Preparation and characterisation of the C10 to C18 even-numbered triethanolamine alkyl sulphates

The preparation and characterisation of purified C₁₀ to C₁₈ even-numbered triethano-lamine alkyl sulphates are described. Critical micelle concentrations were determined at 25°C, using both conductance and drop volume methods. The authenticity and purity of the products are established, and evidence presented for amending the accepted melting points for two of the compounds.
Preparation et identification des alkysulfates de triethanolamine en C₁₀, C₁₂, C₁₄, C₁₆, C₁₈     

PRODUCTION OF CO2 AND C2H4 AFTER GAMMA IRRADIATION OF STRAWBERRY FRUIT

Strawberry fruit (Fragaria ananassa, Duch. cv ‘Kent’) were irradiated at doses from 0 to 4 kGy and stored at 10°C to verify whether irradiation at very low doses could delay postharvest ripening while causing minimal damage to the tissues. CO₂ and C₂H₄ production were used as stress indicator. Anthocyanins and titratable acidity were measured as maturity parameters. CO₂ and C₂H₄ production increased six hours after irradiation. The increase in CO₂ production was proportional to the dose of irradiation and was highest at 4 kGy. Maximum C₂H₄ production was reached at 1 kGy. The different response of CO₂ and C₂H₄ production to irradiation suggests that the membrane system supporting C₂H₄ production was more sensitive to gamma rays than mitochondrial CO₂ production. Irradiation at 0.3 kGy slightly delayed color development in the fruit. Overall, the results indicated that it may be possible to use irradiation at a low dose to delay ripening while causing only minimal tissue damage.     

Oxidation of Tryptophan by H2O2 in Model Systems

Degradation reactions of tryptophan (trp) and the dipeptides alanyltryptophan (ala-trp) and phenylalanyltryptophan (phe-trp), induced by H₂O₂, were investigated under different conditions in aqueous systems. Decreases in the content of trp as well as the formation of soluble degradation products were determined. Highest losses of trp were obtained after H₂O₂ treatment at 100°C for 2 hr at pH 8.5. Lowest losses occurred at pH 4.0, 25°C, for 30 min. The destruction of trp in ala-trp was similar, while losses of trp in phe-trp under the same reaction conditions were lower. This was indicative of a negative induction effect of the phenyl ring. The quantity of degradation products showed extensive variations, dependent upon the radical mechanism of the oxidation reaction.     

Dynamic Changes of Headspace Gases in CO2 and N2 Packaged Fresh Beef

Two independent experiments were conducted to examine the effects of initial packaging/product conditions and storage conditions on in-package headspace pressure changes for modified atmosphere packaged beef during 12 hr storage. Headspace-to-meat volume ratio 1.8 to 5.9, surface area 200--800 cm², sample volume 0.22–0.75L, storage at 3–13°C and initial gas composition 20–100% CO₂ balanced with N₂ were studied. Headspace-to-meat volume ratio was the most important packaging parameter, but surface area and meat volume also affected headspace CO₂ changes. Decreased storage temperature reduced CO₂ concentration remaining in headspace. Higher initial CO₂ concentration resulted in greater concentration changes.     

Staphylococcus aureus Growth and Enterotoxin Production in Mushrooms

An enterotoxin A (SEA) producing strain of Staphylococcus aureus was inoculated onto mushrooms and incubated under simulated pre-and post-canning conditions. S. aureus grew and produced SEA in mushrooms incubated at 25°C in 10% to 20% NaCl. Growth and SEA production occurred when mushrooms were stored in plastic bags at 37°C, but not at 25°C. Mushrooms heat-processed at 121.1°C supported S. aureus growth and SEA production. No SEA was recovered from mushrooms inoculated with 1 or 10 ng SEA/g and heated at 121.1°C for 4.5 min. At higher inoculated SEA levels (100 and 1,000 ng/g), SEA was detectable after 10 min of heating. Staphylococcal enterotoxin could be present in canned mushrooms as a result of pre-, but more likely post-processing contamination.     

Characterisation of soybean glycinin and β-conglycinin fractionated by using MgCl2 instead of CaCl2

A simple two step precipitation method was used to investigate the effect of MgCl₂ instead of CaCl₂ on fractionation of soybean glycinin and β-conglycinin. Compositional and physicochemical properties of the resulting protein fractions were characterised. The optimised procedure, in terms of protein yield, purity, phytate content and physicochemical properties, was obtained when the addition of 5 m m MgCl₂ was used. After application of 5 m m MgCl₂, the phytate content of the glycinin-rich and β-conglycinin-rich fractions was about 0.4% and 1.3%, respectively, but the addition of 5 m m CaCl₂ increased the phytate content of the glycinin-rich fraction to 1.25% and decreased that of β-conglycinin-rich fraction to 0.67%. Low phytate protein product was suitable for use in infant formula and acidic food. The solubility of the glycinin-rich fractions with MgCl₂ was significantly higher than that with CaCl₂ at pH < 4.5. Application of MgCl₂ improved thermal stability of the β-conglycinin-rich fraction.     

SPECIFICITY OF THE FERRIC-H2SO4 REAGENT FOR ALGINATES

SUMMARY— Alginate in foods was isolated from papain digests of the samples as the insoluble calcium salt. dispersed by sodium hexametaphosphate and a 1- to 5-ml aliquot of the dispersion 50–250 μg of sodium alginate) dried at 100°C. Heating of the anhydrous sample in the presence of the ferric-H₂SO₄ reagent for 12 min at 60°C produced a pink color with maximum absorption at 490–515 mμ and maximum density after aging for 90 min at 29±1°C. Under these conditions, proteins, amino acids (except tryptophane), other carbohydrates, vitamins. food additives and incipients did not interfere. The presence of water in the medium rendered the reaction nonspecific and increasing the temperature above 60°C or heating for longer periods at lower temperatures resulted in color formation by other polyuronides, especially pectin and pectic acid. Recoveries of alginate from several products were good: Milk, 94–98%; ice cream, 93.5–98%; pasteurized process cheese spread. 92.6-95%; chocolate milk, 92.4-95%; dietetic foods, 90-97.2%.     

Postharvest CO2 and Ethylene Production and Quality Maintenance of Fresh-Cut Kiwifruit Slices

The quality attributes and gas production of fresh-cut kiwifruit slices (Actinidia deliciosa cv. Hayward) were studied to identify the optimum ranges of storage temperature, relative humidity, and atmospheric composition. Also the effects of wounding, C₂H₄ addition or removal, and chemical treatments (calcium, ascorbic acid, citric acid) on deterioration rate were investigated. Flesh softening was the major quality loss of stored fresh-cut kiwifruit slices. Fresh-cut kiwifruit slices had a shelf-life of 9–12 days if treated with 1% CaCl₂ or 2% Ca lactate, and stored atO-2°C and >90% relative humidity in an C₂H₄-free atmosphere of 2 to 4 kPa O₂ and/or 5to10kPaCO₂.     

Residual NO−3 NO−2, carbonyl and TBA values of Turkish soudjouk manufactured by adding different starter cultures and using different ripening temperatures

No standard technologically based manufacturing method exists for dry, fermented, spicy Turkish style sausage (soudjouk) and current techniques yield techniques yield unacceptable, mostly rancid and putrid products with high levels of residual NO⁻₃ and NO⁻₂. A standard method of soudjouk processing was developed. Three different starter cultures ( Lactobacillus plantarum, L. plantarum+Micrococcus aurantiacus, L. plantarum+M. aurantiacus+Debaryomyces hansenii ) were added to the soudjouk mixture and ripened at three different temperatures (12–14, 16–18 and 20–22°C). The addition of mixed cultures significantly reduced the residual NO⁻₃ and NO⁻₂ levels, increased the lipid soluble carbonyl levels, and produced low thiobarbituric acid values in the ripened soudjouks. For better quality characteristics, addition of D . hansenii is advisable and a ripening temperature of 20-22°C should be used.     

Pasteurization of Beer by a Continuous Dense-phase CO2 System

ABSTRACT: Effects on beer quality were studied after pasteurization by a continuous dense-phase carbon dioxide (DPCD) system. Changes in haze formation, foaming capacity and stability, and objective and subjective aroma and flavor were evaluated, after validation of a 5-log reduction in yeast populations. A maximum log reduction in yeast populations of 7.38 logs was predicted at 26.5 MPa, 21°C, 9.6% CO₂, and 4.77 min residence time. Haze was reduced by DPCD pasteurization from 146 nephelometric turbidity units (NTU) to 95 NTU. At this same treatment combination, aroma and flavor of beer sample means were not considered significantly different ( P = 0.3415) from fresh beer sample means when evaluated in a difference from control test, using fresh beer as the reference. Foam capacity and stability were affected minimally by CO₂ processing; however, changes would most likely be unnoticed by consumers.     

Modeling of O2and CO2 Exchange Dynamics in Modified Atmosphere Packaging of Burlat Cherries

ABSTRACT: A simple mathematical model has been applied to estimate the optimal conditions for modified atmosphere packaging (MAP) of Burlat cherries. The model describes gas exchange in flexible packages, taking into account the respiration rate of the fruit and the transmission rate of gases through the film. The model predicts the evolution of the gas composition inside the package at different conditions. To verify experimentally the model estimations, Burlat cherries were packaged in air and in 3 mixtures of gases at 2 temperatures using 3 different films. Experimental results agree satisfactorily with the predicted values if the O₂ concentration is higher than 2 %.     

Fractionating Soybean Storage Proteins Using Ca2+ and NaHSO3

ABSTRACT:  Individual soybean storage proteins have been identified as having nutraceutical properties, especially β-conglycinin. Several methods to fractionate soy proteins on industrial scales have been published, but there are no commercial products of fractionated soy proteins. The present study addresses this problem by using calcium salts to achieve glycinin-rich and β-conglycinin-rich fractions in high yields and purities. A well-known 3-step fractionation procedure that uses SO_2, NaCl, and pH adjustments was evaluated with CaCl₂ as a substitute for NaCl. Calcium was effective in precipitating residual glycinin, after precipitating a glycinin-rich fraction, into an intermediate fraction at 5 to 10 mM CaCl₂ and pH 6.4, eliminating the contaminant glycinin from the β-conglycinin-rich fraction. Purities of 100%β-conglycinin with unique subunit compositions were obtained after prior precipitation of the glycinin-rich and intermediate fractions. The use of 5 mM SO₂ in combination with 5 mM CaCl₂ in a 2-step fractionation procedure produced the highest purities in the glycinin-rich (85.2%) and β-conglycinin-rich (80.9%) fractions. The glycinin in the glycinin-rich fraction had a unique acidic (62.6%) to basic (37.4%) subunit distribution. The β-conglycinin-rich fraction was approximately evenly distributed among the β-conglycinin subunits (30.9%, 35.8%, and 33.3%, for α', α, and β subunits, respectively). Solids yields and protein yields, as well as purities and subunit compositions, were highly affected by pH and SO₂ and CaCl₂ concentrations.     

Effects of Short-term Exposure to Low O2 and High CO2 Atmospheres on Quality Attributes of Strawberries

Strawberries (Fragaria ananassa Duch., cv. ‘Selva') were stored 10 days in 1.0%, 0.5%, or 0.25% 0₂ or air + 20% CO₂; or 6 days in air + 50% or 80% CO₂ at 0 or 5°C without detrimental effects on quality. Decay and softening were reduced by treatments. An untrained taste panel, under ordinary eating conditions, did not consistently differentiate ‘Pajaro’ strawberries kept in 0.25% 0₂ from those stored in air. A trained taste panel, under controlled conditions, perceived slight off-flavor in ‘G3’ strawberries kept in 0.25% or 0% 0₂. This correlated with ethanol, ethyl acetate, and acetaldehyde in juice. The 50% or 80% CO₂ treatments caused injury after 8 to 10 days, while 20% CO₂ treatments did not. All high CO₂ treatments caused increase in pH of juice.     

COVALENT IMMOBILIZATION OF BOVINE PHOSPHOLIPASE A2

Bovine phospholipase A ₂ (PPLA ₂ ) was immobilized onto controlled pore glass (CPG) beads using four different immobilization methods. PPLA ₂ was immobilized directly to CPG using glutaraldehyde without and with reduction by sodium borohydride (PP1 and PP2). Whey protein isolate was directly immobilized to CPG as a spacer followed by immobilization of PPLA ₂ without and with reduction (PP3 and PP4). Immobilized enzyme samples were characterized with respect to total amount of protein immobilized, activity with a fluorescent substrate and stability over 3 weeks. Among the methods, PP2 and PP4 showed the highest enzyme activity. All methods but PP2 showed a significant decrease in enzyme activity over 3 weeks. Enzyme immobilized by two methods (PP2 and PP4) were compared with soluble enzyme for the hydrolysis of egg phospholipids. Soluble and immobilized enzyme (PP4) resulted in similar free fatty acid values.     

Changes in the free -NH2, free -CO2H and titratable acidity of meat proteins

The 2, 4, 6-trinitrobenzene sulphonic acid (TNBS) spectrophotometric assay and formol titration were used to measure changes in free -NH₂ and free -CO₂H respectively, in meat proteins dissolved in 3% sodium dodecyl sulphate (SDS). Changes in the titratable acidity of the meats was also determined. The free -NH₂ groups were found to decrease markedly with cooking while -CO₂H remained relatively constant. Intermediate moisture beef ( Longissimus dorsi ) processed and stored at 38°C showed the free groups increasing for up to 8 weeks' storage due to proteolysis, followed later by a sharp fall due to cross-linking. But titratable acidity of the IM beef samples continued to rise with storage.     

Biomass and Patulin Production by Byssochlamys nivea in Apple Juice as Affected by Sorbate, Benzoate, SO2 and Temperature

The effects of potassium sorbate, sodium benzoate, SO₂ and incubation temperature on biomass and patulin production by Byssochlamys nivea in apple juice were determined. Growth at 21, 30 and 37°C over a 25-day incubation period was significantly retarded by 75 ppm SO₂, 150 ppm potassium sorbate and 500 ppm sodium benzoate. Biomass accumulated to approximately 500 mg/100 ml in control samples of apple juice. Patulin was produced in the highest concentrations at 21°C after 20 days incubation. After reaching a maximum concentration at 30 and 37°C, a rapid decline in patulin content was observed. Patulin production was also observed at 12°C. On the basis of concentration, SO₂ had the most significant effect on the rate of biomass and patulin production by B. nivea followed by potassium sorbate and sodium benzoate, respectively.     

Supercritical CO2 extraction of grappa volatile compounds

A first study on the recovery of aromatic extracts from grappa by means of supercritical fluid extraction (SFE) on a laboratory plant has been performed, to obtain aroma extracts at low ethanol content. The influence of extraction parameters like pressure, temperature and flow rate have been studied. Extraction yields have been evaluated for ethanol, higher alcohols and esters of short and medium chain acids. A higher aroma volatile compounds extraction has been obtained when the strongest extraction condition has been considered (200 bar, 60 °C, 0.3 kg h⁻¹). Sensory evaluation has indicated as preferred the extract obtained under mild condition (80 bar, 40 °C, 0.3 kg h⁻¹).     

FLAVOR MODIFICATIONS PRODUCED IN ICE CREAM MIX MADE WITH CORN SYRUP. 2. CO2 Production Associated with the Browning Reaction

SUMMARY— Low and high-conversion corn syrups were used to partially replace the sucrose in ice cream mix subsequently heated at various times and temperatures. The effect this practice had on the browning reaction was recorded by the amount of CO₂ evolved during heating. A well-known inhibitor of the browning reaction was added to some mixes before processing. Results indicated that the variables tested significantly influenced the extent of the browning reaction in heated mix. These factors, moreover, exhibited considerable interplay, as shown by the predominance of statistically significant 2- and 3-factor interactions. Corn syrup containing the greatest concentration of reducing sugars was most active in promoting the browning reaction in ice cream mix. The effect of changing any of the variables on the reaction was most marked in mix made with this syrup. Potassium metabisulfite displayed the general effect of lowering the degree of the browning reaction.     

Conversion of Provitamin D3 to Vitamin D3 by Monochromatic Ultraviolet Rays in Fish Dark Muscle Mince

To determine whether the photochemical conversion of provitamin D₃ is possible in fish meat, the dark muscle of skipjack was irradiated with monochromatic ultraviolet rays (peak, 305 nm; range, 280–360 nm) under various conditions of both time of exposure and strength of light. The vitamin D₃ and provitamin D₃ content were analyzed by HPLC. The vitamin D₃ content increased, and the provitamin D₃ content decreased with 20W light at a distance of 50 cm. The conversion was at a maximum 15 hr after the start of irradiation and about 20% of the provitamin D₃ changed to vitamin D₃