Effect of Acetylation on Composition of Phenolic Acids and Proteolysis of Rapeseed Flour

Rapeseed flour was treated with various levels of acetic anhydride to produce flours with 35, 70, and 90% of the ε-amino groups of lysine acetylated. With the extent of acetylation, free phenolic acids ranged from 86 to 35 mg/100g, phenolic acids from hydrolyzed esters ranged from 1.51 to 340 mg/100g, and no insoluble-bound phenolic acid was found. With the extent of acetylation, an increase in rapeseed flour was less susceptible to tryptic and peptic hydrolysis and an increament of water- soluble protein fragments corresponding to molecular weights of 3700–4500 and 1600–2100 daltons was observed. However, these peptides were devoid of phenolic constituents. Acetylated rapeseed flours were less susceptible to tryptic and peptic hydrolysis.     

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 Magnesium Fertilizers on Total Glycoalkaloids and Nitrate-N in Katahdin Tubers

The effect of two sources of magnesium fertilization (56 kg/ha, MgO). ensom salt and dolomite. on total alvcoalkaloid (TGA) and nitrate-nitrogen (N0₃-N) content of Katahdin potatoes was examined. Both magnesium fertilizers increased the TGA and NOJ-N content of tubers. Tubers grown in soils receiving epsom salt had significantly (p < 0.05) higher TGA content than the tubers receiving dolomite immediately following harvest, but after 5 mo storage, no significant differences were observed between the two Mg sources. The NO₃-N levels in tubers from plants receiving Mg fertilization were higher than the controls. Those receiving epsom salt were higher than those receiving dolomite. The N03-N levels decreased in all tubers after 5 mo storage. Cortex tissue was significantly (p < 0.05) higher in N03-N than the pith.     

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%).     

Chitosan Coating Effect on Storability and Quality of Fresh Strawberries

The effect of chitosan coating (1.0 and 1.5% w/v) in controlling decay of strawberries at 13°C was investigated as compared to a fungicide, iprodione (Rovral®). Chitosan coating significantly reduced decay of berries (P ≤ 0.05) compared to the control. There was no significant difference between chitosan and fungicide treatments up to 21 days storage. Thereafter, Rovral®-treated berries decayed at a higher rate than chitosan-coated berries. Chitosan-coated berries stored at 4°C were firmer, higher in titratable acidity, and synthesized anthocyanin at a slower rate than Rovral®-treated or nontreated berries. Chitosan coating decreased respiration rate of the berries with a greater effect at higher concentration.     

Determination of Total Glycoalkaloids (TGA) in Dehydrated Potatoes

A method was developed to optimize TGA extraction for dehydrated potato products. Maximum TGA content was obtained from uncooked dehydrated powder with hydration ratio (powder:water) of 1:4 (by weight) for the freshly prepared powder. Powders prepared from precooked potatoes required a hydration ratio (1:5) for optimum TGA extraction. For powders that were stored for 4 months, 1 hr of hydration was necessary for maximum TGA extraction. In all varieties tested the TGA content of powders was slightly less than the fresh tissue but these differences were not statistically significant. However, significant varietal differences were observed. The Chipbelle and Katahdin varieties were significantly higher in TGA content than Rosa and Pontiac varieties.     

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 Sprout Inhibitor Isopropyl-N(3=Chlorophenyl)-Carbamate on Total Glycoalkaloid Content of Potatoes

The effect of the sprout inhibitor, isopropyl-N-(3-chlorophenyl)-carbamate (CIPC) on total glycoalkaloid (TGA) content of potatoes was investigated. Katahdin and Chipbelle potatoes grown at Cornell Research Farms, Freeville, NY and Riverhead, NY, were used. Potatoes treated with CIPC were significantly (p < 0.05) lower in TGA content than the controls. Potatoes stored at 25°C were significantly (p < 0.05) higher in TGA content than those stored at 5°C and TGA content increased significantly (p < 0.05) with increasing storage time.