DIELECTRIC PROPERTIES of STARCH SOLUTIONS AS INFLUENCED BY TEMPERATURE, CONCENTRATION, FREQUENCY and SALT

Dielectric properties of starch solutions (1 to 4% w/w) were evaluated at temperatures ranging from 20 to 80C at 10, 20 and 30 MHz. the effect of added salt (0.2 and 0.5% w/w) was investigated in relation to changes in trends exhibited by the relative permittivity, loss factor and penetration depth. the relative permittivity ranged from 46 to 308 and 65 to 92 for solutions with and without salt, respectively. the corresponding loss factor ranged 266 to 4133 and 9 to 266, respectively. Temperature, frequency, concentration and their interactions had different levels of significance on the dielectric properties of starch solutions. Salt enhanced the relative permittivity, and its effect conformed to the anomalous dispersion phenomenon. the loss factor increased with increasing temperature and salt content, and penetration depths associated with salt‐enriched samples were low compared to samples without salt. Generally, the effects of temperature, frequency, concentration and salt on the dielectric properties of starch solutions were attributed to the complex interaction between conductivity, density, moisture content, loss angle and starch rheological properties. Excellent correlations were developed that could be used for estimating the dielectric properties of starch solutions with and without salt.     

RESPONSE SURFACE MODEL FOR EFFECTS OF TEMPERATURE, WATER ACTIVITY AND pH ON GERMINATION OF BACILLUS CEREUS SPORES

A response surface model was developed for effects of temperature (20 to 40C), pH (4.5 to 6.5) and water activity (a_w) (0.94 to 0.99) on germination of Bacillus cereus ATCC 11778 spores. Germination depended, to varying extents, on the interactions among the independent variables and complexity of the medium. In particular it was affected (P < 0.05) by interactions of a_w with temperature and pH and by temperature in its quadratic term. The model was validated against data not used in its development. Mean absolute relative error of predictions (model accuracy) was 22.8% in model systems and 10.17% in real systems. Bias factors were 0.887 and 0.922 for model and real systems, respectively. Results indicated that the model developed was "fail safe" and provided reliable predictions of germination of B. cereus.     

Enzymatic Production,Bioactivity, and Bitterness of Chickpea (Cicer arietinum) Peptides

Chickpeas are inexpensive, protein rich (approximately 20% dry mass) pulses available worldwide whose consumption has been correlated with positive health outcomes. Dietary peptides are important molecules derived from dietary proteins, but a comprehensive analysis of the peptides that can be produced from chickpea proteins is missing in the literature. This review provides information from the past 20 years on the enzymatic production of peptides from chickpea proteins, the reported bioactivities of chickpea protein hydrolysates and peptides, and the potential bitterness of chickpea peptides in food products. Chickpea peptides have been enzymatically produced with pepsin, trypsin, chymotrypsin, alcalase, flavorzyme, and papain either alone or in combination, but the sequences of many of the peptides in chickpea protein hydrolysates remain unknown. In addition, a theoretical hydrolysis of chickpea legumin by stem bromelain and ficin was performed by the authors to highlight the potential use of these enzymes to produce bioactive chickpea peptides. Antioxidant activity, hypocholesterolemic, and angiotensin 1‐converting enzyme inhibition are the most studied bioactivities of chickpea protein hydrolysates and peptides, but anticarcinogenic, antimicrobial, and anti‐inflammatory effects have also been reported for chickpea protein hydrolysates and peptides. Chickpea bioactive peptides are not currently commercialized, but their bitterness could be a major impediment to their incorporation in food products. Use of flavorzyme in the production of chickpea protein hydrolysates has been proposed to decrease their bitterness. Future research should focus on the optimization of chickpea bioactive peptide enzymatic production, studying the bioactivity of chickpea peptides in humans, and systematically analyzing chickpea peptide bitterness.     

RESPONSE SURFACE METHODOLOGY STUDY ON THE POSSIBILITY OF NITRITE REDUCTION BY GLUCONO-δ-LACTONE AND ASCORBIC ACID IN TURKISH-TYPE FERMENTED SAUSAGE (SUCUK)

The primary goal of this study was to determine the residual nitrite-reducing effects of glucono-δ-lactone (GDL) and ascorbic acid (AA) in Turkish-type fermented sausage. Response surface methodology was used to investigate the simultaneous effects of processing variables, e.g., nitrite (0–200 mg/kg sausage), GDL (0–0.5% w/w) and AA (0–500 mg/kg sausage) on pH, moisture, residual nitrite, proteolysis, lipolysis, peroxide, yield and sensory score of the sausage. AA significantly ( P <  0.01) decreased the residual nitrite level; however, quadratic effect of AA showed an inverse effect. GDL did not produce the same effect on the residual nitrite level. The processing variables had no prominent effect on the proteolysis, lipolysis and peroxide. GDL and AA addition showed a negative effect on the yield and sensory scores of the sausages. The regression model predicted the optimum residual nitrite content to be 0.75 mg/kg. The critical values for nitrite, GDL and AA to obtain this optimum level were 147.56 mg/kg, 0.17% and 565 mg/kg, respectively.

PRACTICAL APPLICATIONS

Residual nitrite level is a major problem in the Turkish-type fermented sausage product with respect to some health concerns, residual nitrite causes a possible formation of the carcinogenic N -nitrosamines. The results of this study can be applied to reduce the residual nitrite level in sausage and to find the optimum levels of nitrite, glucono-δ-lactone and ascorbic acid levels to maintain the characteristic sausage quality properties. Based on the results, ascorbic acid can be used to reduce the residual nitrite levels in the sausage.     

Chemical,thermal and structural properties of alkaline-cooked (nixtamalised) chickpea (Cicer arietinum) flours

The present study examined how the alkaline cooking process affects the chemical, thermal and structural properties of the chickpea, evaluating different lime concentrations. Cooking was carried out at 94 °C, with two times of water for 15 min with five different lime concentrations. Regarding chemical composition, a decrease in protein and fat was observed: from 23.64% to a range of 18.26–19.93% for protein and from 8.20% to a range of 6.05–7.74% for fat. However, an increase was observed for ash and mineral content. The same pattern was observed for potassium. Raw chickpea did not present endotherm retrogradation, but a higher endotherm retrogradation was presented in chickpea cooked without lime, denoting that nixtamalisation decreased retrogradation. Additionally, V-amylose relative crystallinity increased with concentration of lime. Protein digestibility increases by β-sheet dismissing structure. Finally, it was observed that steeping time plays a key role in the nixtamalisation process.     

Extraction and characterization of chickpea (Cicer arietinum) albumin and globulin

ABSTRACT:  Albumin and globulin fractions of 1 Desi and 2 Kabuli varieties of chickpeas ( Cicer arietinum ) were extracted with water and salt solutions (K₂SO₄ and NaCl). The extractable yields and particularly the albumin-globulin ratio varied greatly with the extraction medium and chickpea variety. Depending on the procedure employed, albumin could be extracted as a major fraction of chickpea proteins. Higher levels of essential amino acids and sulfur containing amino acids were found in albumins than in globulins of all chickpeas investigated. The common structural characteristics of both Kabuli and Desi chickpea albumins and globulins were clearly identified by densitometric profiles of their sodium dodecyl sulfate polyacrylamide gel patterns. Albumins contained subunits with higher molecular weights than those of globulins. The in vitro digestibility of the chickpea proteins by papain, pepsin, chymotrypsin, and trypsin indicated that globulins were more susceptible to proteolytic hydrolysis.     

Antioxidant properties of sand roasted and steam cooked Bengal gram (Cicer arietinum)

Nine different Bengal gram (Cicer arietinum) cultivars were subjected to sand roasting and steam cooking and the effect on antioxidant properties were evaluated. The control untreated Bengal gram cultivars varied significantly with respect to their antioxidant properties. Both the thermal treatments lead to a significant increase in total phenolic content of up to 54% upon roasting and 97% upon steam cooking, respectively. Similarly, a significant increase in antioxidant activity was also observed by roasting (up to 64.5%) and steam cooking (up to 225%). A significant decrease in total color difference was noticed upon roasting (up to 11%) and steam cooking (up to 21%). The reducing power was increased significantly after roasting and steam cooking, however, steam cooking brought about greater increase in reducing power (up to 109%). Metal chelating activity was increased by up to 91.5% upon roasting and steam cooking. The study revealed that the steam cooking brought about greater increase in total phenolic content, reducing power, and metal chelating activity as compared to roasting.

     

Inhibitor activities of chickpeas (Cicer arietinum L) against bovine,pocine and human trypsin and chymotrypsin

Twenty-two chickpea samples (7 genotypes, 4 desi and 3 kabuli) representing three different sites of cultivation and three years of harvest were examined for their inhibitory activities against bovine, porcine and human trypsin/chymotrypsin, and compared for their isoinhibitor patterns. No significant difference in inhibitor activity between the desi and kabuli seed types was found for any of the enzymes used, when data from different locations and years were averaged. However, some significant differences were observed between individual cultivars when compared at the same location and in the same year. Inhibitor activities against the three trypsins and three chymotrypsins were statistically different with activities against bovine (5.46 ± 1.21) > porcine (5.24 ± 1.18) > human (4.45 ± 0.93) trypsin and those against bovine (4.89 ± 1.27) < porcine (8.91 ± 2.14) < human (10.54 ± 2.50) chymotrypsin (means ± standard deviation, expressed as mg active enzyme completely inhibited per g seed meal). Levels of activity of both trypsin and chymotrypsin inhibitor were influenced by the location and year of cultivation. Isoelectric focusing yielded identical inhibitor patterns for all samples, indicating seven isoinhibitors acting against trypsin and chymotrypsin. Results are discussed in relation to nutritional significance of these inhibitors and perspectives for breeding genotypes low in protcase inhibitors.     

Effects of gamma irradiation on physical and chemical properties of chickpeas (Cicer arietinum)

Changes in the physical and chemical properties of chickpeas gamma irradiated with ⁶⁰Co at doses of 0–50 kGy were investigated. Irradiation between 0 and 20 kGy had no significant effect on the hydration capacity of the chickpeas; however, increasing the dose from 20 to 50 kGy significantly decreased the hydration capacity owing to leaching of soluble compounds from the cotyledon to the water. There was an improvement in cooking quality (defined as degree of softness) with increased irradiation. Gelatinisation properties of the starch (measured with a Rapid Visco‐Analyser) exhibited a deterioration with increasing irradiation dose, while reversed phase HPLC identified a sequential decrease in low‐molecular‐weight protein composition with increasing irradiation dose. © 2002 Society of Chemical Industry     

Characterisation and functional properties of proteins of some Indian chickpea (Cicer arietinum) cultivars

BACKGROUND: Chickpea (Cicer arietinum L.) proteins have received attention during recent years owing to their higher biological values and better functional ingredients than oilseed proteins. In this study the composition, fractionation, electrophoretic behaviour and functional properties of five chickpea protein concentrates were determined. RESULTS: The chickpea proteins contained 15.9–54.8 g kg^?1 albumin, 48.9–154.1 g kg^?1 globulin, 39.2–76.5 g kg^?1 glutelin and traces of prolamin. Electrophoresis of the various fractions revealed that albumin and globulin were made up of sub‐units of different molecular weights ranging from 7 to 96 kDa. Water and oil absorption of the protein concentrates varied from 1.15 to 2.75 g g^?1 and from 2.60 to 5.65 g g^?1 respectively. Foaming capacity and foam stability of the protein concentrates were good and improved with the addition of salt (10 g L^?1 NaCl) or sugar (100 g L^?1 sucrose) at both isoelectric and neutral pH. Emulsifying capacity and emulsion stability of the protein concentrates were good and excellent respectively. CONCLUSION: Protein concentrates prepared from chickpeas have potential use in food formulations owing to their good emulsifying/foaming and water/oil‐binding capacities. Copyright © 2008 Society of Chemical Industry     

RESPONSE SURFACE MODELS FOR THE EFFECTS OF TEMPERATURE,pH, SODIUM CHLORIDE,AND SODIUM NITRITE ON THE AEROBIC AND ANAEROBIC GROWTH OF STAPHYLOCOCCUS AUREUS 196E1

The effects and interactions of temperature (12–45C), initial pH (4.5–9.0), NaCl (0.5–16.5%), and sodium nitrite (1–200 μg/ml) on the aerobic and anaerobic growth of Staphylococcus aureus 196E were studied using 50 ml portions of Brain Heart Infusion Broth in 250ml unsealed and sealed trypsinizing flasks, respectively. The flasks were inoculated to a level of approximately 10³ cfu/ml, incubated on a rotary shaker, sampled periodically, and enumerated on Tryptic Soy Agar. Growth curves were generated by fitting the data to the Gompertz function using nonlinear regression analysis. The general growth characteristics of S. aureus in response to the five environmental variables were similar to those observed by other investigators including (1) enhanced growth in the presence of oxygen, (3) ability to grow at high sodium chloride concentrations, and (3) dependence of the bacteriostatic activity of sodium nitrite on pH and oxygen availability. Supplemental studies indicated that growth kinetics were independent of inoculum size, which allowed the Gompertz A term to be treated as a constant. However, the maximum population density (MPD) achieved by the cultures was dependent on the independent variables, requiring that it be modeled in addition to the Gompertz B and M terms. The MPD was then used to calculate the Gompertz C term. Quadratic and cubic response surface models were generated using various data transformations. Quadratic models using and LN-transformation provided reasonable predictions of the effects of the four variables on the growth kinetics of S. aureus, and should prove useful for providing initial estimates of the behavior of S. aureus in foods.     

ELECTRICAL CONDUCTIVITY of SELECTED JUICES: INFLUENCES of TEMPERATURE,SOLIDS CONTENT,APPLIED VOLTAGE,and PARTICLE SIZE1

A device was developed to determine the electrical conductivities of foods under ohmic or conventional heating conditions. Orange and tomato juices (serum and various solids contents) were tested in the device. the electrical conductivity of juices increased with temperature and decreased with solids content. the temperature dependence of conductivity was linear, both under conventional and ohmic heating. Experiments on suspensions of carrot juice solids, and polystyrene spheres in sodium phosphate solution showed an increase in electrical conductivity of the suspension with decreasing particle size.     

Cooking quality and nutritional attributes of some nely developed cultivars of chickpea (Cicer arietinum)

Eight nely developed and to commonly gron chickpea (Cicer arietinum L) cultivars ere evaluated for their cooking quality by measuring cooking time, ater absorption and sensory properties. Nutritional aspects of cooked hole seed samples ere measured chemically (including amino acids and minerals) and biologically in nitrogen-balance experiments ith rats. Results indicated that kabuli (cream seed coat) may be generally preferred to desi (bron seed coat) cultivars in terms of cooking time and sensory properties. Calcium content as noticeably higher in desi than in kabuli cultivars, hereas magnesium, iron, copper and zinc shoed no definite trend. Levels of lysine, threonine, methionine and cystine of these genotypes ere ithin the range of FAO values. Desi and kabuli revealed no noticeable difference in protein and amino acids. Hoever, biological value as considerably higher for kabuli than for desi. Consequently, kabuli contained more utilisable protein and may be nutritionally better than desi. In general, cooking quality and nutritional aspects of both nely developed and control cultivars ere similar.     

Determination of Polyphenols,Flavonoids, and Antioxidant Capacity in Colored Chickpea (Cicer arietinum L.)

ABSTRACT: Dry legumes are staple and potentially functional food, being a good source of polyphenols, flavonoids, and antioxidant activity. The objective of this study was to determine the total polyphenol content (TPC), total flavonoid content (TFC), and their relation with antioxidant capacity in 17 chickpea lines having colored seed coats (black, red, brown, green, rubiginous, gray, yellow, cream, or beige). The seed coat usually contains more than 95% of these compounds. In this study, both TPC and TFC varied significantly among different lines and were highly correlated to antioxidant activity. Colored seeds contained up to 13-, 11-, and 31-fold more TPC, TFC, and antioxidant activity, respectively, than cream- and beige-color seeds. Thus, colored chickpea could be a potentially functional food in addition to its traditional role of providing dietary proteins and dietary fibers.     

Effects of processing and cooking on ascorbic acid content of chickpea (Cicer arietinum L) varieties

Chickpea (Cicer arietinum L) is an important source of protein in several developing countries. Two commonly grown chickpea cultivars, HPG‐17 and C‐235, were evaluated for their physicochemical characteristics such as 100‐seed weight and density. Both chickpea varieties were subjected to various processing treatments and then analysed for their ascorbic acid content. The ascorbic acid content was generally found to be higher in the C‐235 variety, but it was higher in the HPG‐17 variety after germination. Significant results were obtained for both varieties after various treatments such as pressure cooking, germination, parching and solar cooking. It was found that the ascorbic acid content in both varieties decreased after all treatments except germination. © 2001 Society of Chemical Industry