Journal of the Science of Food and Agriculture

Ghali, Ridha; Khlifa, Karima H; Ghorbel, Hayat; Maaroufi, Khira; Hedilli, Abderrazak

doi: 10.1002/jsfa.4069pmid: 20812375

BACKGROUND: To investigate natural aflatoxin occurrence, a total of 180 samples of different foods widely consumed in Tunisia were analysed by an in‐house‐validated high‐performance liquid chromatography method including affinity column clean‐up and post‐column bromination techniques. RESULTS: The method used appeared to be rapid, selective and reproducible, and its performances were established. Detection limits were 0.05 ng g−1 for aflatoxin B1 and 0.025 ng g−1 for aflatoxins B2, G1 and G2. Aflatoxins were detected in all investigated commodities except rice, with an overall contamination frequency of 34.4% and concentrations ranging from 0.1 to 40.6 ng g−1. Aflatoxin B1 was found in all contaminated samples. Sorghum, spices and nuts were most contaminated. CONCLUSION: This study has provided an effective analytical method for the reliable determination of aflatoxins in food samples. Over one‐third of the samples investigated were contaminated with aflatoxins. Sorghum, spices and nuts were most contaminated, whereas rice showed no contamination. Copyright © 2010 Society of Chemical Industry

Havlik, Jaroslav; Plachy, Vladimir; Fernandez, Javier; Rada, Vojtech

doi: 10.1002/jsfa.4089pmid: 20661929

BACKGROUND: The meat alternatives market offers a wide range of products resembling meat in taste, flavour or texture but based on vegetable protein sources. These high protein–low purine foods may find application in a low purine or purine‐free diet, which is sometimes suggested for subjects with increased serum urate levels, i.e. hyperuricaemia. RESULTS: We determined purine content (uric acid, adenine, guanine, hypoxanthine, xanthine) in 39 commercially available meat substitutes and evaluated them in relation to their protein content. Some of the products contained a comparable sum of adenine and hypoxanthine per protein as meat. Analysis of variance showed an influence of protein source used. Mycoprotein‐based products had significantly higher contents (2264 mg kg−1) of adenine and hypoxanthine per kg of 100% protein than soybean‐based products (1648 mg kg−1) or mixtures consisting of soybean protein and wheat protein (1239 mg kg−1). CONCLUSION: Protein‐rich vegetable‐based meat substitutes might be generally accepted as meat alternatives for individuals on special diets. The type of protein used to manufacture these products determines the total content of purines, which is relatively higher in the case of mycoprotein or soybean protein, while appearing lower in wheat protein and egg white‐based products. These are therefore more suitable for dietary considerations in a low‐purine diet for hyperuricaemic subjects. Copyright © 2010 Society of Chemical Industry

Rivera‐Pastrana, Dulce M; Yahia, Elhadi M; González‐Aguilar, Gustavo A

doi: 10.1002/jsfa.4092pmid: 20632382

BACKGROUND: Tropical fruits are rich in phenolic and carotenoid compounds, and these are associated with cultivar, pre‐ and postharvest handling factors. The aim of this work was to identify major phenolics and carotenoids in ‘Maradol’ papaya fruit and to investigate their response to storage temperature. RESULTS: Ferulic acid, caffeic acid and rutin were identified in ‘Maradol’ papaya fruit exocarp as the most abundant phenolic compounds, and lycopene, β‐cryptoxanthin and β‐carotene were identified in mesocarp as the major carotenoids. Ranges of contents of ferulic acid (1.33–1.62 g kg−1 dry weight), caffeic acid (0.46–0.68 g kg−1 dw) and rutin (0.10–0.16 g kg−1 dw) were found in papaya fruit, which tend to decrease during ripening at 25 °C. Lycopene (0.0015 to 0.012 g kg−1 fresh weight) and β‐cryptoxanthin (0.0031 to 0.0080 g kg−1 fw) were found in fruits stored at 25 °C, which tend to increase during ripening. No significant differences in β‐carotene or rutin contents were observed in relation to storage temperature. CONCLUSION: Phenolics and carotenoids of ‘Maradol’ papaya were influenced by postharvest storage temperature with exception of β‐carotene and rutin. Ripe papaya stored at 25 °C had more carotenoids than those stored at 1 °C. Low (chilling) temperature (1 °C) negatively affected the content of major carotenoids, except β‐carotene, but preserved or increased ferulic and caffeic acids levels, as compared to high (safe) temperature (25 °C). Copyright © 2010 Society of Chemical Industry

Petkovsek, Maja Mikulic; Slatnar, Ana; Stampar, Franci; Veberic, Robert

doi: 10.1002/jsfa.4093pmid: 20662009

BACKGROUND: Phenolics in fruit may be influenced by the fruit type, cultivation conditions of a plant, climatic conditions, growing season, storage conditions, and industrial processing. The aim of this study was to compare single phenolic compounds, total phenolics and antioxidant capacity of four varieties of apple grown under organic and integrated conditions over a 2‐year period. RESULTS: Several different phenolic compounds belonging to the groups of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols and anthocyanins were quantified. The levels of all analysed groups of phenolics were higher (not always significantly) in the organically grown apple leaves and fruit than in the leaves or apples from integrated production. Leaves from organic trees had 10–20% higher content levels of total phenols than the leaves from trees in the integrated growing system. In both years, organic production affected the increase in the antioxidant activity of apple peel. Organic apples have higher total phenolic content than the integrated grown ones. CONCLUSION: Cultivation type had an important influence on the polyphenolic level and antioxidant capacity of the apple fruits and leaves. Apples from organic production showed a higher content of hydroxycinnamic acids, flavanols, dihydrochalcones, quercetins and total phenolics than apples from integrated cultivation. Copyright © 2010 Society of Chemical Industry

Larrigaudière, Christian; Vilaplana, Rosa; Recasens, Inmaculada; Soria, Yolanda; Dupille, Eve

doi: 10.1002/jsfa.4094pmid: 20672331

BACKGROUND: ‘Diffuse skin browning’ (DSB) is a physiological disorder that affects Golden Delicious apples treated with 1‐methylcyclopropene (1‐MCP). Although a very high incidence is found, very little is known about the etiology of this disorder. This study aims to provide an understanding of the causes of this disorder and prevent it. RESULTS: A very high incidence of DSB was found in 1‐MCP‐treated apples independent of the location of the orchard. Similar to superficial scald, harvest maturity determines the DSB incidence, with the more mature fruit being less sensitive. The 1‐MCP dose (156 nL L−1 or 625 nL L−1) and the temperature at which the 1‐MCP treatment was applied (0.5 or 20 °C) did not affect the incidence of DSB. Diphenylamine (DPA) treatment did not prevent DSB, contrary to superficial scald. Additionally, controlled atmosphere storage only partially reduced the incidence of DSB, whereas progressive cooling strategies completely inhibited DSB occurrence. A direct correlation was found between the sensitivity of the Golden Delicious clone to russeting and its sensitivity to develop DSB during storage. CONCLUSION: Our results indicated that DSB and superficial scald are two different disorders involving different oxidative processes. DSB can be prevented by progressive cooling and selection of russeting‐resistant clones. Copyright © 2010 Society of Chemical Industry

Katsube, Takuya; Yamasaki, Masayuki; Shiwaku, Kuninori; Ishijima, Tomoko; Matsumoto, Ichiro; Abe, Keiko; Yamasaki, Yukikazu

doi: 10.1002/jsfa.4096pmid: 20648552

BACKGROUND: Mulberry therapies on type 2 diabetic patients or streptozotocin‐induced diabetic rats have been reported to improve fasting blood glucose levels. We investigated the effects of dietary consumption of mulberry‐leaf powder and purified quercetin 3‐(6‐malonylglucoside), the quantitatively major flavonol glycoside in mulberry leaves, on glucose and lipid metabolism in high‐fat diet‐induced obese mice. Male C57BL/6J mice aged 8 weeks were assigned to three groups (control, mulberry leaf powder (MLP), and quercetin 3‐(6‐malonylglucoside) (Q3MG)) and treated with their respective diets for 8 weeks. RESULTS: We found that dietary supplementation of 10 g MLP kg−1 or 1 g Q3MG kg−1 in high‐fat diet effectively suppressed blood glucose levels. We also noted increased expression of glycolysis‐related genes and suppression of thiobarbituric acid reactive substances concentrations in the liver of Q3MG group compared to control mice. CONCLUSION: Dietary consumption of Q3MG, the quantitatively major flavonol glycoside in mulberry leaves, improved hyperglycemia in obese mice and reduced oxidative stress in the liver. Copyright © 2010 Society of Chemical Industry

Nieto, Leopoldo Martínez; Hodaifa, Gassan; Lozano Peña, Juan Luis

doi: 10.1002/jsfa.4097pmid: 20661897

BACKGROUND: Recently, diets rich in natural foods and food‐derived components, such as phenolic compounds, have received a great deal of attention because they are perceived as ‘safe’ and ‘non‐medicinal’. In fact, some are known to function as chemopreventive agents against oxidative damage, cerebrovascular disease, and aging. RESULTS: Phenolic compounds, natural antioxidants present in virgin olive oil, play an important role in oil quality by contributing significantly to protecting oil stability against oxidation. In addition, polyphenols are the main contributors to olive oil bitterness, astringency and pungency. The data were fit by linear regression, giving Rancimat stability (h) = 0.18× Total polyphenols (mg L−1) in the virgin olive oil. CONCLUSIONS: The practice of harvesting ripe olives as soon as possible to produce oils of high phenolic contents and thus high oxidative stability implies bitter and piquant oils, this being admissible for oils of some varieties but detrimental to others appreciated in the market for being more fruity and sweeter. Copyright © 2010 Society of Chemical Industry

Lee, Hyeon‐Yong; He, Xinlong; Ahn, Juhee

doi: 10.1002/jsfa.4098pmid: 20672332

BACKGROUND: To evaluate the combined effects of high pressure extraction (HPE) and probiotic fermentation on the antimicrobial and antimutagenic activities, Berberis koreana was subjected to 500 MPa for 30 min and then fermented with Bifidobacterium longum B6 (HPE‐BLF) and Lactobacillus paracasei (HPE‐LPF) at 37 °C for 6 days. RESULTS: The phenol content was significantly increased to 228 mg GAE g−1 by the HPE compared to the conventional extraction (CE, 188 mg GAE g−1). The HPE‐BLF and HPE‐LPF showed the highest antimicrobial activity (MIC < 4 mg mL−1) against β‐lactam antibiotic sensitive and resistant Staphylococcus aureus. No significant mutagenic effect was observed for CE, HPE, HPE‐BLF, and HPE‐LPF extracts. The highest antimutagenic activities against frame‐shift mutant Salmonella typhimurium were observed at the HPE‐LPF (82%), followed by the HPE‐BLF (77%). CONCLUSION: The combined HPE and fermentation process could be used as an alternative extraction method for improving the extraction efficacy of medicinal plants. The results will provide pharmaceutically useful information and potential direction for finding new drug sources from medicinal plants. Copyright © 2010 Society of Chemical Industry

Pecetti, Luciano; Biazzi, Elisa; Tava, Aldo

doi: 10.1002/jsfa.4099pmid: 20672341

BACKGROUND: Spotted medic (Medicago arabica (L.) Huds.) is a minor forage species containing saponins which are reported to be biologically active. This study assessed the concentration and composition pattern of spotted medic saponins during the growing season and at senescence. The pattern of saponins was based on identification and quantification of their constituent sapogenins. At senescence, individual saponin concentrations of aerial and subterranean plant organs were also determined. RESULTS: Leaf total saponin content did not vary during the growing season and decreased remarkably at senescence. Seven sapogenins were identified and quantified during the season, bayogenin and hederagenin being the most abundant ones throughout. Total saponin content varied among plant organs at senescence, with the highest concentration in roots. A variable number of saponins from one (in seeds) to 19 (in leaves) were quantified. A clear relationship between leaf concentrations of sapogenins and those of their derivative saponins was revealed by correlation analysis. CONCLUSION: The species displayed a sapogenins/saponins pattern markedly different from those of other perennial or annual Medicago species. Saponins of queretaroic acid and 2β‐hydroxy queretaroic acid had no precedent in the Leguminosae. The high concentration of biologically active hederagenin suggested further assessment of possible effects on feeding animals. Copyright © 2010 Society of Chemical Industry

Larocca, Marilena; Rossano, Rocco; Riccio, Paolo

doi: 10.1002/jsfa.4100pmid: 20672335

BACKGROUND: Proteinases present in kiwi fruits are potentially allergenic enzymes belonging to the papain family of cysteine proteinases. Actinidin is a prominent kiwi enzyme. The study of kiwi proteinases is important for the follow‐up of fruit maturation, a deeper insight in the allergenic properties of individual proteins, and the application of kiwi proteinases for meat tenderisation and other industrial purposes. RESULTS: Kiwi crude extracts were analysed by two‐dimensional zymography on gelatin‐containing gels. The digestion by the reactivated proteolytic enzymes after electrophoresis resulted in insights into kiwi proteinases. A mixture of several enzyme isotypes with the same pI but different molecular mass was observed. Clear spots, corresponding to the proteolytic activities, were excised, digested with trypsin, and submitted to MALDI‐ToF mass spectrometry for protein identification. The most representative enzyme was actinidin. CONCLUSIONS: The innovative achievements of the present study are the: (1) two‐dimensional zymographic map of kiwi gelatinases without the need for extensive purification; and (2) direct identification of proteinase isotypes by means of direct MALDI‐ToF MS analysis of the zymographic spots. Copyright © 2010 Society of Chemical Industry