IMMUNOCHEMICAL STUDIES ON THE NITROGENOUS CONSTITUENTS OF BEER FOAM*

Samples of foam prepared by two different procedures were analysed using immunoelectrophoretic methods with anti-barley and anti-chill haze immune sera and their constituents were compared to those of beer (total and defoamed) and of chill-haze. Two, and probably three, constituents reacting with the immune sera have been detected in both foam preparations and it was shown that at least two of the constituents are identical with the main nitrogenous components of chill-haze. Defoamed beer contains the same substances but at a low concentration when compared on the basis of weights of dry matter. These observations may have some practical applications.     

PATATIN AND ESTERASE IN DESIREE POTATO TUBERS1

Patatin, the major glycoprotein of potato tubers, had very similar chemical and physical properties whether isolated from cultivar Desiree or from Kennebec. The patatin of each cultivar exhibited copurification with p-nitrophenyl laurate esterase. However, the esterases from the two sources differed in substrate preference ranging from near equality toward α-naphthyl laurate to a hundredfold difference toward p-nitrophenyl laurate.     

EFFECT OF PROCESSING ON AMYLASE AND PROTEASE INHIBITOR ACTIVITY IN TROPICAL TUBERS

The effect of various processing methods on amylase, trypsin and chymo-trypsin inhibitory activities in tubers of Colocasia esculenta (taro), Xanthosoma sagittifolium (tannia), Solenostemon rotundifolius (Coleus, Chinese potato), Dioscorea esculenta (lesser yam) and Amorphophallus paeoniifolius (elephant foot yam) was studied. Among the different methods, frying was the most effective method of eliminating enzyme inhibitors from tubers. When cooked by boiling, partial retention (30 to 60%) of enzyme inhibitory activity was observed in certain tubers. Further reduction in inhibitory activity was observed in baked/pressure cooked tubers. The study indicated that processing decreased the inhibitor content significantly and the reduction of inhibitory activity was brought about by heat inactivation.     

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.     

INFLUENCE OF TEMPORARY ANOXIA BY SUBMERGING IN WATER ON LIGHT-INDUCED GREENING AND GLYCOALKALOID FORMATION OF POTATO TUBERS

Temporary anoxia created by submerging potato tubers in water completely inhibited light-induced greening and glycoalkaloid formation of Russet Burbank, White Rose and Pontiac cultivar. Preanoxia vacuum treatment of the tuber has the same effect but hastened rottenness of the tubers. Anoxia treatment also inhibited the respiration of potato tissue. Partial exposure of the surface of anoxia tubers to air reduced the inhibition. The inhibition of the light-induced greening by anoxia condition was due to inhibition of tuber respiration. The light absorption by the water used to create anoxia condition did not contribute to the inhibition of light-induced greening. The duration which tubers could tolerate anoxia condition depended upon the cultivar and the physical condition of the tubers. Incorporation of 100 to 1000 ppm sodium hypochlorite or daily replacing with fresh water effectively improved incubation stability and reduced rottenness.     

ULTRASTRUCTURAL LOCALIZATION OF SOLANIDINE IN POTATO TUBERS1

Microscopic and ultrastructural cytochemical techniques were utilized in an attempt to localize the site of solanine synthesis in potato (Solarium tuberosum L. cv Russett Burbank) tubers. Application of an alkaloid extract of potato tissues to TLC plates before and after incubating with digitonin indicated solanidine, a direct precursor in the biosynthesis of solanine, was removed by digitonin. In the electron micrographs, the solanidine-digitonin complex was recognized as darkly stained needles or spicules. These spicules were observed primarily in the vacuoles of sprouted tips with a few also noted in the cytoplasm and peridermal tissue. This study demonstrated only minute quantities of solanidine present. The small quantities observed may reflect a rapid conversion of solanidine to solanine or chaconine or insensitivity of the method.     

LACK OF CORRELATION BETWEEN TISSUE NECROSIS AND PHYTOALEXIN ACCUMULATION IN TUBERS OF POTATO CULTIVARS

Tuber disks of five potato cultivars, each compatible to the fungus race used, were treated with cell-free homogenate or lipophilic material obtained from the mycelial mat of Phytophthora infestans. On the effect of treatments, the various cultivars reacted in different manners as regards tissue necrotization and accumulation of phytoalexins rishitin, lubimin and phytuberin. No correlation was found between the extent of tissue necrosis and the level of phytoalexins. Each potato cultivar had a capacity for producing sesquiterpene phytoalexins even if the visible hypersensitive response (tissue necrosis) did not occur. It was concluded that there are compounds of pathogenic origin that induce phytoalexin accumulation as well as necrotization in plant tissues. The expression of necrotization mainly depends on different sensitivity of potato cultivars to treatments. The rate of phytoalexin accumulation would represent a potential for general resistance.     

不同溶剂和超滤浓缩倍率对甘薯蛋白提取及纯度的影响

探索了不同的提取溶剂和超滤对甘薯蛋白提取的效果。结果表明：与NaCl溶液和氢氧化钠溶液相比,蒸馏水更适合提取甘薯蛋白。超滤浓缩倍率与浓缩液中蛋白含量和制得蛋白粉纯度呈线性正相关（p≤0.01）。     

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.     

EFFECT OF MECHANICAL TREATMENT ON THE HARDNESS OF MARGARINE AND BUTTER

The work-softening of margarine and butter resulting from passage through perforated plates was determined. Various plates were used differing in size and number of perforations, but identical in the total area of perforations. Greater work-softening was obtained with plates having many small perforations, but the back-pressure in the equipment was higher. Passing the product through two or three plates slightly increased work softening. Additional mechanical action was provided by a propeller rotating immediately behind the perforated plates. Only small additional work-softening was obtained by this action and little remained after 8 days storage. Increasing the speed of the propeller up to 100 r.p.m. increased work softening. Increasing it to 300 r.p.m. did not further increase work softening. It appears that excessive mechanical action has little permanent softening effect on plastic fats.     

EFFECT OF SONIC ENERGY ON THE AIR DRYING OF APPLE AND SWEET POTATO CUBES

Cubes (2 cc) of apple and sweet potato were dried with and without sound energy in air at velocities of 5 – 20 fps and temperatures of 125 – 175°F. A stem jet or electronic whistle provided sound energy at 9,800 and 13,000 Hz with an intensity up to 135 dB. Results indicated that sonic energy had no effect on drying rate under all experimental conditions.     

CHANGES IN THE LOW MOLECULAR WEIGHT NITROGENOUS COMPOUNDS OF EXCISED BOVINE MUSCLE

Investigations were completed to determine whether any differences could be detected in the low molecular weight nitrogenous compounds of excised bovine muscle at O-time or that held at 4° C for 12 days. No differences were noted between the electrophoretic patterns of the soluble proteins of the 0 and 12day samples either before or after gel filtration on Sephadex G-25 columns. However, gel electrophoretic patterns indicated that one band consisted of low molecular weight non-protein compounds. Absorbance data (280 and 260 nm) of the soluble proteins separated by gel filtration indicated that the 12day sample contained a slightly higher level of low molecular weight nonprotein nitrogenous compounds than did the O-day sample. Results of nitrogen determinations of the gel-filtered extracts also supported this finding. Data of ultraviolet scanning of gel-ftltered extracts showed that the low molecular weight nitrogenous compounds had a greater absorbancy at 260 than at 280 nm. Results of two-dimensional paper chromatography-high voltage electrophoresis did not reveal the presence of polypeptides in either the O- or 12day samples.     

苯乙烯-马来酸酐(SMA)共聚物对颜料的分散及其在喷墨印花中的应用

介绍了苯乙烯-马来酸酐（SMA）共聚物的合成方法和分散性能。探讨了它对颜料分散的机理、影响分散性能的主要因素，以及在喷墨印花中的应用前景作了展望。