyl tartaric acid esters of mono- and diglycerides for improving glutenfree bread characteristics. The volumes and softness of the breads have been measured as maximum when HPMC was used alone in increasing order from 1 to 2%. While HPMC gum improved the volume and softness of bread more than Xanthan gum, Xanthan gum improved the grain structure of crumb more than HPMC. In general, these hydrocolloids gave a good quality of bread in terms of moisture content, grain structure and Neumann baking coefficient values, when they were used with combinations rather than being used individually. Addition of surfactant to all combinations always enhanced the grain structure of bread. In contrast, it either worsened or did not change the volume and softness of the bread.
In contrast with the traditional method of cheese processing, where Ca breaks down from the protein chain and protein is peptized,
a new technology has been elaborated, during which cheese is dispersed without phosphate-containing processing salt, when
the gel is formed by plant hydrocolloids.
Raw material of constant composition was processed with a phosphate-containing salt or in the presence of hydrocolloids. Thermodynamic
processes occurring during the processing and in the end-products were examined by an ultra-sensitive micro DSC method. The
structures of end-products were also investigated by electronmicroscopy.
The temperature ranges of the endothermal processes indicating the transformations of protein and hydrocolloids can be distinguished:
81-90C for peptization processing and 61-72C for processing without peptization. The differences are less in the end-products:
75-87C in traditional processed cheese and 68-74C in processed cheeses made without peptization. In contrast with the spongy
structure of traditional processed cheeses consisting of peptized proteins, processed cheeses made without peptization involve
structure-forming elements created by the interaction of linear macromolecules of hydrocolloids and cheese proteins.