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.     

Ca, Fe and Zn Content of'Jewel'Sweet Potato Greens as Affected by Harvesting Practices

A total of 64 “Jewel” sweet potato green samples collected at the end of the growing season, were analyzed to determine and compare the effects of multiple topping on dry matter, calcium, iron and zinc contents of “younger” 4-inch leaf and stem-petiole tips with “older” 4-inch portions of the same material. Older material contained the highest concentration of the minerals, and the concentration in both “young” and “old” plant material wasunaffected by yearly planting. When the mineral content was compared to the Recommended Daily Dietary Allowance for adults it was relatively good.     

Ascorbic Acid Retention in Shredded Iceberg Lettuce as Affected by Minimal Processing

The effects of slicing method, packaging atmosphere and storage temperature were determined on total ascorbic acid (TAA) content of modified atmosphere packaged shredded lettuce. TAA was extracted from the lettuce samples and levels were monitored using either titration with 2,6-dichlorophenolindophenol solution or an assay kit. Slicing affected (p<0.05) ascorbic acid retention in the order manual tearing > manual slicing > machine slicing. Flushing with 100% nitrogen increased retention (～5%, p<0.05) over packages with product modified atmospheres. Storage at 3°C increased retention (～20%, p<0.05) compared with storage at 8°C. Scores for product appearance generally followed losses of TAA in the lettuce (p<0.05).     

Carrot Pulp Chemical Composition, Color, and Water-holding Capacity as Affected by Blanching

Our objectives were to investigate the effect of blanching on nutrients, color, α- and β-carotenes, dietary fiber, and water-holding capacity of carrot pulp after juice was extracted. Carrot pulp contained 4-5% protein, 8-9% reducing sugars, and 5-6% minerals. Compared to the color of fresh carrot juice, pulp from blanched carrots retained redness color values better than that from unblanched carrots. Pulp contained from unblanched: 17% and from blanched: 31-35% of the total α- and β carotenes in the fresh carrots. Glucose and galacturonic acid were predominant sugars of the nonstarchy polysaccharides (NSP) in carrots. Pulp contained 37-48% total dietary fiber and had a high water-holding capacity (WHC), ranging from 9.42 to 10.52g water/g organic matter. Considering carotenes, WHC, and fiber content, carrot pulp products are a good source of dietary fiber.     

Chemical Composition and Color of Strained Carrots as Affected by Processing

The effects of processing line location, holding temperature prior to retorting (82.7, 87.8, and 93.3°C) and retort temperature (118.3, 121.1, and 123.9°C) on chemical composition and color of strained carrots was evaluated. Hunter L, chroma and hue values, and glucose and fructose levels decreased as strained carrots were transferred from batch to holding tanks. Strained carrots held in batch tanks at 93.3°C had less total soluble phenolics, glucose and fructose than those held at 87.8°C and 82.2°C. Carrots retorted at 123.9°C had lower Hunter L and chroma values, and greater levels of total soluble phenolics than those retorted at 118.3 and 121.1°C.     

Acid Milk Gel Formation as Affected by Total Solids Content

Reconstituted skim milk with varying concentrations of total solids was coagulated using glucono-δ-lactone (GDL). Microscopic, turbidimetric and rheological procedures were used to examine mineral solubilization, buffering capacity, casein dissociation and micellar solvation during gelation. Total solids of the milk affected pH of the onset of gelation attributable to differences in colloïdal calcium phosphate in the casein particles during acidification. Firmness and elasticity of the resulting gel increased with total solids from a more direct contribution of dry matter during the last stage of acid milk gel formation.     

Composition of Raw and Cooked Potato Peel and Flesh: Amino Acid Content

The nitrogen and total amino acid contents of Katahdin and Pontiac varieties of potatoes are reported for the peel and flesh, before and after cooking. With the exception of glutamic acid and 7-amino-butyric acid, all of the contents were higher in the peel. Losses of nitrogen and amino acids were minor in boiling whole potatoes but greater in oven baking in the peel or in boiling the peeled potato. Microwave cooking losses were less than in oven baking.     

Conjugated Linoleic Acid Content of Cheddar-type Cheeses as Affected by Processing

Samples were taken at 9 stages of processing, from raw milk to cheese aged for 6 mo. Fatty acid distributions, conjugated linoleic acid (CLA), moisture, protein, lipid contents, and titratable acidity were determined. CLA contents were highest after 3 mo, with one type of Cheddar (3.76 mg/g lipid) higher than the other two (3.44 and 3.47 mg/g lipid). Multiple linear regression showed all composition parameters were directly related to CLA content (mg/100 g sample). The content of oleic acid isomer C_18:1ω7 was also directly related to CLA content (mg/g lipid). Thus, content of CLA in Cheddar-type cheeses might be controlled by stage and conditions of processing. An understanding of the effects of processing on CLA formation in Cheddar-type cheeses will be beneficial in designing processing methods to enhance CLA contents.     

Retinyl Palmitate Isomers in Skim Milk During Light Storage as Affected by Ascorbic Acid

Effects of ascorbic acid addition on the contents of retinyl palmitate isomers in skim milk treated with or without 3 mg/mL added riboflavin were studied during storage for 30 h under fluorescent light. Light illumination induced the reduction of all-trans-retinyl palmitate and 13-cis isomer, but promoted the production of 9-cis isomer in the skim milk. Riboflavin increased the reduction of all-trans-retinyl palmitate, but decreased the formation of 9-cis isomer in lightstored skim milk. The addition of ascorbic acid greatly inhibited the light-induced reduction of all-trans-retinyl palmitate and 13-cis isomer in skim milks. Ascorbic acid also greatly increased the formation of 9-cis-retinyl palmitate in skim milks during light storage.     

Mechanical Properties and Chemical Composition of Peanuts as Affected by Harvest Date and Maturity

Harvest date and maturity (by the Hull Scrape method) were compared to mechanical properties and chemical composition of peanuts. In general, later-harvested or mature peanuts exhibited higher cutting and shear-compression forces, shear-compression energy and slope of force-deformation curve than earlier-harvested or immature peanuts. Mesocarp color of peanuts could be used as an index to group peanuts with similar shear-compression energy (sensory crunchiness). Harvest date did not affect dry basis chemical composition except carbohydrates content decreased slightly as digging was delayed. Oil content increased and carbohydrates decreased as peanuts matured. Total unsaturated fatty acids content increased with maturity.     

Changes in Grape Seed Phenols as Affected By Enzymic and Chemical Oxidation in vitro

An in vitro oxidation system containing all the phenolic compounds of an extract of grape seeds and phenol oxidases (catechol oxidase from grapes and laccase from grey mold of grape Botrytis cinerea) was used to determine the effects of enzymic oxidation on seven phenolic compounds: gallic acid, (+)-catechin; (-)-epicatechin and four procyanidins, dimers of (+)-catechin and (-)-epicatechin units. HPLC determinations showed that there was considerable depletion of phenolic compounds in the extract by both enzymes since the quantities of all the compounds fell during enzymic oxidation. When a pure chemical oxidation was compared, the decrease was very much slower.     

Influence of Potassium Fertilization on Enzymatic Activity, Phenolic Content and Discoloration of Potatoes

SUMMARY— Ontario potatoes, representing a variety that is very susceptible to precooking blackening, were grown in each of two consecutive years at different levels of potassium fertilization. In each of the two years of the study, the discoloration and total phenolic content of tubers decreased as potash applications were increased from 140 to 400 or 540 lb. per acre. The differences in discoloration were significant at the 1% level and the differences in phenolic content at the 5% level. Potatoes grown at high levels of potassium fertilization had higher cytochrome oxidase activity than those grown at lower levels. Potassium fertilization had no significant effect on polyphenol oxidase activity. A positive correlation (0.830) was found between the phenolic content and discoloration of potatoes as affected by potassium fertilizer.     

Cooking and Sensory Properties of Pork Crumbles as Affected by Pregelatinized Potato Starch, Crumble Diameter and Fat Content

Pork crumbles were processed at two fat levels (15, 40%) with or without addition of modified pregelatinized potato starch and into two sizes (0.95 cm, 1.90 cm diameters). Following precooking and reheating, large-diameter crumbles were softer and more juicy than small crumbles. Those with 40% fat were less firm and had lower precooking yields, but they still received high juiciness scores even when processed without modified pregelatinized potato starch. Potato starch provided improvements in precooking yields, and reduced fat retention during precooking and reheating.     

Chemical Forces,Structure, and Gelation Properties of Sweet Potato Protein as Affected by pH and High Hydrostatic Pressure

Sweet potato is one of cheap sources for starch industries worldwide, and exploiting starch wastewater as an alternative protein source is mainly environmental and economic concerns. In this study, the effects of high hydrostatic pressure (HHP; 250, 400, and 550 MPa) on chemical forces, structure, and gelation properties of sweet potato protein (SPP) at pH 3.0, 6.0, and 9.0 were investigated. The values of surface hydrophobicity (H_o) and absolute value of zeta potential of SPP significantly increased from 250 to 550 MPa (p?<?0.05) at all three pH conditions. The total amount of sulfhydryl (-SH-) groups in SPP decreased after HHP at pH 9.0, whereas the amount of free -SH- increased. High molecular mass aggregates (>?180 kDa) were observed in SPP after HHP at pH 6.0 and 9.0 by SDS-PAGE. Regarding elastic rheological behaviors, storage modulus (G′) values of SPP were significantly strengthened after HHP treatment. In addition, textural properties and water-holding capacity of gels made from SPP after 250 and 400 MPa at pH 9.0 were significantly improved, and the gels showed a compact and uniform gel network with the contribution of immobilized water fractions. The gel properties exhibited by SPP after HHP treatment at different pH levels, in particular after 400 MPa at pH 9.0, suggested that it could be potential protein resources as new gelling reagent in the food system.     

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.     

Inhibition of Papain in Meat by Potato Protein or Ascorbic Acid

Three methods (Warner-Bratzler shear, myofibril fragmentation index, and sensory panel evaluation) were used to determine effectiveness of ascorbic acid or potato inhibitor on papain activity in meat. Potato inhibitor at 0.6, 0.8, and 1.0 mg/mL did not sustain inhibition of papain activity in meat. While 2.5 × 10^--³M ascorbic acid inhibited papain in meat, this quantity of ascorbic acid induced off-flavor which was unacceptable to sensory panelists. A lower level of 2.5 × 10^--⁴ M would retard but not completely eliminate papain activity while producing more acceptable sensory results.     

Determination of Boza's Organic Acid Composition as it is Affected by Raw Material and Fermentation

In the current study boza, a low-alcohol-content beverage, is produced from rice, maize, millet and wheat flours by spontaneous fermentation at 24 ± 1°C for 24 h. During the fermentation and storage period, changes in total titritable acidity, pH, alcohol and organic acid profiles, and sensory properties were determined. The major organic acids were found as oxalic, lactic, pyruvic, and acetic acids. Even though the ratings of sensory parameters were not within wide limits, they were significantly affected by storage time. Maize boza scored higher due to the similarity in its colour and flavour to that sold in the market.     

叶菜型甘薯茎尖的氨基酸含量及组成分析

以叶菜型甘薯茎尖和21种常见蔬菜为材料,对比分析了氨基酸含量及组成.结果表明(1)甘薯茎尖含有18种氨基酸,种类齐全.其氨基酸总量、人体必需氨基酸含量和儿童必需氨基酸含量均居第1位.(2)甘薯茎尖的E/T值为39.50%,E/N值为0.65,符合理想蛋白质的要求.(3)甘薯茎尖中各种人体必需氨基酸,Val、Ile、Leu、Phe+Tyr、Lys、Thr的含量占氨基酸总量的比例,与1973年FAO/WHO修订的人体必需氨基酸含量模式谱基本一致,仅Met+Cys中度缺乏.(4)甘薯茎尖中鲜味类、芳香族、甜味类氨基酸含量居第1位.     

Chemical Composition,Amino Acid Content and Protein Quality of the Little-Known Legume Bauhinia purpurea L

Some nutritional and antinutritional characteristics and biological value of Bauhinia purpurea L seeds were studied. The mature seeds contained (g kg^-1 as is) 271·7 crude protein, 58·7 crude fibre, 124·5 crude fat, 29·3 ash and 515·3 carbohydrates. Potassium, phosphorus and iron occurred in higher concentrations when compared with commonly consumed legumes. The globulins and albumins together constituted major storage proteins (82% total protein). The essential amino acid profile of total seed proteins compared well with the FAO/WHO reference pattern except for a deficiency of sulphur-containing amino acids and tryptophan. When compared with the globulins, the albumins appeared to be a rich source of cystine, methionine, threonine, lysine and tryptophan. Seed lipids contained high levels of the unsaturated fatty acids, oleic and linoleic, which accounted for 62·6% of total fatty acids recovered. Both dry heating and autoclaving significantly reduced the antinutritional compounds. The in vitro protein digestibilities of raw, dry-heated and autoclaved seeds were 59·5, 72·3 and 78·7%, respectively. True digestibility and net protein utilisation were significantly higher in processed seed samples compared with raw seeds. Regarding utilisable protein, autoclaved samples exhibited relatively higher values than raw seeds. © 1997 SCI.