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 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.     

Effect of Foliar Application of Auxin on the Quality of Potatoes

Katahdin and Kennebec potatoes were sprayed with 10^?5M auxin at the beginning of flowering. Tubers from the auxin-treated plants were compared with untreated controls for phenolic content, enzymatic discoloration, total nitrogen, nonprotein nitrogen, free ammo acids, lipids, minerals, and ascorbic acid content. In both varieties auxin increased the phenols and enzymatic discoloration. However, no differences were observed in fatty acid composition and ascorbic acid content. Total nitrogen, nonprotein nitrogen, free amino acids, crude lipid, phospholipid and magnesium content were higher, and iron lower, in Katahdin tubers from the treated plants.     

Effect of Sprout Inhibitors and Nitrogen Fertilization on Nitrate-N Content of Potato Tubers

The effect of sprout inhibitors, maleic hydrazide (MH), and isopropyl-N-(3-chlorophenyl)-carbamate (CIPC), on nitiate-N (NO₃-N) content of tubers was investigated. The effect of rate of application of nitrogen fertilizer and variety on NO₃-N content of tubers was also examined. Foliar application of MH significantly (p < 0.01) increased NO₃-N content of the tubers. NO₃-N content increased significantly (p < 0.01) with increasing amounts of MH application. No significant differences in NO₃-N content of tubers were observed with CIPC treatment. NO₃-N content increased significantly (p < 0.05) in tubers with increasing nitrogen fertilization rates. Varieties differed in their NO₃-N content. The NO₃-N content of the cortex was significantly (p < 0.05) higher than the corresponding pith tissue regardless of treatment.     

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.     

GLYCOALKALOID CONTENT OF NEWFOUNDLAND GROWN POTATO TUBERS AND POTATO WART TISSUE

Eight cultivars of potato tubers grown in Newfoundland were examined for total glycoalkaloids (TGA) at harvest and after 3, 6, 9 or 12 days exposure to 150 footcandles light. Freshly harvested tubers had TGA ranging from 0.9 to 15.4 mg/100 g of total tuber tissue. TGA increased as a result of long term light exposure in all cases; however, those cultivars surface-pigmented with red or blue anthocyanins were less responsive to light induction. TGA in light exposed tubers ranged from 52–71 mg/100 g for white cultivars, 26–46 mg/100 g for red varieties, and 23–40 mg/100 g for those pigmented with blue anthocyanins. Healthy tubers from plants afflicted with potato wart did not show abnormally high TGA; however, healthy cankers contained as high as 170 mg/100 g. Greening or decomposition of wart tissue was associated with a decline in TGA. Thin-layer chromatography revealed α-solanine and α-chanconine were the principal components in TGA extracts of both tubers and wart tissue.     

EFFECTS OF VARIETY AND GROWTH SEASON ON THE ORGANOLEPTIC AND NUTRITIONAL QUALITY OF HYDROPONICALLY GROWN TOMATO

The effects of variety and season on several organoleptic and nutritional quality parameters (i.e., dry weight (dw), total sugars, soluble solid compounds, titratable acidity (TA), electrical conductivity (EC), juiciness, firmness, vitamin C (vit C), total phenolic compounds, hydrophilic antioxidant capacity and minerals) of five different varieties of tomatoes (i.e., Jack, Cabrales, Jaguar, Iker and Nevada) grown in two crop cycles (spring and autumn) were studied. Each variety presented its own specific characteristics regarding the chosen parameters. Firmness, TA and EC were season dependent, whereas soluble solids content did not change between cycles. In some varieties, the dw, juiciness and total sugars were affected by climatic conditions. The total phenolic compounds and the hydrophilic antioxidant capacity were variety dependent in both cycles. By contrast, the vit C content was variety dependent only in the autumn cycle. Similarly, these latter parameters (phenolic compounds, hydrophilic antioxidant capacity and vit C) were also season dependent, showing higher values in the spring than in the autumn cycle. The effect of tomato variety and season on mineral contents is also discussed. Those tomatoes grown in the spring cycle had better quality according to the organoleptic parameters studied here as well as to a higher antioxidant capacity. The percentages of the recommended dietary allowances supplied by the studied tomatoes were not significantly affected by variety or season, despite differences in their physicochemical compositions.     

发酵剂及猕猴桃蛋白酶促进马肉发酵香肠蛋白质的降解

为了提高马肉发酵香肠的品质,添加发酵剂和猕猴桃蛋白酶,促进其发酵成熟和肌肉蛋白质的降解。以新鲜马肉和马脂肪为原料,分别设计三个试验组,一组为对照组,另两组为处理组;对照组不采取处理,而两个处理组添加2%的发酵剂和0.05%的猕猴桃蛋白酶,并在相应条件下进行发酵,检测其总氮、非蛋白氮等指标,并通过SDS-PAGE电泳分析其肌肉蛋白质的降解情况。结果表明,灌肠后(0 d)各组总氮含量为3.09 g/100 g左右,而加工结束后(28 d),对照组(CK组)、发酵组(A组)、猕猴桃蛋白酶组(B组)总氮含量分别是3.41 g/100 g、3.85 g/100 g及4.15 g/100 g,说明总氮含量明显上升,并且发酵剂和猕猴桃蛋白酶的影响显著;28 d CK组、A组、B组非蛋白氮含量分别为0.42 g/100 g、0.52 g/100 g、0.65 g/100 g,与0 d非蛋白氮含量0.22 g/100 g相比,CK组上升1.9倍,A组上升2.4倍,B组上升2.9倍;SDS-PAGE电泳结果表明,在整个加工过程中A组与B组肌浆蛋白逐渐发生降解,大分子条带发生了明显的变化,发酵剂对马肉发酵香肠肌浆蛋白和肌原纤维蛋白的降解有显著的促进作用,猕猴桃蛋白酶对肌浆蛋白的影响显著,并比发酵剂大,但对肌原纤维蛋白的作用不大。     

Effect of Baking and Frying on Nutritive Value of Potatoes: Minerals

The effect of conventional baking and frying on the mineral content of Katahdin, Chipbelle and Rosa varieties of potatoes was investigated. The cortex and pith tissues of the tubers were used. Conventional baking reduced the cortical content of potassium, phosphorus, and iron by 10–13%, 4–21%, and 19–31% respectively. In all three varieties, movement of potassium, phosphorus, and iron toward the interior tissues was demonstiated during conventional baking although varieties varied widely in their mineral content. Conventional baking increased the pith content of potassium (14–23%), phosphorus (2–9%), and iron (2–8%). Frying decreased significantly all the minerals in both the cortical and pith areas with the major loss occurring in the cortical area (10–45%).     

METABOLISM OF SOLANINE AND CHLOROPHYLL IN POTATO TUBERS AS AFFECTED BY LIGHT AND SPECIFIC CHEMICALS

SUMMARY— Chlorophyll and solanine syntheses as affected by cultivars, specific gravities, light intensities, and chemicals were studied in potato (Solanum tuberosum, L.) tubers. When exposed to 100 ft-c of while fluorescent light for 5 days, tubers of Bounty, Kennebec, Norchip and Red Lasoda were most sensitive to greening and solanine development. LaChipper and Platte tubers were resistant to the light effects. Chlorophyll synthesis was inversely related to specific gravity of tubers, while specific gravity did not affect solanine synthesis. The chlorophyll content of tubers exposed to 50 ft-c and 200 ft-c was significantly less than that of tubers exposed to 100 ft-c and 150 ft-c light intensities. The solanine synthesis was not influenced by the light intensities studied. Chemicals were applied at a concentration of 10,000 ppm by vacuum injection technique. Ethrel® and Alar® were effective in inhibiting chlorophyll and solanine formation. Ethrel was more effective in retarding the chlorophyll formation and alar was most effective in preventing solanine formation. Maleic hydrazide MH®-30 and Cyocel® were ineffective in controlling both chlorophyll and solanine formation.     

Changes in proteins and amino acids in developing soybean seed and effect of phosphorus nutrition

Two varieties of soybean (Bragg and Punjab-I) grown in pot culture with three levels of phosphorus were studied for the changes in protein content, ether extract, amino acids and protein fractions during the development of the seed, and the effect of phosphorus nutrition thereon was also studied. The non-protein nitrogen, which formed a substantial portion of total nitrogen at early milky stage, decreased and true protein increased as the seed matured, but crude protein did not seem to alter much during the seed development, whereas ether extract gradually increased with maturity. The concentrations of free amino acids such as lysine, hydroxy-proline and tryptophan decreased whereas those of glutamic acid and alanine increased as the seed approached maturity. However, the total concentration of methionine and tryptophan in the protein of the seed was not much affected by maturity. The albumin fraction decreased from the early milky stage to the maturity stage. Glutelin rapidly increased from the early milky stage to mid-milky stage and sharply declined at the mature stage whereas the glycinin fraction rapidly increased from mid-milky to the mature stage of seed development. The prolamine fraction did not vary during seed development. Phosphorus application increased crude protein and true protein and decreased ether extract but had little effect on amino acids and protein fractions.     

THE EFFECT OF SOIL ENTRAPMENT BY THE PERIDERM ON THE MINERAL ELEMENT COMPOSITION OF POTATOES

The effect of soil entrapment on the mineral element concentration in potatoes, Solanum tuberosum L., cv ‘Katahdin,’‘Norking Russet’ and ‘Shepody,’was studied. Titanium was used as the marker element to correct for contamination by soil. Soil entrapment was a significant factor contributing to increases in tuber mineral element concentrations due to the presence of soil in the tissue surface, especially for Al and Fe. Among the macroelements, Ca and Mg concentrations showed a significant increase. Among the microelements, the greatest increases in concentration due to entrapment were observed for Al (95%) and Fe (88%), less for Mn (4%), and generally none for Cd, Co, Cu and Zn. Highest concentrations of elements, including (the potentially toxic element) Al, were found in the peel and least in the pith. The three cultivars showed differences in the accumulation of mineral elements in the peel, with the rougher peel showing the greatest soil entrapment. Boiling resulted in significant decreases in macroelements and increases of microelements in the peel. Tubers in this experiment were cultivated on uncontaminated soil. For tubers grown in soils containing appreciable concentrations of nutritionally undesirable mineral elements, peeling before cooking would greatly facilitate their removal.     

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.     

Non-protein nitrogen in infant cereals affected by industrial processing

The effects of industrial processing on non-protein content in four varieties of infant cereals, so-called ‘Multicereal' and ‘Wheat' as gluten infant cereals, and ‘Growth' and ‘Rice and carrot' as gluten-free infant cereals were determined. Samples were classified according to their industrial stage of treatment: (1) mixture of raw flours; (2) mixture of roasted flours; (3) mixture of enzymatically hydrolysed and drum-dried flours (film); (4) commercial infant cereals. Total nitrogen (TN), protein nitrogen (PN) and non-protein nitrogen (NPN) contents were higher in gluten infant cereals than in gluten-free infant cereals. NPN content was always higher than PN content in all cereals. Industrial processing led to a significant increase in NPN (P<0.01) and free amino acid contents (P<0.001), whereas TN and PN contents decreased significantly (P<0.05). Although non-amino acid nitrogen components remained stable with the industrial processing, a high content of ammonium was found in gluten-free infant cereals as a consequence of taurine and asparagine degradation.     

EFFECT OF SELENIUM FERTILIZATION ON THE GLYCOALKALOID AND NITRATE-NITROGEN CONTENT OF POTATOES

The effect of soil applications of sodium selenite (Na₂SeO₃) on the total glycoalkaloid (TGA) and nitrate-nitrogen (NO₃-N) contents of Katahdin potatoes was studied over two storage periods (0 and 5 month) during each of two years. Sodium selenite was banded to the soil at rates of 0.0, 5.6 (2.5), 11.2 (5.0) and 18.0 (7.5) kg/ha (ppm). Selenium treatment, at all levels, resulted in significantly lower TGA and NO₃-N contents than the controls. Applications of Na₂SeO₃ greater than 5.6 kg/ha did not result in further decreases in the TGA and NO₃-N content. These results were consistent for the two storage periods.     

Correlations between some nitrogen fractions,lysine, histidine,tyrosine, and ornithine contents during the germination of peas,beans, and lentils

The effect of different germination conditions, namely, germination time and total presence or absence of light, on the content of the various nitrogen fractions, three essential protein amino acids (Lys, His, and Tyr) and one non-protein amino acid (Orn), was studied in peas, beans, and lentils. The influence of light during germination on the parameters considered varied according to the legume but on the whole was less important than the influence of germination time in quantitative terms. In all three legumes, prolonging the germination time yielded flours that contained more non-protein nitrogen (NPN) and Orn and less protein nitrogen (PN) and Lys, while the changes in the His and Tyr contents varied with legume type. In addition, changes in the Lys, Tyr, and Orn contents correlated with the changes in the NPN and PN levels in the germinated legumes.     

羊乳酒在发酵过程中主要参数变化的研究

以新鲜羊奶为原料,采用乳酸菌和酵母菌共发酵方法,在29 ℃条件下振荡发酵羊乳,以pH值、酒精度、总氮及非蛋白氮含量为评价指标,通过凯氏定氮法、十二烷基硫酸钠-聚丙烯酰氨凝胶电泳法（SDS-PAGE）,对羊乳酒在发酵过程的不同时期蛋白质降解的动态变化进行了研究。研究结果表明,羊乳酒在发酵的过程中的pH值呈现先降低后升高再降至稳定的趋势;酒精度呈现缓慢增长的趋势;总氮含量变化不大;非蛋白氮含量随着乳酒发酵的进行缓慢升高;SDS-PAGE结果显示,羊乳酒中蛋白质发生了不同程度的降解,小分子蛋白增多,蛋白分子质量主要分布在17～35 kDa。     

不同产蛋白酶乳酸菌对风干牛肉蛋白质降解的影响

为探究产蛋白酶乳酸菌在风干牛肉发酵过程中对肌原纤维蛋白的影响.以牛肉为研究对象,分别接种乳酸乳球菌(S-1)、格氏乳球菌(S-2)、戊糖片球菌(S-3)制备风干牛肉,以不添加发酵剂的样品为对照组(CK),采用理化分析和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacryla...     

Isolation and composition of proteins from leaves of plants grown in Ceylon

Proteins were isolated from fresh leaves of twelve plant species grown in Ceylon. Contents of total N, non-protein N and protein N in the original leaves, and protein N in the isolated protein were determined and the percentage extractability of N was calculated. Analyses of the protein isolates for total N, ash, Ca, Fe and all the amino acids are reported. The protein isolates were rich in all but one of the amino acids namely methionine. However, the lysine contents were greater than in some standard proteins. The protein scores were comparable to the standard proteins. The percentage extractability ranged from 9.3 to 91 %. A high proportion of the nitrogen Was found as non-protein. It was concluded that the proteins from the leaves examined could provide a dietary supplement.     

Proteolysis in dry fermented sausages: The effect of selected exogenous proteases

The effect of three commercial proteases (pronase E from Streptomyces griseus, aspartyl proteinase from Aspergillus oryzae and papain) on protein breakdown and the sensory characteristics of dry fermented sausages was investigated. Water soluble, non-protein, 5% phosphotungstic acid soluble, 5% sulphosalicylic acid soluble and total volatile basic nitrogen contents increased during fermentation, stabilizing later until the end of ripening (26th day). Nitrogen values were always greater in the aspartyl proteinase added batch in comparison with the other protease added batches. Total free amino acid changes showed a similar pattern to those observed for the 5% sulphosalicylic acid soluble nitrogen. The electrophoretic studies demonstrated that proteolysis of high molecular weight myofibrillar and sarcoplasmic proteins was more prominent in protease added batches. It was especially intensive in papain one. The dominant amino acids at the end of ripening were similar in all batches. Tyramine and histamine increased throughout ripening. No significant differences in sensory properties were found between control and pronase E and papain added batches, but they were significantly different (p < 0.01) from the sausages containing aspartyl proteinase, due to an excessive softening. The effect of exogenous enzyme addition on the flavour potentiation of dry fermented sausage is discussed.