摘要:

Mixtures of sodium nitrite, amino acids and ascorbic acid at pH 6.3 or 7.2 were filter sterilized or heated for various times at 121°C. Samples were analyzed for nitrite concentration immediately after treatment and after storage at 37 or 43°C. Heating the complete medium for 15 min at 121°C reduced the nitrite concentration by 30–50% independent of the initial nitrite concentration. Storage of complete filter sterilized medium at 43°C for 18–24 hr resulted in 50–65% loss of nitrite while in heat sterilized medium the loss was as great as 90%. None of the 19 amino acids stored individually with sodium nitrite at 37°C for up to 4 hr affected the nitrite concentration, whereas ascorbic acid resulted in total disappearance of nitrite. During heating at 121°C of the 19 amino acids only cystine resulted in any significant nitrite loss after 15 min of treatment while ascorbic acid effected total nitrite disappearance after 5 min. The defined medium containing nitrite demonstrated inhibitory activity against seven strains ofClostridium

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02760.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Blood protein concentrates were prepared from the serum and decolorized hemoglobin fractions of bovine blood. The emulsifying capacity of the concentrates was dependent on protein concentration and was not affected by spray drying. However, when the serum protein fraction was subjected to the decolorization treatment, its emulsifying capacity was reduced. Lactose, when added to the serum proteins prior to spray drying, prevented this reduction.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02761.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

A technique was pursued for the enrichment of a dried model system by exposure of the system to an atmosphere of volatile flavor compounds. As the exposure time was lengthened, the quantity of each of the flavor compounds absorbed by the freeze‐dried cream increased. Short chain methyl ketones were absorbed by the dehydrated cream in larger amounts than those determined for the higher molecular weight homologs. In these experiments the desorption, during frozen storage, of highly volatile ketones from freeze‐dried cream exposed to 2‐alkanones was greater than that obtained for the high molecular weight homologs. To compensate for the loss of highly volatile flavor constituents during prolonged storage, a dried food product could be enriched above the normal level. Following storage, residual levels of such volatiles would more closely approximate the initial concentration in the food. The application of these findings to a commercial absorption process could be of value in improving the flavor and odor characteristics of a dehydrated food, or in the fabrication of completely new synthetic foods or food an

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02762.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Analytical methods were adapted to the determination of methionine sulfoxide and methionine sulfone in casein. Direct determination by alkaline hydrolysis appears to be more accurate than indirect determination by the carboxymethylation‐performic oxidation method. Proteolysis of casein with Pronase was adopted as an in vitro digestibility test. In the conditions chosen, 41% of the methionine residues of casein were released as free methionine. A solution of casein was treated with up to 0.12M hydrogen peroxide. No methionine sulfone was formed. Most of the methionine residues were oxidized into methionine sulfoxide. When milk was treated with 0.018M hydrogen peroxide, 51% of its methionine residues was transformed into methionine sulfoxide. Hydrogen peroxide‐oxidized casein samples were submitted to the Pronase digestibility test. Release of free methionine was inversely related to the methionine sulfoxide content. No free methionine sulfoxide was released from casein. Release of other amino acids was little affected by hydrogen peroxide treatment. Similar results were found with m

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02763.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Attenuated total reflectance (ATR), offering a possible rapid method for quantitative measurements of major nutritional components in food materials (fat, protein, carbohydrate), was employed to evaluate the composition of a variety of soy products. Using a sample cell developed in this laboratory, different sample particle sizes and forces applied to a mounted sample were investigated to determine if variations of this type would improve the accuracy and precision of the quantitative ATR technique. Correlations of 0.96 for fat and 0.94 for protein were achieved between a chemical analysis and the infrared technique using a baseline absorbance (A′) calculation and 120 mesh samples at 40 lb force. Errors assignable to various aspects of the ATR technique are discusse

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02764.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

The ion‐exchange behaviors of succinic, malic and tartaric acids on Amberlite resins are evaluated. Retention and detector response data on silyl derivatives of several organic acids are presented. A procedure for the purification of grape juice by use of ion‐exchange resins prior to gas chromatography is described. The malic and tartaric acid contents (g/100 ml juice) respectively, of commercially acceptable grapes were found to be: Thompson Seedless 0.25, 0.90; Cardinal 0.31, 0.91; Beauty Seedless 0.19, 0.62; Perlette 0.26, 0.97; Exotic 0.27, 0.36; and Robin 0.41, 0

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02765.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Changes in the principal organic acids and sugars ofScuppernonggrapes (V. rotundifolia) were followed during the ripening season. The vines were sampled bi‐weekly during the initial stages of berry development and then weekly as harvest approached until the “overripe” stage was reached. At the ripe stage, malate and tartrate constituted approximately 90% of organic acids with trace quantities of pyruvic, fumaric, succinic, citric and quinic acids. Glucose, fructose and sucrose constituted approximately 90% of the sugars with trace quantities of galactose and maltose. Malate concentration increased during the early stages of ripening, peaked and decreased to a plateau at the ripe stage. Tartrate decreased steadily until it leveled at the ripe stage. Sugars began to accumulate at veraison, increased rapidly thereafter, and leveled at the ripe stage. At harvest,Scuppernonggrapes contained 1.60% total acid and 9.45% total sugars on a whole berry basis. Individual constituents were 0.67% malate, 0.92% tartrate, 3.86% fructose, 3.98% glucose, and 1.61% su

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02766.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Samples of paprika were heated for varying lengths of time at temperatures between 100 and 150°C. Degradation of carotenoids and production of browning compounds were followed by measuring the absorbance of acetone and water extracts. Color of the paprika and the solvent‐extracted residues was measured by tristimulus calorimetry. Heating at 125°C for 60 min produced an appreciable change in color, with a 23% loss in carotenoids and a 300% increase in browning compounds. The decrease in carotenoid content was directly related to the Hunter “a” value whereas the Hunter “L” value varied with the logarithm of the percent increase in browning compounds. Heating in a nitrogen atmosphere did not change the data appreciably. Addition of lysine and galactose prior to heating produced darker samples but did not affect the carotenoid content. It should be possible to predict the color changes on heating, calculated as Hunter a × L, from either tristimulus or abs

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02767.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

The effects of nitrogen nutrition and day temperature on composition, color and nitrate in VF–145 tomatoes were investigated in growth chambers kept at 20, 25, 30 and 35°C respectively during the days for 14 hr, and at 20° C during the nights for 10 hr. Nitrogen fertilizer application was altered in half the pots in each chamber by supplying them with half‐strength −N Hoagland's #1 solution during the fruit growth period. Tomatoes from fertilized plants (+N) were slightly higher in titratable acidity but lower in solids content than those from the −N plants. Fruits ripening at high day temperature were poor in color while those ripening at below 30°C were more attractive in color. The total, amino, ammonium and nitrate nitrogen contents of the tomato fruits were higher in the +N series than those of –N series. Tomatoes from plants receiving +N treatments contained more nitrate than those receiving −N treatments. Day temperature greatly affected the nitrate content in the tomatoes. In the +N series the nitrate content of the tomatoes decreased from 72.9 ppm to 0.37 ppm as the day temperature increased from 20: to 35°C. In the −N series, the nitrate content ranged from 0.35–1.15 ppm. Accumulation of nitrates in tomatoes appears to be related to the level of nitrate in the nutrient solution and the day temperature. Low day temperature results in accumulation of nitrate because of the low nitrate

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02768.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

At present corn is graded organoleptically into “normal” and various “off‐odor” categories. The possibility of classifying corn odor on the basis of gas chromatographic patterns of headspace volatiles was studied using 60 samples of corn and statistical step‐wise discriminant and regression analyses. Three options for subdividing the patterns into variables and several transformations for quantitation of peak areas were explored. To obtain optimum odor classification, five to seven gas chromatographic features were necessary. When applied to additional samples, classification at an error probability P<0.05 (above 95% confidence level) was obtained for some statistical models. Thus, an objective system is feasible for classification of

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1973.tb02769.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY