Effect of water hardness on cooking characteristics of cowpea (Vigna unguiculata L. Walp) seeds

Cowpeas were cooked in water made hard (or soft) by the separate addition of similar concentrations of certain salts (CaCl₂, MgCl₂, or NaHCO₃). The beans were also cooked in hard tap water and in double distilled water before and after soaking in water. Hard water caused a significant decrease in softness, led to reduced water absorption, and also decreased solids loss in the cooked product, but it increased the cooking time and discolouration of the beans. Hard water also gave rise to a significant ( P <0.05) increase in mineral content, but it had less effect on the proximate composition of the cooked products.     

Snap Bean Texture Softening and Pectin Solubilization Caused by the Presence of Salt during Cooking

Special procedures were used to separate the effects on softening and pectin solubilization of the presence of salt during cooking from the effects of salt apart from cooking. The effects of the presence of salt during cooking, calculated with respect to corresponding distilled water cooked beans, were greater with processing conditions of lower blanch temperature and shorter cook times, consequently they were greater with higher canned bean firmness and lower liquor pectin. Neither softening nor pectin solubilization had a significant relation to the reduction in pH induced by NaCl. The softening due to salts was seen with NaCl, KCl, and, to a lesser extent, with CaCl₂, and it may be the result of accelerated degradation of pectins.     

Quality changes and mineral composition of African yam bean (sphenotilis sternocarpa) cooked in kaun (trona) solution

Some quality attributes (cooking time, water absorption and organoleptic qualities), pH, chemical and mineral composition of African yam bean (AYB) cooked in “kaun” solution have been investigated. Cooking in different concentrations of kaun at atmospheric pressure and longer cooking time generally increased water absorption but the optimal cooking conditions (i. e. best kaun concentration and minimum cooking time to achieve optimal quality) were found to be 0.1% and 90 minutes respectively. Cooking in kaun solution of concentration higher than 0.1% caused an unappealing deep brown colour, less number of splitted beans or even no splits and decreased softening of the beans. While cooking in kaun solution at the optimal conditions at atmospheric pressure increased the concentrations of Zn, Ca, Fe, Na and K in both the cooked beans and leached solids, it decreased the concentration of Mg and Cu in the cooked beans. Cooking in kaun solution was also found to produce some little changes in proximate composition. Explanations on the mechanism of softening of the beans in kaun solution were discussed.     

Two Effects of Sodium Chloride Causing Softening of the Texture of Canned Snap Beans

The effect of NaCl on the texture of canned snap beans was studied with leached and nonleached pods. Pectin and Ca solubilization were also measured. NaCl promoted softening both during cooking and apart from cooking. The cooking effect was accompanied by increased pectin solubility. The noncooking effect was accompanied by increased Ca solubility.     

Textural properties and microstructure of low-fat and sodium-reduced meat batters formulated with gellan gum and dicationic salts

Instrumental texture characteristics of low-fat, reduced-sodium meat batters formulated with other salts (KCl and MgCl₂ or CaCl₂) with gellan gum were evaluated. Fat and sodium reduction through incorporation of gellan gum and either of the dicationic salts produced less rigid, more ductile structures. Inclusion of magnesium chloride resulted in better performance, whereas addition of calcium chloride resulted in less desirable properties. The dicationic salts level used probably inhibited the gellan gum thermoreversible properties, affecting its water holding properties. Microstructural differences between the dicationic salt treatments were apparently due to the effect of dicationic salt concentration on myofibrillar protein extraction and solubilization, and gellan gum gelation properties. Use of magnesium chloride in tandem with gellan gum in the studied low-fat, reduced-sodium meat batters effectively compensated for the structural differences caused by fat and sodium reduction.     

Firming of Cooked Sweet Potatoes as Affected by Alum Treatment

Sweet potato slices were cooked for 5 min in distilled water, alum (aluminum potassium sulfate), AICI₃ and several pH level buffer solutions. Slices preheated (60°C) in these solutions were boiled in water. The slices cooked at about pH 4 were firmest among those in the range pH 2-pH 12. Firmness was (greatest to least); preheated in alum > preheated in water > cooked in buffer (pH 3.5) >AICI₃ (pH 3.5) > alum (pH 3.5) > water. Preheating, Al³⁺ and acid prevented softening of slices. Acid-treated slices were firmer than Al³⁺ treated slices. Alum contains K⁺ and S0₄^-2, which accelerate solubilization of pectin, thus slices cooked in alum were softer than those in AICI₃. Scanning electron microscopy showed the middle lamella separated when cooked in water but not when cooked in other solutions.     

The effect of multi-mineral mix (Fe,Zn, Ca and Cu) on magnesium binding to starchy legumes under simulated gastrointestinal conditions

The present in vitro study on starchy legumes and their Mg bioavailability, covers the factors: cooking, dietary fibre, phytic acid and the competitive binding of other minerals. Mg-binding capacity of food legumes (butter beans, broad beans and lentils) in the raw, cooked and fibre-rich fraction (FRF) forms with Mg addition alone and with Ca, Fe, Zn and Cu (at concentrations based on the recommended daily allowance) was investigated in conditions simulating the small intestine. The three legumes in the raw and cooked forms showed more significant (P<0.01) Mg-binding when Mg was added with Ca, Fe, Zn and Cu than with Mg addition alone. The FRFs were found to bind significantly (P<0.01) more Mg than the raw and cooked forms. Cooking significantly decreased (P<0.01) the Mg-binding capacity of raw butter beans, broad beans and lentils at separate Mg addition or with Ca, Fe, Zn and Cu.     

Effect of soaking and boiling treatments on the quality of winged bean seed

Winged bean (Psophocarpus tetragonolobus (L) DC) seeds were soaked for 24 h in distilled water, 30 or 50 g litre^?1 rice husk ash suspension or solutions of 10 or 20 g litre^?1 baking soda, or 5 or 10 g litre^?1 NaHCO₃. Seeds were then boiled for 30 min in these solutions, then either washed and resoaked in distilled water or peeled, washed for 24 h and resoaked for 24 h in distilled water. The p^H and level of leached solids increased during boiling. The colour of the bean cotyledon remained light when boiled in distilled water or rice husk ash suspension, but became darker when boiled in the alkaline solutions. Boiling in distilled water or rice husk ash suspensions did not render the bean sufficiently soft, whereas boiling in the alkaline solutions produced adequately soft seeds. There was no significant difference in tenderness of beans given further processing by resoaking or peeling and resoaking compared with boiling. The nature of the cooking liquid had no significant effect on the protein content of the seeds.     

PECTIC SUBSTANCES OF FABA BEANS AND THEIR RELATION TO TEXTURE OF COOKED BEANS

Twenty samples of faba beans which showed wide variations in texture after cooking were analyzed for total pectin and pectin fractions (i.e., H2O-, EDTA-, and NaOH-soluble fractions) contents of decoated seeds and seed coats. Total pectin ranged between 0.9 and 1.6% of the cotyledons and between 0.5 to 1.0% of the seed coats. Water-soluble pectin was the highest fraction with a mean value about 50% and 40% of the total pectin for the decoated seeds and the seed coats, respectively. No consistent significant correlation was found between the pectic substances fractions and the texture of cooked faba beans for both 1980 and 1981 samples except for the water-soluble pectin as a percentage of the total pectin content of decoated seeds (r = 0.77, P< 0.01 for penetrometer and r =−0.76, P<0.01 for Kramer maximum shear force for 1980 and 1981, respectively).     

Influence of sodium replacement on the salting kinetics of pork loin

The partial replacement of sodium chloride by other salts has been proposed as a possible strategy to reduce the sodium content of cured meat products. Nevertheless, there is very little knowledge as regards the influence of salts other than sodium chloride on salting kinetics.The aim of this study was to evaluate the effect brought about by substituting sodium chloride with potassium, calcium and magnesium chloride on the salting kinetics of dry cured loins. The results showed very important changes in the salting pattern depending on the type of salts. Partial substitution of sodium affected both water and ion transport during the salting process. The presence of KCl decreased water loss while CaCl₂ and MgCl₂ had the opposite effect. However, replacement of up to 50% NaCl by KCl had no significant effect on the salting kinetics in the case of the control formulation. Calcium and magnesium cations penetrated with difficulty into the muscle remaining in the brine formed during the pile salting process. Moreover, the presence of calcium and magnesium cations considerably reduced the sodium and potassium content of the salted loin.     

Influence of the type of calcium salt on the cation absorption and firmness of black ripe olives

The preservation of olives intended for processing as black ripe olives must be done in a salt-free environment although it involves the use of calcium addition to retard olive softening. Calcium chloride and calcium lactate were added by up to 1600 mg Ca L⁻¹ (i) in the preservation liquid of olives before darkening and (ii) in the cover packing brine. The highest texture and calcium absorption were found in the latter case. In addition, the sensory characteristics of the final product were not affected by the use of any of the calcium salts studied at concentrations of up to 1600 mg Ca L⁻¹. Calcium chloride and calcium lactate can be employed to obtain higher texture and calcium content in black ripe olives, although it is advisable to add the cation to the cover packing brine of pitted olives rather than to the preservation liquid.     

Mechanistic insight into common bean pectic polysaccharide changes during storage,soaking and thermal treatment in relation to the hard-to-cook defect

Different mechanisms responsible for the development of the hard-to-cook defect in common beans during storage, their soaking behavior and softening during thermal treatment have been previously suggested. However, these mechanisms have not been sufficiently confirmed by direct molecular evidence. This research aimed at gaining a detailed mechanistic insight into changes occurring in Canadian wonder bean pectic polysaccharides during storage, soaking and/or thermal treatment in different brine solutions in relation to the development and manifestation of the hard-to-cook (HTC) defect. Both fresh or easy-to-cook (ETC) and stored (HTC) bean samples were either soaked or soaked and thermally treated in demineralized water, solutions of Na₂CO₃ and CaCl₂ salts followed by extraction of cell wall materials. Pectic polysaccharide properties examined included sugar composition, degree of methylesterification (DM), extractability and molar mass (MM). The DM of pectin from ETC and HTC beans was similar but low (< 50%). Upon (pre)treatment in a Na₂CO₃ solution, solubilization of pectic polysaccharides, especially the strongly bound chelator- (CEP) and Na₂CO₃- (NEP) extractable pectins was enhanced leading to increased amounts of water extractable pectin (WEP). Also, there was a decrease in high MM polymers paralleled by an increase in β-elimination degradation products. These observations are in line with the fast cooking behavior of beans (pre)treated in a Na₂CO₃ solution. In contrast, (pre)treatment in a CaCl₂ solution hindered softening leading to the failure of the beans to cook. The beans (pre)treated in a CaCl₂ solution showed increased high MM polymers and lack of cell wall separation. Therefore, it can be inferred that development of the hard-to-cook defect in Canadian wonder beans during storage and its manifestation during soaking and subsequent thermal treatment is largely reflected by the pectic polysaccharide properties in line with the pectin hypothesis. Our data suggest the release of Ca⁺⁺ leading to pectin cross-linking and the increase or decrease of β-elimination depolymerization. However, the relatively high amounts of neutral sugars and strongly bound NEP in HTC seeds do not allow to rule out the possible existence of non-Ca⁺⁺ based pectin cross-linking.     

Freezing, thawing and cooking effects on quality profile assessment of green beans (cv. Win)

Results are presented of the effect of freezing followed by thawing (air and water immersion, both at environmental temperature) and cooking (traditional boiling in a covered pot) on quality profile (in terms of objective texture, colour, chlorophylls and pheophytins and sensory attributes) and structure of green beans (cv. Win). Freezing was carried out at three different rates by forced convection with liquid nitrogen vapour. Kramer shear cell (KSC) and Warner–Bratzler (WB) tests were used for objective assessment of the texture. The highest parameter values occurred in beans frozen at the highest rate and air-thawed at the slowest rate. Also, minimum alteration of the rheological behaviour of cooked beans was achieved by freezing at the highest rate. The best parameter for assessing the texture of frozen green beans after thawing and cooking was the Warner–Bratzler slope (S _WB). Coefficients of softening estimated for S _WB in the thawed beans showed that the texture of the beans frozen at −24 °C was almost four and almost five times softer than that of the beans frozen at −70 °C, for air and water thawing respectively. Frozen and thawed green beans were darker than fresh control, whereas freezing prior to cooking produced lighter-coloured beans than direct cooking. The freezing rate affected colour parameters differently depending on the process that followed. When beans were thawed, increasing the freezing rate produced lighter-coloured beans, whereas when beans were cooked, increasing the rate produced darker-coloured beans. No difference was found in sensory assessments between cooked samples frozen at −24 °C, −35 °C and −70 °C, which probably reflects the panellists' mixed preferences for quickly and slowly frozen samples. Scanning electron microscopy (SEM) revealed different degrees of mechanical damage to tissue structure, which accounted for the rheological behaviour of the beans.     

Influence of Soaking and Cooking upon the Softening and Eating Quality of Black Beans (Phaseolus vulgaris)

Soaking and cooking treatments: were evaluated to establish the relationship of various regimes to the development of cooked bean texture and flavor of black beans (Phaseolus vulgaris L.). A salt combination soaking solution was most effective in promoting bean softening during cooking, compared to no soaking or a distilled water soak. A high correlation was observed between objective and sensory texture scores. An Instron puncture force of.150g (0.14 cm probe, 5 cm/min) accurately defined the “eating-soft” limit of texture acceptability.     

The effect of postharvest calcium application on tissue calcium concentration, quality attributes, incidence of flesh browning and cell wall physicochemical aspects of peach fruits

The effects of postharvest calcium applications on cell wall properties and quality attributes of peach fruits (Prunus persica L. Batsch, cv. ‘Andross’) after harvest or cold storage up to 4 weeks were determined. The fruits were immersed in deionised water or in different calcium sources (calcium chloride, calcium lactate and calcium propionate) at two calcium concentrations (62.5 and 187.5 mM Ca). Calcium concentration profiles in fruits (peel and flesh), in cell wall and in pectin fractions were determined. The calcium content in the peel increased up to 2.7-fold, whereas flesh calcium increased up to 74%, 1 day after immersion. The increase of flesh calcium was accompanied by increase of cell wall calcium, which corresponded to a significant increase of calcium in the water-insoluble pectin fraction. However, calcium became saturated in the water-insoluble, but not water-soluble, pectin fraction with 62.5 mM Ca treatment. Treatment with 62.5 mM Ca salts was as effective as higher concentrations of calcium chloride maintaining tissue firmness during storage. Inversely, calcium lactate and calcium propionate at high concentrations (187.5 mM Ca) caused toxicity symptoms on the fruit surface, expressed as skin discoloration and superficial pitting, leading to additional chemical changes and reduced tissue firmness. Postharvest calcium applications limited the intense of chilling injury symptoms, expressed as flesh browning after 4 weeks cold storage. Peach fruits with severe flesh browning symptoms were characterized by reduced ethylene production, and reduced activities of the pectin modifying enzymes poly-galacturonase and pectin-methyl-esterase.     

Effects of Salts and pH on Heating-Related softening of Snap Beans

The effects of salts and pH on softening during cooking were tested by modifying solutions in which pods were heated. Ca displacement was minimized by soaking heated pods in 0.2M CaCl₂ before measuring firmness. Softening was increased independently by the presence of salts and when pH was raised from 5.2 to 6.2. Cations decreased firmness in the order Li > Na = K > NH4 and Ca > Mg. Anions decreased the firmness in the order SO₄ > acetate > CI > NO₃. Firmness differences persisted at long heating times. The results support the hypothesis that pectin β-elimination was the principal softening reaction.     

Effects of Leachate Accumulation During Hydration in a Thermalscrew Blancher on the Water Absorption and Cooked Texture of Navy Beans

Blanch water obtained from a commercial canner was evaluated for leachates that accumulated in a thermalscrew blancher during the rehydration of dried navy beans. These leachates were found to consist of acids, nitrogenous compounds, carbohydrates, and ash. factorial design experiment and a central composite design experiment were conducted to isolate and quantitate the effects of these factors on the water absorption and final texture of navy beans that have been rehydrated in a thermoscrew blancher. Factors of major importance in the soaking water were found to be viscosity, divalent ion concentration, and temperature. Both water absorption and texture of cooked beans responded linearly to these factors.     

Protein and starch content of raw,soaked and cooked beans (Phaseolus vulgaris L.)

Organoleptic qualities are an important factor in the market value of legumes, especially in developed countries. Unfortunately, the molecules that have the greatest influence on the texture of beans undergo important transformations during soaking and cooking. Moreover, the extent to which these changes are linear is unknown, making uncertain the use of raw beans in chemical screenings for sensory properties. Results of our experiments show that the amount of protein and amylose present in raw beans provides a good indicator of these substances in cooked beans (correlation coefficients between raw and cooked beans = 0.91, p ? 0.001 and 0.87, p ? 0.01, respectively). The Mg content in the raw seed coat also shows a strong correlation with that found in the cooked seed coat (r = 0.86, p ? 0.01). The correlations found for the other traits are weaker, indicating that the evaluation of raw samples is not predictive of the findings in cooked beans.     

Synthesis of protodolomite from coral reef sand

Protodolomite (calcium carbonate, PD) is widely used in calcium (Ca) and magnesium (Mg) nutritional supplements because it is rich in Ca (>20%) and Mg (>10%). Synthesis of PD usually involves the use of a NaCl solution with Ca²⁺ and Mg²⁺. In this study, we synthesized PD from coral reef sand (CRS) and magnesium chloride (MgCl₂). First, CRS was dissolved in hydrogen chloride (HCl). MgCl₂ was then added to the solution and the concentrations of Ca²⁺ and Mg²⁺ in the solution were adjusted to 150 and 350 mM, respectively. The solution was mixed with sodium carbonate (Na₂CO₃ = 156 mM) and incubated at 40 °C for 2 days in order to precipitate PD. The precipitate was identified as PD by X-ray diffraction analysis and atomic absorption analysis. This is the first study to synthesize PD from CRS, providing a new source of PD for the food industry.