Isolation and characterization of functional components from peel samples of six potatoes varieties growing in Ontario

Potato processing industry generates high amounts of peel as a byproduct. It is a good source of several beneficial functional ingredients including antioxidant polyphenols. A study was undertaken to estimate the polyphenolic content and antioxidant properties of peel samples from potatoes grown in Ontario, Canada. Peel samples from Vivaldi, Yukon Gold, Dakota Pearl, FL 1533, Siècle and Purple Majesty varieties of potatoes were extracted with methanol and analyzed for their polyphenolic contents and antioxidant properties using Folin–Ciocalteu reagent, ferric-ion reducing antioxidant power (FRAP), Trolox equivalent (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) and free radical scavenging activity (FRSA). Specific phenolic compounds present in potato peel samples were measured using HPLC. Results of total phenolic compounds from both spectrophotometric and chromatographic analyses were statistically compared to validate methods of extraction and determination. Red-colored potato varieties; Siècle and Purple Majesty, had the highest antioxidant potential compared to other varieties. Chromatographic data showed differences in the amounts, but not in types of phenolic compounds in the potato peel samples.     

不同品种紫薯抗氧化物质及体外抗氧化活性比较

为比较福建产区主栽紫薯抗氧化物质成分含量及其体外抗氧化活性,对7个不同品种紫薯中总酚、总黄酮、总花色苷及花青素组分进行了分析,并测定其清除自由基活性。结果表明:福宁紫3号紫薯中所含抗氧化活性成分如总酚、总黄酮、总花色苷和花青素的含量均为最高。通过高效液相色谱法分析测定紫薯中含有的花青素单体主要为飞燕草色素、芍药色素和矢车菊色素,不同品种紫薯中花青素组成及含量表现出的一定的差异性。福宁紫3号紫薯表现出较强的自由基清除活性,0.5 mg·L-1紫薯鲜样提取液DPPH自由基、OH自由基及ABTS清除率分别达到88.4%、49.1%、90.1%。 相对于其他品种,福宁紫3号紫薯在抗氧化活性成分含量及体外抗氧化活性方面表现最佳。     

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.     

不同加工方式对紫色马铃薯中酚类物质的影响

紫色马铃薯富含花青素、绿原酸等多酚类物质,是价格低廉、取材广泛的天然抗氧化剂来源。为探明加工方式对紫色马铃薯中酚类物质的影响,最大程度地保留抗氧化活性物质,以3个紫色马铃薯品系和白色马铃薯品种‘夏波蒂’为实验材料,采用蒸制、微波和水煮3种加工方式进行处理,分析加工前后紫色马铃薯块茎中花青素、绿原酸、自由态多酚、结合态多酚的含量及抗氧化活性的变化。结果表明,3种加工方式均导致紫色马铃薯花青素含量的降低;与对照品种‘夏波蒂’相比,蒸制和微波处理后紫色品系马铃薯自由态多酚、结合态多酚、绿原酸的含量及抗氧化活性均更高,而水煮处理后,除结合态多酚的含量增加外,其余成分的含量均显著降低。因此,微波和蒸制加工可以更好地保留紫色马铃薯中的多酚类物质,从而发挥其抗氧化作用。     

Effects of preparation procedures,packaging and storage on nutrient retention in peeled potatoes

The effects of preparation procedures and packaging on vitamin C, dietary fibre, sugars, ash and moisture contents were studied in prepeeled packaged potatoes during two cultivation seasons. The potato cultivars Bintje, Van Gogh and Nicola were studied. Potatoes of the Nicola cultivar had the highest initial vitamin C and sugar contents. Retention of nutrient contents in packaged, prepeeled potatoes was very good after a 7-day storage period. Vitamin C contents were higher in packaged potatoes than in fresh tubers when ascorbic acid was used in the washing solution but the levels decreased during the 7-day storage period. When calcium chloride was added as well into the washing solution vitamin C contents remained high throughout the storage period. These results show that it is possible to preserve the nutritional contents of packaged potatoes over a 7-day storage period. Cooking decreased vitamin C contents by about 30% and keeping the potatoes hot for 1 h after cooking decreased vitamin C contents a further 10%. © 1998 SCI.     

Chlorogenic Acid and Other Phenolic Compounds in Fourteen Sweet Potato Cultivars

Fourteen cultivars of sweet potatoes were analyzed qualitatively for their phenolic content at harvest and after storage. The phenolic content of the sweet potato cultivars, Centennial, Jasper, Jewel, LO-323, L3-243, L3-151, L4-62, L4-112, L4-131, NC-702, NC-718, NC-719, NC-345, and V₂-237, was assayed. The qualitative examination of the sweet potato phenolics resulted in the separation and identification of four isomers of caffeolyquinic acid. A fifth compound, which exhibited phenolic acid characteristics, was separated but could not be identified.     

Microbial growth and the effects of mild acidification and preservatives in refrigerated sweet potato puree

Refrigerated sweet potato puree is a convenient form of sweet potato that can be used as an ingredient in formulated foods. The microbiology of refrigerated sweet potato puree during storage for up to 5 weeks was evaluated. Because the puree was made by comminuting steam-cooked sweet potatoes before refrigeration, no naturally occurring vegetative bacterial cells were detected during a 4-week period of refrigerated storage at 4 degrees C. However, if postprocessing microbial contamination of the puree were to occur, contaminating microorganisms such as Listeria monocytogenes could grow during refrigerated storage. The effects of acidification or the addition of potassium sorbate and sodium benzoate on a population of L. monocytogenes inoculated into refrigerated (4 degrees C) sweet potato puree were determined. Inoculation of the refrigerated puree with L. monocytogenes at 10(6) CFU/ml resulted in a 3-log increase after 3 weeks storage of nonsupplemented puree. Supplementation of the sweet potato puree with 0.06% (wt/vol) sorbic acid or benzoic acid plus mild acidification of the sweet potato puree with citric acid to pH 4.2 prevented growth of L. monocytogenes during storage at 4 degrees C.     

不同熟化方式对速冻熟紫薯品质的影响

为深入研究冻前不同熟化方式对速冻熟紫薯品质的影响,本实验以‘紫罗兰’紫薯为原料,采用蒸制、微波制和烤制3种熟化方式处理速冻熟紫薯,并对挥发性成分、色泽、微观结构、花色苷含量和抗氧化活性等进行分析。结果表明,不同熟化方式能够引起速冻熟紫薯中挥发性风味物质的重新分布,提供更多的芳香气味和独特的风味。熟化处理使速冻熟紫薯内组织结构发生变化,使其更易于消化,同时不同熟化处理紫薯花色苷含量也有显著差异,其中蒸制熟紫薯达4.12 mg/g,与鲜紫薯（3.36 mg/g）相比显著提高（P<0.05）。经液相色谱串联质谱（liquid chromatography tandem mass spectrometry,LC-MS/MS）分析鉴定出的紫薯花色苷共有六大类,主要是芍药色素和矢车菊素,蒸制熟紫薯中芍药花素占比最大,达到总量的84.12%,较好地保留了紫薯营养成分和色泽。此外,熟化处理还提高了速冻熟紫薯中花色苷在胃肠消化过程中的释放量,进而显著提高了其抗氧化活性（1,1-二苯基-2-三硝基苯肼自由基清除率、2,2-联氮基双(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基清除率和O2-·清除率）,...     

鲜切甘薯不同部位褐变机理差异

以‘渝薯17’甘薯为实验材料,将鲜切甘薯分为皮部、周边以及中心3 个部位。通过对冷藏过程中鲜切甘 薯不同部位褐变情况、褐变底物酚类物质含量、褐变相关酶活力的比较研究,探讨鲜切‘渝薯17’不同部位的褐变 机理及差异。结果表明,绿原酸是甘薯褐变的主要底物,鲜切甘薯不同部位褐变存在差异,皮部褐变最严重,周边 次之,中心最弱。皮部总酚和游离酚含量均显著高于周边和中心组织（P＜0.05）,其中主要底物绿原酸含量为周 边和中心组织的3～4 倍。多酚氧化酶（polyphenoloxidase,PPO）是引起皮部组织褐变的主要酶,苯丙氨酸解氨酶 对酚类物质的积累起促进作用;周边组织褐变由PPO和过氧化物酶（peroxidase,POD）协同作用催化;中心组织 褐变则主要由POD引起。     

The Effectiveness of Antibrowning Dip Treatments to Reduce After‐Cooking Darkening in Potatoes

Abstract: After‐cooking darkening (ACD) is an inherent and undesirable trait that develops in cooked potatoes. The objective of this study was to evaluate the effectiveness of sodium acid sulfate (SAS) dip treatments compared to other antigraying treatments and a control to reduce ACD in boiled, Katahdin potatoes. Dip treatments were applied for 3 min prior to boiling and included: 3% SAS, 3% citric acid (CA), 3% sodium acid pyrophosphate (SAPP), along with a distilled water control. SAS‐ and CA‐treated potatoes had slightly, but significantly (P ≤ 0.05) higher b* and chroma values, which indicates a more intense yellow potato color, with less graying, compared to the control. SAS‐ and CA‐treated potatoes also had significantly (P≤ 0.001) lower pH values for inner and outer potato surfaces than the control. No significant (P > 0.05) differences were detected for total phenolic or mineral contents among treatments. CA and SAPP samples had slightly, but significantly (P≤ 0.05) higher moisture contents than the control. Sensory test results showed no significant differences for color, aftertaste, or overall acceptability. However, CA‐treated samples were rated significantly (P≤ 0.05) lower for flavor than all other treatments and panelists commented on sour notes. CA‐ and SAS‐treated potatoes were scored slightly, but significantly lower for texture than other treatments due to a waxy outer layer. However, SAS was the most acidic dip treatment, but did not significantly affect flavor. Overall, results suggest that SAS was similarly accepted by consumers in comparison to CA and SAPP, which is the industry standard to reduce ACD. Practical Application: After‐cooking darkening (ACD) is an undesirable potato trait that occurs after potatoes have been processed. Sodium acid pyrophosphate (SAPP) has been used as the industry standard to reduce ACD. Sodium acid sulfate (SAS) treatments prior to boiling appeared to be comparable to SAPP and citric acid in effectiveness to reduce ACD. SAS did not negatively affect the flavor of boiled potato samples according to sensory results. The SAS treatment may be more beneficial for potatoes intended for potato salad products.     

Acrylamide content in fried chips prepared from irradiated and non-irradiated stored potatoes

The content of reducing sugars and asparagine, responsible for the formation of acrylamide, was determined in eight Indian potato varieties. Among these, Kufri chipsona-2 and Kufri lavkar showed the lowest level of reducing sugar (680.68 ± 56.50 mg/kg) and asparagine (2074.36 ± 122.27 mg/kg), respectively. The acrylamide content in potato chips prepared from Kufri chipsona-2, the variety that is used commercially in India for making potato chips was also the lowest. Irradiation of this variety of potatoes at the sprout inhibition dose of 60 Gy and subsequent storage for six months showed a 10.7% lower content of reducing sugars at both 14 and 4 °C. The acrylamide content was 8.41% and 6.95% lower in chips from irradiated potatoes stored at 14 and 4 °C than the corresponding non-irradiated controls. The colour of the chips was also better in irradiated potatoes as judged from the L∗ and a∗ values.     

Effect of irradiation on vitamin C content of strawberries and potatoes in combination with storage and with further cooking in potatoes

The vitamin C content of four varieties of strawberry was determined before and after treatment with ionising radiation at doses of 1, 2 or 3 kGy and after storage for 5 and 10 days at 6°C, and also in potatoes which, having been allowed a period of one month to recover from the effects of post-harvest stress, were irradiated at a sprout inhibition dose of 0·15 kGy, followed by storage and cooking. Total ascorbic acid (TAA), ascorbic acid (AA) and dehydroascorbic acid (DHAA) concentrations were measured using the technique of ion-exclusion high-performance liquid chromatography. Results from analysis of the strawberry samples showed the DHAA content increased immediately following irradiation and must, therefore, be taken into account when reporting vitamin C levels in irradiated produce. In addition it was observed that whilst irradiation did affect the vitamin C concentration in all varieties of strawberry, the change was small in comparison with the large variations observed between varieties. With regard to potatoes results showed that, whilst irradiation, storage and cooking all had the effect of reducing vitamin C concentration, irradiated samples stored for 5 months had similar or marginally higher levels than their non-irradiated counterparts. Cooking did not markedly reduce TAA content of irradiated potatoes compared to non-irradiated potatoes and it was also noted that microwave cooking was more destructive than boiling in lightly salted water. ©1997 SCI     

温州蜜柑、椪柑采后酚类物质及抗氧化活性比较研究

通过研究温州蜜蜂柑、椪柑两个常见柑橘品种贮藏期间类黄酮、酚酸类物质及抗氧化活性的变化规律,评价其采后的营养品质。结果表明：贮藏60d后温州蜜柑较好地保持了抗坏血酸含量,而椪柑损失较大。类黄酮类物质较稳定,温州蜜柑中黄烷酮含量贮藏后有所增加,椪柑中则呈缓慢下降趋势,2种柑橘中酚酸类物质贮藏后都有所增加。总酚含量在贮藏前期呈下降趋势,贮藏后期温州蜜柑中总酚含量增加而在椪柑中进一步下降。抗氧化能力与抗坏血酸的变化趋势类似。与椪柑相比,贮藏期间温州蜜柑能更好地保持果实的营养品质及酚类物质,从而保持较高的抗氧化活性。     

Charakteristik der Stärke ausgewählter Kartoffelsorten Teil 1. Änderung des Stärkegehalts und der Stärkekorngröße während der Lagerung

Characteristics of Starch of Selected Potato Varieties. Part 1. Change of Starch Content and Starch Granule Size During Storage . Selected varieties of potatoes of the Czechoslovakian assortment were tested as to their contents of dry matter and starch, as well as to quality of their starch in three-years storage tests. Potatoes were stored in airconditioned boxes at temperatures of + 2 and + 10 °C. Analyses were carried out after harvesting and after storage. It was found that the content of dry matter was higher near the end of storage time. This increase was depending on temperature. Yet, related to dry matter the starch content had not diminished near the end of storage time. During storage of potatoes changes in the share of individual starch granule sizes do also occur. Larger granules were degraded to smaller ones, thereby increasing the latter's share. Higher temperature would also lead to an increase in these changes. The tests were supposed to show, wether during potato storage a change in size of starch granules takes place, and wether storage temperature may influence this change. Work on this problem will be continued.     

Comparative study of crude and refined kenaf (<Emphasis Type="Italic">Hibiscus cannabinus</Emphasis> L.) seed oil during accelerated storage

This study assessed the changes of antioxidant activity and bioactive compounds of crude and refined kenaf seed oil during accelerated storage at 65°C for 24 days. 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were used to determine their antioxidant activity. The changes of phenolic, tocopherol, and phytosterol contents during the storage were also studied. The phenolic content and antioxidant activity of refined oil were significantly lower than those of crude oil after the accelerated storage. There was a decrease of 72.5% tocopherol content and 31.1% phytosterol content in the crude oil and a decrease of 67% tocopherol content and 12.1% phytosterol content in the refined oil during the accelerated storage. There was no significant difference in tocopherol and phytosterol contents for crude and refined oils after the storage. The rate of degradation of tocopherol and phytosterol contents in refined oil was slower than that in crude oil during the storage.     

Effect of γ-irradiation on phenolic compounds in rice grain

Whole grain rice is rich in phenolic compounds. The effect of γ-irradiation on the main phenolic compounds in the rice grains of three genotypes (black, red, and white) was investigated. Three phenolic acids (p-coumaric acid, ferulic acid, and sinapinic acid) were identified as major phenolic compounds in all rice samples, while two anthocyanins (cyanidin-3-glucoside and peonidin-3-glucoside) were identified in pigmented grain samples. In general, γ-irradiation at most of doses could significantly (p < 0.05) decrease total phenolic acid contents in all samples and total anthocyanins contents in the black rice, but their decreases were not completely in a dose-dependent manner. Unexpectedly, 6 and 8 kGy significantly (p < 0.05) increased total contents of anthocyanins and phenolic acids in black rice. This study suggested that suitable doses of irradiation might be carefully selected and used to minimise the loss of antioxidant phenolic compounds in whole grain rice during storage.     

Experiences of food irradiation in Japan

Abstract

In this paper, we shall attempt to present the history and current status of food irradiation research and commercialization in Japan. In 1967 the Japan Atomic Energy Commission decided to promote the research and development of food irradiation, based on research activities since 1954. The national project on food irradiation investigated the following: 1) the inhibition of sprout growth of potatoes and onions, 2) the prevention of infestation of rice and wheat, 3) the extension of shelf life of sausage and fish‐paste products, and 4) the growth inhibition of molds on the surfaces of oranges by using electron beams. As a result of this national project, a commercial potato irradiation plant was constructed and has been operating for 12 years. Market price fluctuations during the off‐season were also successfully reduced. However, a boycott movement by some consumer unions against irradiated potatoes has seriously affected food processors. The technical problems of irradiated potatoes, such as rotting and accumulation of sugar during storage, were solved by conditioning before and after irradiation. After the termination of the national project, studies were carried out on farm animal feeds for the purpose of eliminating pathogens such as salmonellae and extending shelf life by delaying mold growth. The accumulation of sugar in irradiated sweet potatoes, identification methodology of irradiated foods, and radiation‐decontamination of microorganisms in spices have also been studied. The greatest problem now is to overcome the public's resistance to irradiated food.     

有效去除马铃薯中龙葵素方法的探究

目的探究一种日常生活中简单有效去除马铃薯中龙葵素的方法。方法对马铃薯进行分组贮藏实验,通过不同预处理方法(如去芽孔径大小、不同加工形状、不同浓度食醋水溶液或柠檬酸水溶液浸泡等)处理后采用液相色谱串联质谱法测定龙葵素含量,研究龙葵素含量的变化情况。结果对于轻微发绿或发芽马铃薯,可以进行削皮、去芽处理后,进行水浸、食醋水溶液浸、柠檬酸水溶液浸处理5～15 min,均可降低马铃薯中约70%～80%龙葵素。结论此方法实用性和可操作性强,可有效预防家庭、餐馆以及食堂等龙葵素中毒事件发生,对保障人民食品安全具有重要意义。     

EFFECT OF PACKAGING MATERIAL ON THE QUALITY OF POTATOES TREATED WITH ISOPROPYL N-(3-CHLOROPHENYL) CARBAMATE (CIPC)

Katahdin and Russet Burbank potatoes, treated with isopropyl N-3(-chlorophenl) carbamate CIPC and stored for four months at 5C in either mesh or polyethylene bags (two packaging materials frequently used for potato storage), were tested for enzymatic discoloration, phenolic and ascorbic acid concentration. CIPC residues in tubers stored in polyethylene bags were significantly (p < 0.0l) higher than those stored in mesh bags. Tubers stored in polyethylene showed significantly (p<0.05) higher discoloration and phenolic concentration, and lower ascorbic acid concentration than those stored in mesh bags. Differences in CIPC retention of the tubers stored in the two packaging materials may have been responsible for some of the differences in quality factors since CIPC was shown to significantly (p<0.0l) increase the enzymatic discoloration and phenolic concentration, and decrease the ascorbic acid concentration of both cultivars.     

The effects of radiation and extended storage on the chemical quality of garlic bulbs

Several chemical parameters were investigated in ‘red’ variety garlic, irradiated to inhibit sprouting, with doses of 30 Gy and kept under warehouse conditions. The studies were conducted between 210 and 270 days post harvest (critical marketing periods) when this variety was not normally available for raw consumption.It was found that, during storage, the irradiated garlic showed a significant increase in ascorbic acid content but no change in dry matter content compared with non-irradiated garlic. Compared with non-irradiated garlic, at 270 days' storage, the irradiated garlic had a higher index of flavour, measured as enzymatic pyruvate, a higher acidity and a lower content of water-soluble carbohydrates.From these observations, the irradiated garlic should be suitable for prolonged storage with the object of marketing it during critical periods.