Improving textural quality in frozen jalapeño pepper by low temperature blanching in calcium chloride solution

The effects of low temperature blanching in calcium chloride solution of jalapeño peppers prior to freezing, on firmness retention, pH, methanol, colour and calcium ions of the product, were evaluated by response surface methodology. Texture, methanol content and pH were affected by all of the variables studied (P = 0.05). The optimum response was obtained at temperatures of 63.3–66 °C, calcium chloride concentrations of 0.17–0.21 m , immersion time of 11.6–14.4 min, with a holding time after blanching of 56.6–66.1 min. Microscopic evaluation of the thawed pepper showed that blanching in CaCl₂ solution provided a protective effect in maintaining cell wall integrity.     

Thermal and Calcium Pretreatment Affects Texture, Pectinesterase and Pectic Substances of Frozen Sweet Cherries

Freezing causes loss of turgidity and firmness in sweet cherries. Thermal pretreatment at 50°C for 10 min followed by immersion in 100 mM CaCl₂ and thermal pretreatment at 70°C/2 min with or without immersion in 100 mM CaCl₂ prevented freezing-induced loss of firmness. Thermal pretreatments increased the pectin fraction soluble in EDTA, reduced the degree of pectin esterification, and increased both the concentration of divalent cations in the cell wall and the pectinesterase activity bounded to the cell wall. Immersion in CaCl₂ increased the concentration of Ca²⁺ cations in the cell wall and enhanced the effect of thermal pretreatments on pectinesterase activity.     

Culture Filtrates from a Fermented Rice Product (Lao-Chao) and Their Effects on Milk Curd Firmness

To develop a new Oriental-style dairy product, the characteristics of culture filtrate from lao-chao with Rhizopus oryzae, used as a milk-clotting agent, and factors (heat-treatments, calcium, sucrose, and curdling temperature) affecting curd firmness were determined. The optimal conditions for proteolytic activity were around 40°C and pH 3. No activity was detected over the range of pH 8 to 11. After high-heat treatment (121°C, 15 min) on skim milk, no clotting was observed. Sucrose resulted in the retardation of milk-clotting. Ca⁺⁺ could be used to increase curd firmness which also increased from 29. 2–2.8g to 80. 3–4.7g when the curdling temperature was increased from 25°C to 45°C.     

Effect of calcium on the storage life of oro (Antiaris africana)

The effects of calcium on the ascorbic acid, chlorophyll, titratable acidity and texture (firmness) of stored oro (Antiaris africana (Mill)) friuits (average weight 100 g ) were studied. Three groups of the fruits were dipped in 20 g litre^?1, 40 g litre^?1 CaCl₂ solutions and deionised water respectively for I0 min. The fourth group, which was untreated, served as the control and was also packaged in heat-sealed cellophane bags. The fruits were displaced and stored at ambient temperature (28 ± 2°C). The calciumtreated fruits which kept better were firmer and had a slight colour change (chlorophyll) which also produced a progressive increase in ascorbic acid level during storage. The titratable acidity of the fruits did not fluctuate as signijcantly as that of the untreated (control) fruits.     

Factors influencing the gelation and rennetability of camel milk using camel chymosin

The effects of temperature, pH, concentration of camel chymosin and addition of CaCl₂ on the hydrolysis of κ-casein (κ−CN) and the coagulation kinetics of camel milk were investigated. The rate of κ−CN hydrolysis was higher at 40 °C than at 30 °C and with increasing addition of chymosin and decreasing pH. For all samples gelation was initiated at levels of camel milk κ−CN hydrolysis >95%. The gelation time (T_g) of camel milk was significantly reduced (from 717 to 526 s) at 30 °C when the concentration of chymosin was increased, but was independent of chymosin concentration at 40 °C. Reducing pH also reduced T_g. The gel firmness increased at 40 °C (58 Pa) compared with 30 °C (44 Pa) and effect of CaCl₂ addition on the gelation properties of camel milk was found to be dependent on pH; a significant improvement was only found at pH 6.3.     

Canning Quality Evaluation of Pinto and Navy Beans

Thermal processing of pinto and navy beans at 121.1°C for 16 or 14 min in a still retort gave similar sterilization value (F_o= 10) as the processing at 115.6°C for 45 min. The 121.1°C/16 or 14 min process produced beans with greater firmness than the 115.6°C/45 min process. The addition of CaCl₂ and EDTA improved firmness and color of canned beans. Calcium chloride also reduced clumping and splitting of the canned beans. Sensory evaluation showed that the acceptability of canned beans was reduced when CaCl₂ was increased up to 10 mM. High correlation between firmness and soluble pectin in various bean cultivars implied that soluble pectin content could be used as a parameter for screening bean cultivars with desirable firmness.     

Influence of sucrose on cold gelation of heat‐denatured whey protein isolate

A solution of heat‐denatured whey proteins was prepared by heating 100 g kg⁻¹ whey protein isolate (WPI) at pH 7.0 to 75 °C for 15 min in the absence of salt. Heat treatment caused the globular protein molecules to unfold, but electrostatic repulsion opposed strong protein–protein aggregation and so prevented gel formation. When the heat‐denatured whey protein solution was cooled to room temperature and mixed with 15 mM CaCl₂, it formed a gel. We investigated the influence of the presence of sucrose in the protein solutions prior to CaCl₂ addition on the gelation rate. At relatively low concentrations (0–100 g kg⁻¹), sucrose decreased the gelation rate, presumably because sucrose increased the aqueous phase viscosity. At higher concentrations (100–300 g kg⁻¹), sucrose decreased the gelation rate, probably because sugar competes for the water of hydration and therefore increases the attraction between proteins. These data have important implications for the application of cold‐setting WPI ingredients in sweetened food products such as desserts. © 2000 Society of Chemical Industry     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings as Affected by Preheating and Storage

Changes in cell wall pectic substances, degree of pectin methylation, bound calcium and firmness were determined in preheated and nonpreheated fresh pack jalapeño pepper rings stored for 5 mo. Pepper rings preheated for 60 min at 50°C in a brine solution (8% NaCl and 0.2% CaCl₂, were firmer, had more nonextrctable pectins (NXP), more bound calcium, less water-soluble and chelator-soluble pectins (CSP), and less pectin methylation than nonpreheated pepper rings. The greater formation and maintenance of nonextractable pectins, which resisted acid hydrolysis during pasteurization and storage is probably an important factor in firming.     

Fermentation of Cucumbers Brined with Calcium Chloride Instead of Sodium Chloride

ABSTRACT: Waste water containing high levels of NaCl from cucumber fermentation tank yards is a continuing problem for the pickled vegetable industry. A major reduction in waste salt could be achieved if NaCl were eliminated from the cucumber fermentation process. The objectives of this project were to ferment cucumbers in brine containing CaCl₂ as the only salt, to determine the course of fermentation metabolism in the absence of NaCl, and to compare firmness retention of cucumbers fermented in CaCl₂ brine during subsequent storage compared to cucumbers fermented in brines containing both NaCl and CaCl₂ at concentrations typically used in commercial fermentations. The major metabolite changes during fermentation without NaCl were conversion of sugars in the fresh cucumbers primarily to lactic acid which caused pH to decrease to less than 3.5. This is the same pattern that occurs when cucumbers are fermented with NaCl as the major brining salt. Lactic acid concentration and pH were stable during storage and there was no detectable production of propionic acid or butyric acid that would indicate growth of spoilage bacteria. Firmness retention in cucumbers fermented with 100 to 300 mM CaCl₂ during storage at a high temperature (45 °C) was not significantly different from that obtained in fermented cucumbers with 1.03 M NaCl and 40 mM CaCl₂. In closed jars, cucumber fermentations with and without NaCl in the fermentation brine were similar both in the chemical changes caused by the fermentative microorganisms and in the retention of firmness in the fermented cucumbers.     

Preparation and Partial Characterization of Eggshell Calcium Chloride

To minimize eggshell waste, calcium in eggshells was extracted as calcium chloride using 4% (w/v) HCl solution for an extraction period of 3 hs with the ratio of eggshell to HCl being 1:15 (w/v). After hydrolysis, the residues were removed by centrifugation at 1774 × g for 10 min, and the solution was heated to 110–115°C until dried, this gave an eggshell calcium chloride at a yield of 87.38% (w/w). The calcium chloride powder in this study was composed of 0.3% protein and 94.37% ash, with pH 5.27 and showed high solubility. It contained minute amount of heavy metal constituents within the specification of the Thai Food Act. X-ray diffraction analysis indicated that eggshell calcium chloride powder thus prepared was composed mainly of CaCl₂.2H₂O. The eggshell CaCl₂ was also tested for its functional property as a firming agent in canned rambutan. The results showed that both eggshell and commercial calcium chloride gave a firm texture to canned rambutan, therefore eggshell CaCl₂ can be prepared and used as food processing aids.     

Effect of pretreatments and drying temperatures on sweet potato flour

Effect of pretreatments with 1 w/v% sodium hydrogen sulphite (NaHSO₃) and 1 w/v% calcium chloride (CaCl₂) and drying temperatures (55, 60 and 65 °C) on sweet potato flour were investigated. Flour treated with CaCl₂ had higher amounts of ascorbic acid and β‐carotene (10.61–12.54 and 3.26–3.46 mg 100 g^?1 wet basis, respectively) than that treated with NaHSO₃ (9.47–11.47 and 3.05–3.43 mg 100 g^?1 wet basis, respectively). Total phenolic content and water absorption index (wet basis) were highest at 65 °C when treated with NaHSO₃ (10.44 mg 100 g^?1 and 2.49 g g^?1 respectively) and CaCl₂ (9.52 mg 100 g^?1 and 2.85 g g^?1 respectively). Swelling capacity (wet basis) was highest at 60 °C when treated with CaCl₂ (2.96 g g^?1) whereas when treated with NaHSO₃ (2.85 g g^?1) it was highest at 55 °C. Freeze‐dried samples treated with NaHSO₃ had higher lightness and total phenolic content while CaCl₂‐treated samples had higher β‐carotene and ascorbic acid. The results showed that good quality flour could be produced after soaking in CaCl₂ and dried at 65 °C.     

High Hydrostatic Pressure as a Hurdle for Zygosaccharomyces bailii Inactivation

The combined effects of high hydrostatic pressure (HHP, 172, 345, 517 or 689 MPa), duration of HHP treatment (0, 2, 4, or 10 min), water activity (a_w 0.98 or 0.95), and potassium sorbate (PS) concentration (0 or 1000 ppm) on Zygosaccharomyces bailii inactivation were evaluated at pH 3.5 and 21°C in laboratory model systems. Inactivation of the initial inoculum (? 1.0 times; 10⁵ CFU/mL) occurred when the pressure was 689 MPa regardless of a_w PS or duration of treatment. Lower pressure was required for Z. bailii inactivation in the presence of PS.     

Calcium Treatments Affect Storage Quality of Shredded Carrots

Carrot shreds, sticks and slices were dipped in solutions of CaCl₂ alone, or with chlorine and stored at 0, 5 or 10°C to determine the effects of calcium (Ca) on storage quality. A 0.5% or 1% CaCl₂ treatment maintained firmness and reduced microbial growth of carrot shreds at all temperatures. These treatments also resulted in lower tissue pH than in the water-dipped controls. Treatments increased Ca content slightly in sticks and slices and substantially in shreds and had no effect on storage quality of sticks or slices.     

Influence of NaCl and CaCl2 on Cold-Set Gelation of Heat-denatured Whey Protein

Heat‐denatured whey‐protein isolate (HD‐WPI) solutions were prepared by heating a 10 wt% WPI solution (pH 7) to 80 °C for 10 min and then cooling it back to 30 °C. Cold‐set gelation was initiated by adding either NaCl (0 to 400 mM) or CaCl₂ (0 to 15 mM). Both salts increased the turbidity and rigidity of the HD‐WPI solutions. Gelation rate and final gel strength increased with salt concentration and were greater for CaCl₂ than NaCl at the same concentration because the former is more effective at screening electrostatic interactions and can form salt bridges.     

Biotechnological potential of industrial wastes for economical citric acid bioproduction by Aspergillus niger through submerged fermentation

Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL‐567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25–35 °C), pH (3–5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34 g L^?1 CA was recorded using BSL at pH 3.5 and temperature 30 °C after 120‐h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34 g L^?1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30 g L^?1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation.     

Effect of Vacuum Impregnation Combined with Calcium Lactate on the Firmness and Polysaccharide Morphology of Kyoho Grapes (<Emphasis Type="Italic">Vitis vinifera</Emphasis> x <Emphasis Type="Italic">V. labrusca</Emphasis>)

The effects of vacuum impregnation (VI) with 2% calcium lactate treatment on the VI properties (obtained from hydrodynamic mechanism and deformation–relaxation phenomena models), firmness, and pectin of Kyoho grapes were investigated. Fruit pectin was analysed by atomic force microscopy (AFM). VI was applied for 10–35 min at 25–45 °C and 5 kPa. The maximum values of effective porosity, ε_e (0.606%), and volume fraction, X (0.588%), occurred at 35 °C when the VI time was 15 min. No change was observed in the volumetric deformation (γ ≈ 0) of the grapes after the impregnation. The firmness significantly increased at 35 °C VI (from 12.93 to 14.47 N). According to the AFM results, calcium mainly inhibited the degradation of chelate-soluble pectin and sodium carbonate-soluble pectin short branches during the VI. Under the studied conditions, the validity of VI to incorporate calcium into fruit to improve the quality of grapes was verified, and a final corresponding product was obtained by VI.     

Production of feed enzymes from citrus processing waste by solid‐state fermentation with Eupenicillium javanicum

Bingtang sweet orange processing waste was utilised to produce four feed enzymes (Endoglucanase, β‐glucosidase, pectinase and xylanase) by the solid‐state fermentation (SSF) with Eupenicillium javanicum. The factors related with SSF including moisture content, temperature, initial pH, time, carbon source (0.5 g), nitrogen sources (0.05 g), inorganic mineral salts (0.1 g) were investigated separately. The corresponding optimal condition was: moisture content 80% (w/w), temperature 30 °C, natural pH, time 96 h, wheat bran 0.5 g, (NH₄)₂SO₄ 0.05 g or NaNO₃ 0.05 g, CaCl₂ 0.1 g. The L₉(3⁴) orthogonal experiment results showed that the optimal condition for producing above multiple enzymes was: moisture content 80% (w/w), temperature 30 °C, wheat bran 1 g, (NH₄)₂SO₄ 0.05 g, NaNO₃ 0.05 g, CaCl₂ 0.1 g, fermentation time 96 h and natural pH. Under this condition, the average activity of Endoglucanase (CMCase), β‐glucosidase, pectinase and xylanase by E. javanicum could reach 46.80, 49.64, 51.87 and 106.42 U g^?1, respectively, which was significantly higher than those in single factor experiments. Our present results demonstrated that E. javanicum could also be an effective and useful fungus for multienzyme preparation especially for β‐glucosidase and xylanase from citrus processing wastes.     

Effect of pH on Enzyme Inactivation Kinetics in High-Pressure Processed Pineapple (Ananas comosus L.) Puree Using Response Surface Methodology

Effect of pH and high-pressure process treatments viz. pressure, temperature, and dwell time on inactivation of polyphenoloxidase (PPO), peroxidase (POD), bromelain (BRM), and pectinmethylesterase (PME) in pineapple puree was studied. Experiments were conducted according to rotatable central composite design (RCCD) within the range (?α to?+?α) of 100–600 MPa, 20–70 °C, and 0–30 min at three different pH levels (3.0, 3.5, and 4.0) followed by analysis through response surface methodology (RSM). Enzyme inactivation was significantly (p?k in min^?1) revealed that PPO was the most resistive (k ranged between 0.0020 and 0.0379 min^?1) when compared with other three enzymes within the experimental domain. Increased k at lower pH with constant pressure and temperature depicted that pH had negative effect on the inactivation process. The optimized conditions targeting maximum inactivation of PPO, POD and PME with simultaneous retention of BRM in pineapple puree, were 600 MPa/60 °C/9 min, 600 MPa/60 °C/10 min and 600 MPa/60 °C/10 min for the samples of pH 3.0, 3.5, and 4.0, respectively.     

Supercritical CO2 Extraction of Oil from Atlantic Mackerel (Scomber scombrus) and Protein Functionality

Supercritical carbon dioxide (SC-CO₂) extraction temperature and pressure for oil removal from freeze-dried, fall Atlantic mackerel muscle were optimized. The effect of extraction conditions on pH and water-binding potential (WBP) of the protein residue was evaluated. For the temperature range (35–55°C) and pressure interval (20.7–34.5 MPa), 34.5 MPa/35°C gave highest oil yield and concentration of ω-3 fatty acids. SC-CO₂ extraction at higher pressure levels caused slight decreases in protein residue pH. WBP of residual proteins was maximal at 1.49g H₂O/g protein for 34.5 MPa/45°C. The high lipid removal and retention of protein functionality in the residue after oil extraction may make such processes useful for future food applications.     

Short communication: Calcium partitioning during microfiltration of milk and its influence on rennet coagulation time

Pasteurized skim milk was subjected to (1) microfiltration (MF) at 50°C and (2) MF at 6°C after storage at 2°C. The products of these treatments were retentate (RMF50) and permeate (PMF50), and retentate (RMF6) and permeate (PMF6), respectively. Additionally, RMF50 was subjected to (3) cold MF after water dilution to produce retentate (RMF6R) and permeate (PMF6R). Calcium migration was monitored by analyzing ionic, soluble, and total calcium content in feed, retentates, and permeates. The influence of calcium partitioning and calcium addition to feed, retentates, and retentates diluted with water was determined. Without CaCl₂ addition, only skim milk, RMF50, and RMF6 coagulated after rennet addition. Higher true protein and casein content of RMF50 and RMF6 resulted in shorter time of renneting. The retentates diluted with water showed no signs of coagulation within 40 min. The addition of PMF6R to RMF50 did not affect rennet coagulation time within the observed 40 min in comparison to RMF50 + water. In general, higher CaCl₂ addition resulted in shorter rennet coagulation time. Special attention should be paid to calcium partitioning during membrane processing of cheesemilk. The level of calcium addition should be adopted to calcium content in such cheesemilk, which is affected by conditions of the filtration process (i.e., concentration factor and temperature).