Abstract

Maximum permitted levels for aflatoxins in dried fruits such as almonds and apricot kernels are higherin kernels intended for further processing as compared to ready-to-eat derived products. The effect ofelectronic sorting, peeling and manual colour sorting on apricot kernels was tested to check levels anddistribution of aflatoxins. The fate of aflatoxins during transformation processes of almonds into nougat,pastries and almond syrup (blanching, roasting, water infusion and cooking) was also evaluated. Themass balance approach was used to determine levels and distribution of aflatoxins in each fractioncollected during processing steps. Experiments were conducted on naturally contaminated apricotkernels and almonds inoculated with a toxigenic strain of Aspergillus flavus. An improved HPLC-FLDmethod was used for aflatoxin determination in all the matrices considered in this study. Highly variableresults were obtained with electronic sorting experiments because rejected fractions contained 13-59%of total aflatoxins. The manual colour sorting of peeled apricot kernels gave excellent results because theremoval of discoloured kernels removed 97.3-99.5% of total aflatoxins. Blanching processes (bysteaming or boiling in water) did not reduce aflatoxin levels in blanched almonds and apricot kernelswhereas the removal of skins removed only 7-10% of total aflatoxins. Negligible amounts of aflatoxins(<1%) were found in boiling water analysed after blanching contaminated almonds or apricot kernels.Almond pastries were prepared by mixing almond paste, eggs and sugar that were cooked at 140°C for30 min, 160°C for 20 min or 180°C for 15 min. Aflatoxins were substantially stable during preparationand cooking of pastries and a slight reduction of aflatoxins (10%) was observed only at 180°C. For thepreparation of nougat the peeled almonds were roasted at 150°C for 30 min then mixed with caramel orcaramel+honey at 105°C until cooked, then shaped into small heaps. Roasting produced about 50%reduction of aflatoxins. Higher aflatoxin reduction (82%) was observed by roasting at 150°C for 120min, but almonds lost their organoleptic characteristics. The preparation and cooking of nougat produceda further consistent reduction of 54-70% of aflatoxins. Almond syrup was prepared from peeled almondpaste that was infused in water for 5 hours. After infusion the exhausted almonds were discarded and theinfuse was sugared and boiled until reaching the consistency of syrup. The whole process of almondsyrup preparation produced a marked increase of total aflatoxins probably due to the involvement ofenzymes during the infusion step that released free aflatoxins from masked aflatoxins. About 15-22% oftotal aflatoxins passed in the final syrup during the whole process of almond syrup preparation. Thesenew information could be useful for food producers to keep aflatoxin contamination under control andimprove the safety of almond

Autore Pugliese

• Epifani Filomena , Perrone Giancarlo , Solfrizzo Michele

Tutti gli autori

• Solfrizzo M.; Zivoli R.; Perrone G.; Epifani F.; Visconti A.

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Anno di pubblicazione

2013

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Settori ERC

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