Chemical Composition of the Potato as Affected by the Herbicide, Metribuzin: Enzymatic Discoloration, Phenols and Ascorbic Acid Content

The effect of metribuzin (herbicide) applications at pre-emergence (Tr. 1) and pre- and post-emergence (Tr. 2) stages on enzymatic discoloration, phenolic and ascorbic acid contents of Katahdin, Lemhi Russet and Hampton cultivars was investigated. In all the three cultivars Tr. 1 resulted in significantly (p < 0.05) lower phenolic content and enzymatic discoloration and significantly (p < 0.05) higher ascorbic acid than the controls. Tubers from plants receiving Tr. 2 had significantly (p < 0.05) higher phenolic content, enzymatic discoloration and ascorbic acid than Tr. 1. Tubers from Tr. 2 had significantly (p < 0.05) higher ascorbic acid than the controls but did not differ significantly in phenolic content and enzymatic discoloration from the controls. After a storage of 5 months, controls had the highest phenolic content and enzymatic discoloration followed by Tr. 1 and Tr. 2 for two of the three cultivars. Tr. 2 resulted in a retardation of phenol synthesis during storage.     

Potato Quality as Affected by Source of Magnesium Fertilizer: Nitrogen, Minerals, and Ascorbic Acid

TWO SOURCES of magnesium fertilizer, Epsom salt and dolomite, were compared as to their effect on nitrogen, mineral, and ascorbic acid contents of Katahdin potatoes. Both Mg sources increased significantly (p < 0.05) the total, nonprotein, and protein nitrogen of both cortex and pith tissues. The pith tissue was significantly (p < 0.05) higher than the cortex in total and nonprotein nitrogen. Potatoes fertilized with Epsom salt were higher in nitrogen than those receiving dolomite. Both sources of Mg significantly (p < 0.05) increased Al and Fe contents of tubers, and the greater increase occurred with Epsom salt. Tubers from soils receiving dolomite were significantly (p < 0.05) higher in manganese and cadmium contents than those receiving Epsom salt. No significant differences were observed in ascorbic acid content with either Mg source.     

EFFECT OF PACKAGING MATERIAL ON THE QUALITY OF POTATOES TREATED WITH ISOPROPYL N-(3-CHLOROPHENYL) CARBAMATE (CIPC)

Katahdin and Russet Burbank potatoes, treated with isopropyl N-3(-chlorophenl) carbamate CIPC and stored for four months at 5C in either mesh or polyethylene bags (two packaging materials frequently used for potato storage), were tested for enzymatic discoloration, phenolic and ascorbic acid concentration. CIPC residues in tubers stored in polyethylene bags were significantly (p < 0.0l) higher than those stored in mesh bags. Tubers stored in polyethylene showed significantly (p<0.05) higher discoloration and phenolic concentration, and lower ascorbic acid concentration than those stored in mesh bags. Differences in CIPC retention of the tubers stored in the two packaging materials may have been responsible for some of the differences in quality factors since CIPC was shown to significantly (p<0.0l) increase the enzymatic discoloration and phenolic concentration, and decrease the ascorbic acid concentration of both cultivars.     

Effect of Baking and Frying on Nutritive Value of Potatoes. Nitrogenous Constituents

The effect of conventional baking and frying on the content of total and nonprotein nitrogen of Katahdin, Chipbelle and Rosa varieties of potatoes was investigated. The cortex and pith tissues of the tubers were analyzed separately. In cortex tissue, baking reduced the total nitrogen (5–18%) and total amino acids (5%). In pith tissue, baking increased total nitrogen (3–20%), nonprotein nitrogen (9–28%), and total amino acids (13%). During baking migration of nitrogen constituents from cortex to pith tissue occurred in all three varieties. In cortex tissue frying decreased significantly the total nitrogen (29–43%), nonprotein nitrogen (20–35%) and amino acid content (45%). A similar trend was observed in the pith tissue. Greater losses in total, nonprotein nitrogen and amino acids occurred with frying than with baking.     

Ascorbic Acid and Protein Content of Potatoes in Relation to Tuber Anatomy

Localization of the nutrients ascorbic acid and protein in the tuber was investigated. Katahdin, Norking Russet, and Shepody potato cultivars were used in this study. Cortex and pith areas were compared for ascorbic acid and protein content. Ascorbic acid of all the three cultivars was significantly higher (p<0.01) in the pith than in the outer cortex region and the protein content was significantly higher (p<0.01) in the cortex than the pith area. The pith region was significantly (p<0.05) higher in nonprotein nitrogen than the cortex area. Since only 2% of the protein content of the entire tuber was located in the peel, peeling the tuber did not cause a significant loss of protein.     

Effect of Zinc Fertilization on Yield, Enzymatic Discoloration, Phenolic and Nitrogenous Constituents of Potato Tubers

The effect of zinc fertilization on yield, enzymatic discoloration, phenolic and nitrogenous constituents of Katahdin potatoes was studied. Zinc sulfate was banded in the soil at the time of planting at rates of 0, 20, 40, and 100 1b/acre. Application of 100 1b/acre zinc reduced significantly the total yield and especially U.S. #l yields of potatoes, but no significant differences in yield were observed up to 40 1b/acre zinc sulfate. Zinc fertilization significantly reduced phenolic content and discoloration of tubers. Nonprotein nitrogen and free amino acid contents were reduced at all levels of zinc application, and total nitrogen was significantly reduced at the 100 1b/acre level.     

Effect of Molybdenum Fertilization on the Nitrogenous Constituents of Potatoes

The effect of molybdenum fertilizer on the nitrogenous constituents of Katahdin potatoes was investigated. The chemical constituents studied were total nitrogen, nonprotein nitrogen, and protein. Sodium molybdate was applied to the soil at rates of 0.0, 2.8, 6.7 and 10.1 kg/ha during the first year and 0.0, 5.6, 16.8 and 22.4 kg/ha during the second year of the study. The compound was applied to the soil one day prior to planting of the seed potatoes. During both years of the study, tubers from plants receiving molybdenum fertilization were significantly higher (p < 0.01) than the controls in total nitrogen and protein and significantly lower (p < 0.01) in nonprotein nitrogen at all levels of molybdenum application. Greatest increases in total nitrogen and protein were observed in tubers from plants receiving 22.4 kg/ha of sodium molybdate.     

Effect of Phosfon D on the Amino Acid Content and Protein Quality of Two Snap Bean Cultivars

Two cultivars of snap beans, Phaseolus vulgaris L. were treated with soil applications of Phosfon D, a growth retardant, at 10⁻³M and 10⁻³M concentrations. Total nitrogen and ammo acids were determined on the bean pods of the two cultivars and in the treated pods. Cultivar and treatment differences in amino acid content were found. Phosfon D stimulated the synthesis of nonprotein nitrogen compounds in the cultivar Eagle and increased the synthesis of amino acids in the cultivar Nemasnap. Differences in the amino acids were not sufficiently large to change the protein quality in the snap beans. The limiting amino acid in the snap beans was methionine.     

CONTENT OF BASIC COMPONENTS AND VOLATILE OILS IN GREEN DILL AS DEPENDING ON THE HEIGHT AND USABLE PARTS OF PLANTS

The aim of the present study was to establish the content of basic chemical components (dry matter, ash, reducing sugars, total sugars, starch, dietary fiber, total nitrogen, protein nitrogen, ascorbic acid, titratable acidity) and volatile oils in dill plants. The investigated material consisted of the following parts of dill plants: leaf blade, petiole, whole leaf, stem and whole plants harvested at the plant height of 20, 30, 40, 50 and 60 cm. Differences in the level of the analyzed components depending on the part of dill plants to a great degree exceeded these depending on the plant height. The highest content of all components was ascertained in the leaf blade. The smallest contents of dry matter, ash, starch, dietary fiber, total nitrogen and protein nitrogen, total acids and L‐ascorbic acid were found in the stem, and of sugars and volatile oils in the petiole. With the growth of plants, all analyses showed decreasing tendencies in the content of ash, total nitrogen and protein nitrogen, variation in the level of dry matter, sugars, starch and L‐ascorbic acid, and an increasing tendency in the content of dietary fiber, total acids and volatile oils, with the exception of stems, where the level of volatile oils was stable.     

Amino Acid Profiles of Common Cultivated Mushrooms Including the Identification of N-(N-γ-L-Glutamyl-3-Sulfo-L-Alanyl)Glycine in Flammulina velutipes

Amino acid profiles of nonprotein nitrogen (NPN) and protein nitrogen (PN) fractions of common cultivated mushrooms were determined. Free amino acids in the NPN fractions were generally characterized by the predominant occurrence of alanine and amino acids metabolically related to the glutamic acid family and also by the common presence of unique nonprotein amino acids, such as saccharopine, cystathionine and ethanolamine. A novel glutathione analog, N-(N-γ-L-glutamyl-3-sulfo-L-alanyl)glycine, was found in Flammulina velutipes. The proportion of the NPN to the total nitrogen was relatively high and large amounts of the NPN were made up of free amino acids and related compounds. Protein amino acids in the NPN and PN fractions accounted for about 65% of the total nitrogen, suggesting that a practical nitrogen-protein conversion factor for the mushrooms may be considered to be about 4 on the average.     

FREE AMINO ACIDS AND DIPEPTIDES IN DRY-CURED HAM

Six types of dry-cured hams were chemically profiled for proximate composition and low molecular weight nonprotein nitrogen (NPN) fractions including free amino acids (FAA) and two dipeptides (carnosine and anserine). Results indicate that FAA were present in the six classes at different (mg/100g protein) concentrations, with Iberian and Serrano containing greater (P<0.05) amounts of most FAA. However, when analyzed as percentage (mg/100g total FAAs) values, FAA contents of Iberian and Serrano hams exhibited lower (P<0.05) tyrosine and greater (P<0.05) aspartic acid and threonine values. Within each class, large variation coefficients (>10%) for nonprotein nitrogen paralleled inconsistent values of salt content, to which NPN and FAAs were negatively correlated (P<0.01). NPN was also negatively affected by moisture in the dried muscle, indicating limited saltiness and greater muscle shrinkage as two major determinants in developing of nonprotein fractions, hence of free amino acids.     

Lipid Oxidation in Microsomal Fraction of Squid Muscle (Loligo peali)

Frozen squid is susceptible to both lipid oxidation and yellow/brown discoloration during frozen storage. The involvement of lipid oxidation in the microsomal fraction of squid muscle on oxidative rancidity and discoloration was investigated using iron and either enzymatic or non‐enzymatic redox cycling pathways. Lipid oxidation was measured by thiobarbituric acid‐reactive substances (TBARS), and color changes were measured spectrophotometrically using an integrating sphere. The lipid oxidation was not observed in the squid microsomes in the presence of Fe³⁺ and β‐nicotinamide adenine dinucleotide disodium salt (NADH) or β‐nicotinamide adenine dinucleotide phosphate, reduced (NADPH), suggesting that the enzymatic redox cycling pathway was not active. Iron‐promoted TBARS formation was observed in the non‐enzymatic pathway when ascorbic acid was used as a reducing compound. Non‐enzymatic lipid oxidation increased with increasing temperature (4 °C to 37 °C), iron (0 to 100 μM), and ascorbic acid (0 to 200 μM) concentrations. As lipid oxidation in the microsomes or isolated microsomal lipids increased, color changes were observed as could be seen by an increase in b* values (yellowness) and a decrease in a* (redness) values. The ability of iron and ascorbate to promote both lipid oxidation and pigment formation in the microsomal fraction suggests that this pathway could be responsible for quality deterioration of squid muscle during storage.     

Effect of Packaging Materials on the Chemical Composition of Potatoes

Russet Burbank and Chieftain potatoes were packaged in either mesh, paper or polyethylene bags and compared in chemical composition after 1, 4, and 8 wk of storage at 20^oC. Potatoes were analyzed for weight loss, discoloration, phenols, ascorbic acid, glycoalkaloids and nitrate-nitrogen. Potatoes packaged in polyethylene were lowest in weight loss, ascorbic acid and nitrate-nitrogen and highest in discoloration, phenols and glycoalkaloids than those packaged in mesh or paper. Potatoes packaged in paper were lowest in discoloration and phenols and highest in ascorbic acid. There were no significant differences in weight loss, glycoalkaloids or nitrate-nitrogen between potatoes packaged in mesh on paper.     

Free Amino Acids and Related Compounds in Seeds and Sprouts of Winged Bean Psophocarpus tetragonolobus (L.) DC)

Free amino acids and related compounds in the nonprotein nitrogen (NPN) fraction of winged bean seeds and sprouts were quantitatively determined. The proportion of NPN to total nitrogen was low in the seeds (9%) and in the cotyledons of the sprouts (11%), and relatively high in the epicotyls of the sprouts (54%). About 6% and 40% NPN were attributable to free amino acid nitrogen in the seeds and the sprouts, respectively. The free amino acid profile of seeds was characterized by the presence of sizable amounts of γ-L-glutamyl-L-tyrosine and γ-L-glutamyl-L-phenylalanine, indicating similarities to that of soybean seeds. Accumulation of free amino acids, particularly nonprotein amino acids such as α-aminoadipic acid and γ-aminobutyric acid, were demonstrated in the sprouts. No canavanine was detected in either seeds or sprouts.     

冷冻对马铃薯品质的影响

新鲜马铃薯在-20℃冷冻24h,然后在20℃解冻1h,接着对其组织状态、Vc流失、酶促变色和矿物质含量等指标进行测试分析,并与未经冷冻处理的对照组进行比较,以研究冷冻对马铃薯品质的影响。     

Evaluation of chemical parameters in soft mold-ripened cheese during ripening by mid-infrared spectroscopy

The suitability of mid-infrared spectroscopy (MIR) to follow the evolution throughout ripening of specific physicochemical parameters in Camembert-type cheeses was evaluated. The infrared spectra were obtained directly from raw cheese samples deposited on an attenuated total reflectance crystal. Significant correlations were observed between physicochemical data, pH, acid-soluble nitrogen, nonprotein nitrogen, ammonia (NH₄⁺), lactose, and lactic acid. Dry matter showed significant correlation only with lactose and nonprotein nitrogen. Principal components analysis factorial maps of physicochemical data showed a ripening evolution in 2 steps, from d 1 to d 7 and from d 8 to d 27, similar to that observed previously from infrared spectral data. Partial least squares regressions made it possible to obtain good prediction models for dry matter, acid-soluble nitrogen, nonprotein nitrogen, lactose, lactic acid, and NH₄⁺ values from spectral data of raw cheese. The values of 3 statistical parameters (coefficient of determination, root mean square error of cross validation, and ratio prediction deviation) are satisfactory. Less precise models were obtained for pH.     

Comparison of bioactive components in GABA tea and green tea produced in Taiwan

The aim of this study is to investigate the bioactive components of GABA (γ-aminobutyric acid) tea as compared with green tea produced in Taiwan. Using in total 56 tea samples (28 green tea and 28 GABA tea), moisture content, Hunter L, a and b values, phenolic compounds, amino acids including GABA, fatty acids and ascorbic acid were determined. The results showed that moisture, total free amino acids, crude fat, Hunter L value, total nitrogen, free fatty acids and reducing sugar did not differ significantly between GABA tea and green tea. However, GABA tea had higher Hunter a and b values, while green tea had higher total catechin and ascorbic acid contents (p < 0.05). Of major catechins, epicatechin and epigallocatechin gallate were found to be lower in GABA tea than in green tea. For free amino acids, GABA, alanine, ammonia, lysine, leucine and isoleucine were found to be significantly higher in GABA tea, while the glutamic acid, aspartic acid, and phenylalanine were higher in green tea (p < 0.05). Theanine, tryptophan, valine, threonine and methionine were not found to be different between the two kinds of tea.     

QUALITY OF FRESH-CUT TOMATOES

Tomato fruit at pink or light-red stages of ripening were cut into slices, rinsed with water containing 50 μL.L⁻¹ sodium hypochlorite and drained. They were stored in perforated polyethylene package at 1C in air or controlled atmosphere for five and ten days. Weight loss, chlorophyll and lycopene contents, seed discoloration, fungal infection, total soluble solids content, titratable acidity, sugar/acid ratio, pH, flavor and taste, firmness, ascorbic acid content, rate of respiration and ethylene production, and electrolyte leakage were evaluated after each storage period. The overall quality of controlled atmosphere-stored slices was better than that of air stored slices. Slices from light-red fruit had lower weight loss, minimum seed discoloration, lower     

Changes in Total Phenolic, Total Glycoalkaloid, and Ascorbic Acid Content of Potatoes as a Result of Bruising

The effect of bruising on total phenols, total glycoal/kaloids (TGA), and ascorbic acid content of Katahdin potatoes was studied. Following bruising, tubers were stored at either 5° or 20°C for I, 3, 6, and I2 wk. Unbruised whole tubers served as controls and bruised halves were compared with unbruised halves. Both halves of bruised tubers were higher in phenols, TGA and lower in ascorbic acid than unbruised controls. Bruised halves contained significantly more phenols, TGA and less ascorbic acid than unbruised halves. Storage temperature did not affect ascorbic acid content but the greatest accumulation of phenols occurred at 5°C and the highest TGA at 20°C storage temperature. Cortex tissue was significantly lower in ascorbic acid than pith tissue.     

CHANGES IN NITROGEN FRACTIONS AND FREE AMINO ACIDS DURING RIPENING OF SPANISH DRIED BEEF "CECINA"

The changes in nitrogen fractions (total nonprotein nitrogen -NPN-, amino acid nitrogen, peptide nitrogen and volatile basic nitrogen) and free amino acids during the ripening of "cecina" (a Spanish dried beef product) were tracked. The amount of total NPN, amino acid nitrogen and volatile basic nitrogen increased during processing, while peptide nitrogen decreased in the last stage. An increase was observed in all amino acids except taurine. In the final product, the most abundant free amino acids were leucine-isoleucine mixture, lysine and proline-methionine mixture. Taking into account the concentrations of the most abundant amino acids detected in cecina and the taste thresholds described for L-amino acids in water, it appears that several amino acids i.e. lysine, alanine, valine and glutamic acid, could contribute to the flavor of this meat product.