Characterization of several hazelnut (Corylus avellana L.) cultivars based in chemical, fatty acid and sterol composition

Nineteen cultivars of hazelnuts (Corylus avellana L.) collected during the 2001 crop, from Vila Real, Portugal, were analysed for chemical composition, including moisture, total oil content, crude protein, ash, carbohydrates and nutritional value. Fat was the predominant component, ranging from 59.3 to 69.0%. Total oil was extracted and analysed for fatty acid and sterol compositions and oxidative stability. Fatty acid and sterol compositions were determined by Gas–Liquid Chromatography coupled to a Flame Ionisation Detector (GLC/FID). Monounsaturated fatty acids, particularly oleic acid, were predominant (78.7–84.6%). Total phytosterol content ranged from 133.8 to 263.0 mg/100 g of oil. Among the nine sterols identified and quantified, β-sitosterol was the major one with a mean percentage of 83.6%, while Δ⁵-avenasterol and campesterol were the second and the third components of the group with mean values of 6.1 and 5.8%, respectively. Since hazelnut oil can be used in olive oil adulteration, the values obtained were compared with published mean values of olive oils from different geographical origins.     

干燥方式和贮藏对甘薯可溶性糖组分组成和变化的影响

目的 探究不同干燥方式和贮藏时期对甘薯可溶性糖分组成及其变化的影响。方法 以食用型甘薯烟薯25号和普薯32号为试验材料,按不同贮藏时期取样,分别进行冷冻干燥和热风干燥处理,采用超声振荡提取-离子色谱-脉冲积分安培法对样品中10种可溶性糖组分进行提取和同时测定。结果 冷冻干燥处理,烟薯25号和普薯32号甘薯中均检出大量的葡萄糖、果糖、蔗糖和少量麦芽糖、鼠李糖、阿拉伯糖、甘露糖、半乳糖,其可溶性糖组分总量分别为151.3 g/kg和112.9 g/kg;热风干燥处理,除以上糖组分外,还检出了棉子糖和水苏糖;两个品种甘薯可溶性糖组分总量分别为203.3 g/kg和151.8 g/kg;除蔗糖外,烟薯25号甘薯各糖组分含量及其总量均显著高于冷冻干燥处理。随贮藏时间延长,两个品种甘薯中可溶性糖组分总量均呈先增加后降低的趋势,其中,烟薯25号在贮藏45 d后达到最高,普薯32号则在贮藏15 d后达到最高;烟薯25号甘薯中葡萄糖、果糖、麦芽糖和可溶性糖组分总量在各贮藏期均显著高于普薯32号,而蔗糖则在整个贮藏期间均低于普薯32号。结论 贮藏过程可使甘薯中可溶性糖含量增加,贮藏15~45 d可溶性糖含量达到最高。冷冻干燥比热风干燥更好的保持了甘薯样品可溶性糖分组成的稳定性。     

Changes in pigment profile and surface colour of fig (Ficus carica L.) during drying

In this study, anthocyanins in three fresh fig varieties (Ficus carica L.) cultivated in Turkey were characterised and quantified by HPLC/DAD and HPLC/MS. In addition, the carotenoid composition of Sar?lop and Sar?zeybek, yellow fig varieties, was determined, and then the ripening‐ and drying‐related changes in carotenoids and surface colour of figs were monitored during conventional sun‐drying. Four different anthocyanins, cyanidin‐3‐glucoside, cyanidin‐3,5‐diglucoside, cyanidin‐3‐rutinoside (major anthocyanin) and pelargonidin‐3‐glucoside, were identified in samples. Lutein, zeaxanthin, β‐cryptoxanthin and β‐carotene were carotenoids in yellow fig varieties. Approximately 80% of carotenoid compounds in yellow fig varieties degraded at the end of drying (i.e. seventh day). L (lightness), a (redness and greenness) and b (yellowness and blueness) colour parameters were measured by Hunter Lab system. Great changes in carotenoid composition and surface colour were observed at ripening stage on tree. A significant reduction in L and b values that refers to browning in figs was made in the first 3 days of drying process.     

Changes in inulin and soluble sugar concentration in artichokes (Cynara scolymus L.) during storage

BACKGROUND: The artichoke (Cynara scolymus L.) accumulates about 50–70 g kg^?1 of its fresh weight as inulin‐type fructan. Inulin fermentation increases gas production and thereby provokes intestinal discomfort in some people. The present research focuses on the changes in carbohydrate composition occurring in artichoke heads during storage under different conditions (18 °C, 4 °C and 4 °C under polypropylene film packing). RESULTS: Carbohydrate content and composition were determined by anion‐exchange high‐performance liquid chromatography with pulsed amperometric detection. Storage time caused a decrease in inulin content and an average degree of polymerization, accompanied by an increase of free fructose and sucrose due to depolymerization of inulin. CONCLUSION: Higher‐temperature storage and storage without packing induce strong carbohydrate changes. Thereby, eating stored artichoke leads to consumption of an inulin quantity that does not provoke unwanted symptoms related to gas production but sufficient to have a prebiotic effect. Copyright © 2010 Society of Chemical Industry     

Aflatoxin contamination of pods of Indian Cassia senna L. (Caesalpinaceae) before harvest, during drying and in storage: Reasons and possible methods of reduction

The presence of aflatoxins in senna plants was studied in two different areas of India using an HPLC method. Only pods of Cassia senna angustifolia contained aflatoxins: leaves and flowers were free. Damage by insect larvae (Ephestia elutella) led to aflatoxin formation by fungi in the pods. Fruits damaged by other factors can also contain aflatoxins. The occurrence of aflatoxins in senna pods in South India proved to be unevenly distributed. Before harvest, 55% of samples contained less than 2 μg/kg, and 25% more than 10 μg/kg, with a maximum of 255 μg/kg. Controlled sun drying of pods allowed the aflatoxin content to double, while drying in the shade was followed by a four-fold increase. Only a very small fraction of dried senna pods carried the maximum load of aflatoxins. During storage of Indian senna pods, the aflatoxin content usually fell.

The smallest increase of aflatoxins, but still giving rise to unacceptably high levels, was achieved using a solar dryer. The formation of aflatoxins in Indian senna pods could also be reduced by application of NeemAzal T/S^® and even more by a fresh neem leaf water extract, but not to below the desired level of 2 μg/kg. Northern Indian harvest methods, used in South India, resulted in a reduction of aflatoxins, but again not sufficiently, and with a reduced economic output. Sudan senna (C. senna acutifolia), grown in South India, showed resistance to fungal infections and the aflatoxin content was lower than in Indian senna (C. senna angustifolia), in the field and in the laboratory, but growing Sudan senna elsewhere in India was not economical. The consequences of the findings are discussed.     

Water sorption and cooking time of red kidney beans (Phaseolus vulgaris L.): part I – Effect of freezing and drying conditions on water sorption and cooking time

Water sorption and cooking time of kidney beans were determined. The beans were manually harvested at 19.2 ± 0.1% moisture content and stored at ?20 and ?10 °C for about half a year. The beans were further dried at 30, 40 and 50 °C inside a thin‐layer drier for 7.5 h or under room conditions for 4 week. The freezing storage temperature before the beans were dried did not influence their cooking time and water sorption. The saturated kernel volumes decreased approximately 7% after drying. The beans decreased their sphericity during water sorption and had a larger swelling ratio in the thickness direction than in other directions. Lower initial moisture content, especially with a higher drying temperature, decreased water sorptivity and resulted in higher percentage of uncooked kernels if the beans were not soaked before cooking. However, there was no relationship between initial moisture content and uncooked percentage if the beans were soaked before cooking. High drying temperature resulted in hard‐to‐cook (HTC) phenomenon.     

Drying characteristics and thermal degradation kinetics of hardness,anthocyanin content and colour in purple‐ and red‐fleshed potato (Solanum tuberosum L.) during hot air drying

Purple‐fleshed potatoes (PFP) and red‐fleshed potatoes (RFP) were dried using hot air. The hardness, anthocyanin content and colour in PFP and RFP during drying were evaluated at 60, 70 and 80 °C. The hardness was characterised by a softening stage in the early drying period, followed by a hardening stage. The times to reach at the transition were 420, 300 and 240 min at 60, 70 and 80 °C, respectively, for PFP, and 480, 360 and 240 min for RFP. However, the moisture content of both PFP and RFP at the transition time was identical at 0.3 (d.b.). The two stages of hardness changes were well described by combining two modified first‐order kinetics models. The activation energy (E_a) for the degradation of anthocyanin in PFP and RFP was 25.12 and 28.43 kJ mol^?1, respectively. The E_a values demonstrated that the thermal sensitivity of PFP was higher than that of RFP.     

Implications of spatial and temporal changes in concentration of pyruvate and glucose in onion (Allium cepa L.) bulbs during controlled atmosphere storage

BACKGROUND: Pungency and perceived sweetness are important quality assurance parameters for onion producers; however, there is still a paucity of information describing the spatial changes within the bulb of some taste‐related compounds during storage. Accordingly, onion bulbs of cultivars (cvs.), SS1 (low pungency, low dry matter) and Renate (pungent, high dry matter) bulbs, were divided into 12 sections and both spatial and temporal variations of pyruvate and glucose were recorded during standard controlled atmosphere storage. RESULTS: Pyruvate within cv. SS1 bulbs reached 8.3 µmol g^?1 fresh weight (FW) from pre‐storage levels of less than 3.4 µmol g^?1 FW, whilst pyruvate changes in cv. Renate remained in the ‘pungent’ category, between 12 µmol g^?1 FW and 15 µmol g^?1 FW; thus having fewer implications for marketing and quality assurance. Glucose concentrations were significantly higher for both cvs. in the neck region as compared to basal tissue. Higher glucose levels were recorded in the core of the bulb than in outer scales of cv. Renate. The opposite was found for cv. SS1. There was an inverse correlation of ? 0.69 and ? 0.87 between glucose and pyruvate for cvs. SS1 and Renate, respectively. CONCLUSION: In order to measure overall bulb flavour, it is recommended that sampling procedures, particularly for routine pungency determination, be carried out on bulb quarters or wedges rather than equatorial sections. Copyright © 2009 Society of Chemical Industry     

Survival of enterohaemorrhagic Escherichia coli O157:H7 strain in Turkish soudjouck during fermentation, drying and storage periods

Soudjouck (a kind of Turkish sausage) batter was inoculated with Escherichia coli O157:H7 at a level of 10⁵ colony-forming unit (CFUg) and kept overnight at 4°C. After stuffing the soudjouck batter into natural casing, fermentation was carried out at 24±2°C and 90–95% relative humidity (RH) for 3 days with subsequent drying at 22±2°C and 80–85% RH for 5 days. Then, half of soudjouck samples were vacuum-packed in polyethylene bags and the rest were kept open. All samples were stored at 4°C (55% RH) for 3 months. E. coli O157:H7 and lactic acid bacteria counts, moisture contents and pH values of the samples were determined during fermentation, drying and storage periods. Results showed that count of E. coli O157:H7 decreased by 3 log unit during fermentation and drying periods. It was observed that this pathogen survived longer in vacuum-packaged samples (more than 2 months) than non-vacuum samples (more than 1 month).     

Changes in the radical-scavenging activity of bitter gourd (Momordica charantia L.) during freezing and frozen storage with or without blanching

The effects of blanching, freezing, and frozen storage on the retention of radical-scavenging activity (RSA), total phenolics, and ascorbic acid in bitter gourd were investigated. Blanching of sliced bitter gourd resulted in considerable losses of RSA and total phenolics, and most extensively, of ascorbic acid. In the subsequent frozen storage at -18 degrees C, RSA and total phenolic content of unblanched and blanched bitter gourd underwent little change for 90 d then gradually declined, but at -40 degrees C, they practically remained unchanged throughout the entire storage period. On the contrary, ascorbic acid content of both unblanched and blanched bitter gourd decreased abruptly at the early stage in frozen storage. The results show that blanching of bitter gourd improves the retention of RSA and total phenolics during subsequent frozen storage but markedly aggravated loss of ascorbic acid. Finally, it is to be noted that RSA, total phenolics, and ascorbic acid originally contained in the raw bitter gourd were overall best retained by quick freezing followed by frozen storage at -40 degrees C without preceding blanching.     

Quercetin content in stored onions (Allium cepa L.): effects of storage conditions,cultivar, lifting time and nitrogen fertiliser level

Storage experiments with commercial cultivars of onion (Allium cepa L.) were performed at low constant temperature (1°C) and at higher variable temperature (～8°C). Cultivar differences in quercetin glucoside content were significant, but neither nitrogen fertiliser level nor lifting time had more than minor effects at start of storage or after 3 or 5 months of storage. The role of onion size for quercetin glucoside content and composition was inconsistent but seemed to be of minor importance. Irrespective of storage conditions, the content of quercetin glucosides only showed minor reduction and the composition was unchanged. After 5 months of storage, onion sprouting was recorded during a shelf‐life period of 9 weeks at room temperature. Early lifting resulted in onions with low sprouting and good storage abilities without negative effects on quercetin glucoside content. The results suggest that it may be possible to minimise nitrogen fertiliser levels without negative effects on onion yield, quercetin glucoside content or storage capacity. Copyright © 2007 Society of Chemical Industry