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.     

Retarding Vegetable Softening by Cold Alkaline Pectin Deesterification Before Cooking

Snap beans and carrot tissues, deesterified at 1°C and pH 12.5, soften much more slowly than control tissues when cooked at neutral or slightly alkaline pH. High pH or NaCl during cooking had little effect on the degree of softening. Soaking in 0.05 M EDTA led to an 86% loss in firmness. The results were consistent with a reduction in the β-elimination depolymerization of pectin during heating as a result of deesterification in the alkali. Deesterified tissues remained susceptible to pronounced softening during cooking at pH 3.5. Potatoes, cauliflower and apples showed similar effects. Peas gave a reduced response. Beets and dry beans did not show a retardation of softening after an alkali soak.     

Softening Effects of Monovalent Cations in Acidified Cucumber Mesocarp Tissue

Due to the importance of salt as an ingredient in cucumber pickle products, the effect of salt concentration on first-order softening rates during acid storage was determined. Softening rates of unfermented tissue increased as the NaCl increased from 0 to 1.5M, whether or not the tissue was blanched. For unheated, fermented tissue, softening rates increased between 0 and 0.2M NaCl but did not increase above 0.2M NaCl. Changes in the degree of pectin methylation were not highly correlated with changes in softening rates. The ions Li⁺, K⁺, Rb⁺, and Cs⁺ had softening effects similar to Na⁺. An enthalpy of activation of 145 kJ/mole was determined for softening of blanched tissue stored in 1.5M NaCl. This is the first demonstration of a softening effect by monovalent cations in cucumber tissue.     

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.     

Variation among physical,chemical and technological properties in three Sicilian cultivars of Chickpea (Cicer arietinum L.)

Three Sicilian chickpea cultivars (‘Calia’, ‘Etna’ and ‘Principe’) were evaluated for physical, chemical and technological properties. Whereas no substantial differences were ascertained on seeds chemical composition, the cultivars greatly differed in terms of seed size, specific surface area (SSA) and seed coat incidence. These last two properties affected the technological properties of the seeds. In particular, a high SSA (‘Calia’) contributed to a faster softening, whilst a great coat thickness (‘Etna’) delayed both hydration and softening rate. The time required to obtain an acceptable firmness (cooking time) was greatly reduced by presoaking the seeds in salt solution (0.5% NaCl or NHCO₃). ‘Calia’ required the lowest cooking time when soaked in distilled water or in 0.5% NaCl. Presoaking seed in NaHCO₃ allowed halving the cooking time in all cultivars.     

Hard-to-cook defect in black beans: the contribution of proteins to salt soaking effects

Softening effects of chelating and ion-exchange agents in bean soaking solutions have been attributed to improved solubilization of pectates. The present results indicate a mechanism based on protein destabilization also contributes to softening. Solubility and calorimetric data established softening to be correlated with increased protein denaturation of isolated protein bodies and not with pectin solubilization during cooking, although pH 10, but not pH 7, carbonate buffer did extract significant (p ≤ 0·05) quantities of both pectin and protein. Carbonate ions reduced onset temperature of protein body denaturation by > 10°C. Rates of protein and pectin solubilization in hardened beans were faster then softening rates, suggesting that softening was not totally attributable to thermal degradation of macromolecular components or middle lamella dissolution.     

PECTIC SUBSTANCES AND FIRMNESS OF CUCUMBER PICKLES AS INFLUENCED BY CACL2, NACL AND BRINE STORAGE1

The effects of brine treatments (CaCl₂ and NaCl) and storage on pectic substances and texture of cucumber pickles were examined. Firmness of cucumber pickles was closely associated with the solubility characteristics and degree of esterification (DE) of pectic substances. Brining, storage, time of CaCl₂ addition and concentration of NaCl and CaCl₂ were all observed to influence the characteristics of pectic substances. Important to preventing softening was maintenance of pectic substances not extractable (NXP) by conventional methods, i.e., by water (WSP), the chelator sodium hex-ametaphosphate (CSP), and dilute alkali (OHSP). Erosion of NXP consistently resulted in increased levels of CSP and reduced firmness. Reducing the amount of demethylation of pectins was also associated with maintaining firmness. Although the DE declined rapidly during brining, tissues from treatments that enhanced firmness had pectic substances with the highest DE. CaCl₂ added to brine at the beginning of fermentation was most effective in preventing the demethylation of pectins and solubilization of NXP. In contrast, delayed addition of CaCl₂ and storage in low NaCl concentration (5% or less) caused greater pectin demethylation, erosion of NXP with concomitant increases in CSP and tissue softening.     

Relationships Between the Hard-to-Cook Phenomenon in Red Kidney Beans and Water Absorption, Puncture Force, Pectin, Phytic Acid, and Minerals

The effect of high temperature, high humidity storage on cooking quality and physicochemical properties of dry, mature red kidney beans was evaluated over a storage period of 9 months. The rate of softening of beans during cooking, and the rate of dissolution of pectin during cooking followed apparent first-order kinetics and their apparent rate constants correlated highly with each other. The apparent softening rate constants decreased with increasing time of storage. The loss of cookability in mature bean seeds stored under high temperature-high humidity conditions probably results from a decrease in phytic acid phosphorus and alterations in the ratio of monovalent to divalent cations in the tissue.     

Effects of Sodium Chloride Concentration on Firmness Retention of Cucumbers Fermented and Stored with Calcium Chloride

The firmness of cucumbers brined at 0.2% CaCl₂ was retained during fermentation (1 month) and storage (12 months) when 2.6, 4.2 or 5.8% NaCl also was present. Firmness retention was not improved (P≥0.05) during storage by increase in NaCl concentration to 11.9% after fermentation. In the absence of added NaCI, cucumbers were firm after fermentation, but firmness was reduced during storage to 69% of initial for whole cucumbers, 64% for mesocarp tissue, and 32% for endocarp tissue. Addition of uncharacterized softening enzymes. extracted from debris collected at a cucumber grading operation, resulted in softening of cucumbers brined at 1.8% NaCl in the absence of added CaC1₂. Addition of CaCl₂ reduced but did not eliminate softening by ths extract. Results indicated that the firmness of brined cucumbers could be retained at appreciably lower NaCl concentrations than those traditionally used but that the lower limit of NaCl required to prevent softening by possible contaminating enzymes is yet to be established.     

INFLUENCE OF SALTS AND pH ON THE FIRMNESS OF OLIVES IN ACID CONDITIONS

The effects of NaCl and CaCl₂ on the texture of olives, both treated and untreated with NaOH, at pH values lower than 4.0 were determined. Firmness of green olives declined as the pH decreased when calcium ions were not added. Calcium ions inhibited the softening rate of fresh and Spanish style green olives although this inhibitory effect depended on the pH. This firming action of calcium was higher at lower pH for fresh olives and at higher pH values for Spanish style green olives. The inhibitory effect of calcium on softening rate diminished as the concentration of cation increased. The presence of NaCl did not have any effect on the texture of either type of green olives. Lactic acid increased the softening rate of green olives by a higher proportion than acetic acid.     

Relationship Between Pectic Compositions and the Softening of the Texture of Japanese Radish Roots During Cooking

The pectins of Japanese radish roots were fractionated by successive extraction with three reagents: diluted HCI, sodium acetate buffer, and sodium hexametaphosphate solutions. The tissue, softened by thermal maceration, contained more HCl-soluble pectin (pA) than the sodium acetate buffer soluble pectin (pB). The degree of esterification (DE) of pA was higher than that of pB. With CaCI₂, pB formed some precipitates, but pA did not. The elution patterns of pA and pB by DEAE-cellulose column chromatography were different. A clear relationship between other dietary fiber (hemicellulose, cellulose and lignin) and softening of roots was not observed. The composition of pectins, especially DE, appeared to have an effect upon the texture of the Japanese radish softened during cooking.     

Influence of Pre-Soaking on Black Bean Cooking Kinetics

Soaking of black beans (Phaseolus vulgaris L.) and the subsequent effect on cooking kinetics was investigated. Unsoaked beans and beans soaked in water or a salt combination solution were water cooked at temperatures of 90–135°C. Bean softening did not follow first order kinetics. Using D_T values (defined as cooking times necessary to reach an “eating-soft” texture: Instron puncture force of 150g), softening activation energies (Ea's) for unsoaked, water, and salt combination soaked were 19.1, 31.3, and 38.9 Kcal/mole, respectively. Z values were calculated as 17, 22 and 36C°, respectively. These relationships suggest ways of safely reducing cooking time and energy expenditures.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings Affected by Calcium Chloride and Acetic Acid

Pepper rings packed in brine containing CaCl₂ were firmer, had higher bound calcium, chelator soluble pectin and pectin DE, and less water-soluble pectin (WSP) than peppers packed in brine containing no CaCl₂. Pepper rings packed in low acid brines (1% and 1.2% acetic acid) were firmer and had less WSP than those packed in high acid brine. Those samples (4% acetic acid) resulted in softening and pectin solubilization, but CaCl₂ resulted in less softening. Monosaccharide composition of cell walls was not affected by CaCl₂ or acetic acid. Firmness retention in CaCl₂ treated samples was probably due to greater association between calcium ions and pectic substances, which resisted acid hydrolysis.     

Variability in temperature distribution and cooking properties of ground pork patties containing different fat level and with/without salt cooked by microwave energy

This study was carried out to evaluate the cooking effects of fat level (10% and 20%) with and without NaCl (1.5%) on the microwave cooking pattern and properties of ground pork patties. Each patty was cooked from a thawed state to 76.7°C in a microwave oven with full power (900W). Cooking rate in patties produced without salt was not affected by fat level, but the addition of salt in pork patties decreased cooking rate, regardless of fat levels. The temperatures at the edges of the patties increased faster than those at the center or the mid-way positions. In the patties with NaCl, the temperature of the center position was higher than that of the mid-way position. Patties containing salt within the same fat level had higher moisture content and lower fat content than those without salt, although no significant differences in compositional properties were observed between the center, midway, or edge positions. Total cooking loss, drip loss, and reduction in diameter and thickness were higher in patties with 20% fat compared to those with 10% fat, but the addition of salt resulted in reduction, regardless of fat level. Also, the addition of salt increased the redness and reduced yellowness of the cooked products.     

Effect of processing on water absorption and softening kinetics in chickpea (Cicer arietinumL) seeds

The processing effect on the physical properties of chickpea seeds (kabuli type cv Athenas) is reported. Soaking of chickpea seeds in different solutions (distilled water, 0·5% NaHCO₃ and 0·5% CaCl₂) is characterised by a rapid water absorption followed by a decrease in the hydration rate to saturation point. An improvement in chickpea softening rate and water absorption during cooking, with previous 12 h soaking in 0·5% NaHCO₃, was observed. The presence of Ca²⁺ ions delayed the softening process in chickpea seeds. Physicochemical changes associated to the soaking and cooking process necessary for reducing cooking time are discussed. The texturometer method was estimated as a suitable objective method for the evaluation of the cooking degree in chickpea seeds. © 1998 Society of Chemical Industry     

Fermentation profiles of Manzanilla-Aloreña cracked green table olives in different chloride salt mixtures

NaCl plays an important role in table olive processing affecting the flavour and microbiological stability of the final product. However, consumers demand foods low in sodium, which makes necessary to decrease levels of this mineral in fruits. In this work, the effects of diverse mixtures of NaCl, CaCl₂ and KCl on the fermentation profiles of cracked directly brined Manzanilla-Aloreña olives, were studied by means of response surface methodology based in a simplex lattice mixture design with constrains. All salt combinations led to lactic acid processes. The growth of Enterobacteriaceae populations was always limited and partially inhibited by the presence of CaCl₂. Only time to reach half maximum populations and decline rates of yeasts, which were higher as concentrations of NaCl or KCl increased, were affected, and correspondingly modelled, as a function of salt mixtures. However, lactic acid bacteria growth parameters could not be related to initial environmental conditions. They had a longer lag phase, slower growth and higher population levels than yeasts. Overall, the presence of CaCl₂ led to a slower Enterobacteriaceae and lactic acid bacteria growth than the traditional NaCl brine but to higher yeast activity. The presence of CaCl₂ in the fermentation brines also led to higher water activity, lower pH and combined acidity as well as a faster acidification while NaCl and KCl had fairly similar behaviours. Apparently, NaCl may be substituted in diverse proportions with KCl or CaCl₂ without substantially disturbing water activity or the usual fermentation profiles while producing olives with lower salt content.     

OXIDATIVE STABILITY, COOKING YIELD AND TEXTURE OF PORK TREATED WITH A LOW-SODIUM SALT

The effect of a low-sodium salt mixture (LSSM) on the characteristics of cooked ground pork was investigated. LSSM, similar to NaCl, exhibited a minor but definite prooxidative effect in the system examined. The cooking yield of meat containing 1% LSSM was 69.8% compared to 74.3% for 1% NaCl. The cooking yields of samples with 2 and 3% LSSM were similar to those containing 2 and 3% of NaCl, respectively (p > 0.05). Maximum shear force values of samples containing 1% LSSM and 1% NaCl were similar. However, the maximum shear force values of meats treated with LSSM at 2 and 3% LSSM (19.1 and 24.8 kg) were lower (P < 0.05) than those containing 2 and 3% NaCl (21.9 and 27.0 kg). Addition of LSSM or NaCl to ground pork also enhanced the cooking yield and firmness over those containing no salt. The color characteristics of cooked pork remained generally unaffected by LSSM.     

Rheological and Gelation Properties of Meat Batters Prepared with Three Chloride Salts

The gelation and rheological properties of poultry meat emulsions prepared with three chloride salts (NaCl, KCl, MgCl₂) and 50/50 mixtures of the above salts at isoionic strength (IS = 0.42) were studied. The relationship between shear rate and shear stress for the different raw meat emulsions was found to be nonlinear and followed Bingham pseudoplastic behavior. The yield stress for the emulsion containing only MgCl₂ was significantly lower as compared to all the other treatments. The highest rigidity modulus values obtained during cooking were observed in the NaCl + MgCl₂ treatment followed by the NaCl + KCl, NaCl and KCl. The emulsion containing MgCl₂ only broke down at the initial stages of cooking, exhibiting the destabilizing effect of the magnesium cation.     

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.     

Relationship Between Degree of Pectin Methylation and Tissue Firmness of Cucumber Pickles

The relationship between pectin methylation and tissue firmness was examined in cucumber pickles exposed to pre-brining and brining treatments. Tissue treated with CaCl₂ prior to or during brining, blanched before brining or held at 2°C during brine storage resisted softening. Although all treatments reduced the degree of esterification (DE) of pectic substances, less demethylation occurred in treatments that protected against softening. Join point regression analysis of the data indicated that maximum firmness of mesocarp tissue was attained when the DE of pectins was 12.3 ± 1.2 or greater. Firmness declined concomitantly when the DE declined below 12.3 ± 1.2. Methods that protect against excessive demethylation of pectins appear to be important in retarding softening of cucumber pickle tissue during storage in brine.