Altering pasting characteristics of sweet potato starches through amino acid additives

ABSTRACT:  This study assessed the effects of amino acid additives, aspartic acid, leucine, lysine, and methionine, on the pasting and thermal characteristics of white- and orange-fleshed Beauregard sweet potato starches. A rapid visco analyzer 3D was used to determine pasting properties. In comparing pasting characteristics, starch from orange-fleshed sweet potato was found to be easier to cook, had a lower potential for retrogradation, and was less stable during heating than the white-fleshed sweet potato starch. The RVA analysis showed that the charged amino acids, aspartic acid and lysine, altered pasting characteristics of the 2 starches more than the neutral amino acids, leucine and methionine. Aspartic acid had similar effects on both starches, making them less stable during cooking and lowering the potential for retrogradation. Lysine, when added to the orange-fleshed sweet potato starch, decreased the breakdown, allowing for more stability during cooking. This study showed that pasting properties of sweet potato starches can be altered by the addition of amino acids.     

Physiological behavior and quality traits during fruit growth and ripening of four Amazonic hot pepper accessions

BACKGROUND: Skin color, acid content and changes in other chemical components have been developed as indicators of maturation in fruits of the Capsicum type. RESULTS: Fruit growth and ripening in four hot pepper accessions (CS) from C. frutescens (CS376) and from C. annuum (CS219, CS049 and CS032) were monitored in three commercial Colombian Amazonic orchards. The time between fruit setting and commercial pepper fruit maturity was 41 ± 5 days for CS219, while CS032, CS049 and CS376 required 47 ± 3 days. Three stages of development were identified. The first stage was cell division in the accessions and a transient peak in respiration rate in CS049. A second stage of fruit growth occurred due to maximum cell expansion and some transient peaks of respiration rate also took place. Finally, a plateau occurred as fruit reached full maturity and followed typical non‐climacteric behavior. CS032 and CS219 were pungent with increasing levels of alkaloids (capsaicin and dihydrocapsaicin) during fruit growth, although CS376 with its constant and higher levels of the former capsaicinoids early in fruit growth was not pungent, and neither was CS049. Morphological traits and fresh and dry weight together with color coordinates could be used to discriminate among accessions as revealed by two axes of the canonical discriminant analysis (99.9% total variance explained). CONCLUSIONS: In general, the time from fruit set and the apex skin color changes and accompanying morphological traits, were reasonable indicators of maturity in Amazonian hot pepper fruits. Multivariate analysis was able to discriminate among accessions. Copyright © 2008 Society of Chemical Industry     

Comparative potential of white and red clover to modify the milk fatty acid profile of cows fed ryegrass‐based diets from zero‐grazing and silage systems

BACKGROUND: Two experiments were conducted to compare the effects of white and red clover on the fatty acid composition of milk fat from cows fed ryegrass‐based diets. In experiment 1, fresh ryegrass was mixed with white or red clover (60/40, on a dry matter (DM) basis). Experiment 2 involved similar mixed diets in ensiled form, and one ryegrass‐silage diet without the addition of clover. RESULTS: Total DM intake, milk yield and milk fat content were not affected by dietary treatments. Feeding freshly cut white versus red clover supplemented diets resulted in a higher proportion of n‐3 fatty acids, especially α‐linolenic acid, in milk fat. Addition of any clover silage to ryegrass silage increased the proportions of n‐3 fatty acids in milk fat, and reduced the proportions of conjugated linoleic acids (CLA), including C18:2 c9t11, and C18:1cis isomers. The n‐6/n‐3 ratio was elevated compared to the diet not supplemented with clover. CONCLUSION: White clover seemed to be slightly superior to red clover supplementation, but the effects of clover supplementation as such were generally larger than that of clover type. However, a higher concentration of n‐3 fatty acids with clover supplementation coincided with a lower concentration of CLA in the milk fat. Copyright © 2007 Society of Chemical Industry     

Basis for the new challenges of growing broccoli for health in hydroponics

BACKGROUND: Variations in the contents of phytochemicals with biological activity in broccoli could originate as a result of genetic and environmental factors. An understanding of the effects of growth conditions on the bioactive compounds in broccoli is essential for improving its quality and nutritive value. Using salinity (40 mmol L^?1 NaCl), and foliar sprayed compounds (methionine, tryptophan and chitosan) as different stress conditions, broccoli developed in soilless culture in the greenhouse was analysed for biologically active phytochemicals (glucosinolates, caffeoyl‐quinic, ferulic and sinapic derivatives and vitamin C). RESULTS: The application of elicitors during head formation could be beneficial for the enrichment in phytochemicals in broccoli. Management practices for increasing a given phytochemical (e.g., glucoraphanin or glucobrassicin) may be related to a decreased level of natural antioxidants (hydroxycinnamic acids). Growing broccoli hydroponically in the greenhouse in winter (Mediterranean climate) needs the supporting treatment of abiotic stress during development (i.e., NaCl, elicitors). CONCLUSION: The use of hydroponic growth conditions for broccoli and the application of stress factors (elicitors) at head induction and during development may serve the purpose of enhancing its nutritional quality to deliver a health‐promoting food. Copyright © 2008 Society of Chemical Industry     

Effects of phenolic acids and transglutaminase on soft wheat flour dough and baked products

BACKGROUND: The effects of phenolic acids on the physical properties of soft wheat flour dough and baked soft wheat flour products were investigated. Transglutaminase (TG) was added to observe the effects of non‐disulfide crosslinks on phenolic acid treated dough. Ferulic acid, p‐coumaric acid or fumaric acid was blended with pastry flour at a level of 250, 500 or 1000 ppm of flour dry weight, respectively. RESULTS: The addition of phenolic acids, TG or a mixture of phenolic acids and TG to flour had no effect on the mixing properties of the doughs but significantly affected 90 min rested dough. The addition of phenolic acids decreased the maximum resistance and increased the extensibility of 90 min rested dough, and TG reversed the effects of phenolic acids on the rested dough. The physical characteristics of cookies blended with each phenolic acid plus TG were not significantly different (P > 0.01) from those of the control cookies. However, TG with and without phenolic acids had significant effects on the moisture content, weight and volume of crackers. CONCLUSION: These results suggest that the addition of phenolic acids and TG in the absence of a fermentation process do not affect the physical properties of soft wheat flour products. The fermentation process allows the chemical reaction of the phenolic acids and TG to occur before the soft wheat flour products are baked. Copyright © 2008 Society of Chemical Industry     

Phenolic constituents levels in cv. Agria potato under microwave processing

Phenolic compounds have long been associated with flavour and colour characteristics of fruits and vegetables and actually attract a great interest due to their health protecting properties. In this work, the influence of different power input of microwave baking on the amount of protocatechuic acid (1), tryptophan (2), chlorogenic acid (3), neo-chlorogenic acid (4), and cryptochlorogenic acid (5) marker compounds left over in peeled and not-peeled potatoes (Solanum tuberosus L., Agria cultivar) was assessed. A high-performance liquid chromatographic (HPLC) method with diode-array detection (DAD) was used to identify and quantify compounds 1-5. Other tubers were used to perform analysis of raw potato (control) and traditional baking potatoes products (boiled potatoes). Dielectric behavior of the irradiated tubers was also investigated to emphasize if microwaves treatments are suitable for food processing in terms of nutritional factor preservation. The main results of this work consist on the relevance of the water contents in potato matrixes during the baking processes since these have a crucial role to keep lossy features, to avoid thermal damages and to preserve antioxidant. The best compromise in terms of short baking time and reduced water and phenolic losses is obtained using 500 W as power input.     

The Effect of Hydroxycinnamic Acids and Volatile Phenols on Beer Quality

To the consumer, beer should be an agreeable beverage of attractive colour, clarity, pleasing flavour and should carry no toxic substances. One of the major constituents of barley is phenolic acids and their direct effect on the quality of beer is still a mystery. The aim of the study therefore was to investigate the relationship between phenolic acids during mashing at different temperatures and the quality of the beer. The mash regime and liquor to malt ratios were optimised and the carbohydrates obtained were analysed at 3.5 L of water per kg of malt and a total mash time of 105 min. Carbohydrate and phenolic acid analyses were performed by HPLC coupled with a UV‐vis detector. The three different malts used had a phenolic acid content of 33.25 μg/mL, 25.44 μg/mL and 19.98 μg/mL for malt A, B and C, respectively. The plot of 1/T versus Ln(t) gave a negative slope with activation energy (E_a) = 209 KJ/mol, rate constant (k) = 4.6 × 10^?4 mg/L min, which are comparable to similar data reported in the literature. The kinetics studies showed that the optimised mashing temperature of 90°C was adequate to form 4‐vinylguaiacol by thermal decarboxylation from the hydroxycinnamic acids. This study has shown that there is no direct correlation between phenolic acids and oxidative flavour stability of beer while the corresponding volatile phenols may affect beer flavour.     

直链淀粉含量对大鼠肠道发酵产物的影响

目的:研究了不同直链淀粉含量的玉米淀粉对大鼠肠道发酵产物的影响.方法:将42只Wistar成年雌鼠随机分为7组,分别饲喂直链淀粉(AS)含量为0%、26.8%、53.8%、61.6%、75.7%、78.9%、85.8%的玉米淀粉饲料.喂养3周后解剖,测定各组体重、饲料效率及淀粉消化率、小肠内容物、盲肠内容物、盲肠组织重量以及盲肠中短链脂肪酸(SCFA)等指标.结果:61.6%AS、75.7%AS、78.9%AS和85.8%AS饲料组的淀粉表观消化率明显低于0%AS和26.8%AS饲料组.与0%AS和26.8%AS相比,高直链淀粉显著地增加了小肠内容物、盲肠内容物干重,75.7%AS组的盲肠内容物干重最高.高直链淀粉组盲肠中乙酸、丙酸和总SCFA的总量显著高于0%AS和26.8%AS组,53.8%AS组丙酸产量最高,61.6%AS组有最高丁酸和总SCFA产量,而75.7%AS有最高的乙酸、乳酸和琥珀酸产量,在高直链玉米淀粉中,78.9%AS组SCFA产量最低.结论:增加玉米淀粉中直链淀粉含量能明显降低淀粉的消化性,增加大鼠肠道中未消化残渣的量和盲肠中SCFA产量,但这种效果与直链淀粉的含量并没有明显的相关性.     

部分哺乳动物和鱼类胶原蛋白中氨基酸的组成和含量的比较

采用日立L-8800型氨基酸自动分析仪分析了部分哺乳动物e和e各氨基酸含量的差异为胶原蛋白的合理开发应用提供参考。结果表明各样品中均含有18种氨基酸,其中必需和半必需氨基酸有8种,但苏氨酸(Thr)、蛋氨酸(Met)和羟脯氨酸(Hyp)含量有明显差别。     

八角籽仁油GC-MS分析和急性毒性试验

以石油醚为溶剂提取八角籽仁油,通过GC—MS分析了八角籽仁油中脂肪酸的组成及含量,并对八角籽仁油进行了急性毒性试验。结果表明,八角籽仁油中亚油酸含量34．658％,油酸含量34．986％,棕榈酸含量17．838％,山嵛酸含量4．096％,硬脂酸含量4．093％,花生酸含量1．550％,二十四碳酸含量1．336％;不饱和脂肪酸占69．644％,饱和脂肪酸占28．913％。急性毒性试验初步确定八角籽仁油小鼠最小致死量和最大耐受量均大于40mL/kg。