Gamma irradiation of clove: level of trapped radicals and effects on bioactive composition.

BACKGROUND: Food irradiation is a widely used technique for improving the safety and shelf life of foods, including most spices. However, growing concerns by consumers about this technique require further investigation on the effects of radiation, both on the safety of the food and on its organoleptic properties. In this work, cloves of diverse origins were submitted to different irradiation doses in a 60 Co source. The presence of trapped radicals and their time-dependent decay after irradiation were assessed by electron spin resonance (ESR) spectroscopy. The volatile bioactive composition and the clove oil were evaluated before and after irradiation by gas chromatography time-of-flight mass spectrometry. RESULTS: Results show an increase of the amount of volatiles collected after irradiation, especially of caryophyllene oxide and acetic acid, although these are still minor constituents. No new compound was detected after irradiation. Radicals decay fast, and 60 days after irradiation they were undetectable by ESR. CONCLUSION: Gamma irradiation showed to be a clean technique for clove decontamination, since no significant change in the aroma or oil compositions was found, and low levels of trapped paramagnetic species, after the initial decay period, were detected upon irradiation. Furthermore, irradiation doses higher than those legally allowed are equally safe. © 2018 Society of Chemical Industry.

Thermoluminescence study of polyminerals extracted from clove and marjoram for detection purposes.

Food irradiation is a widely employed technology for food treatment. Since in several countries no regulations prevail, it is difficult to detect whether food has been irradiated or not. Among different analytical methods the study of the thermoluminescent (TL) emission of polymineral extracted from food is one of the most useful physical identification method. The aim of this work is to analyze the TL properties of inorganic polyminerals extracted from commercial clove (Syzygium aromaticum L.) and marjoram (Origanum majorana L.) spices exposed to (60)Co gamma radiation for detection purposes. The feasibility of using the TL method for irradiated food detection and absorbed dose determination is assessed.

Leaf gas exchange, chlorophyll fluorescence and pigment indexes of Eugenia uniflora L. in response to changes in light intensity and soil flooding.

The interactive effects of changing light intensity and soil flooding on the photosynthetic performance of Eugenia uniflora L. (Myrtaceae) seedlings in containers were examined. Two hypotheses were tested: (i) the photosynthetic apparatus of shade-adapted leaves can be rapidly acclimated to high light after transfer from shade to full sun, and (ii) photosynthetic acclimation to changing light intensity may be influenced by soil flooding. Seedlings cultivated in a shade house (40% of full sun, approximately 12 mol m(-)(2) day(-)(1)) for 6 months were transferred to full sun (20-40 mol m(-2) day(-1)) or shade (30% of full sun, approximately 8 mol m(-2) day(-1)) and subjected to soil flooding for 23 days or not flooded. Chlorophyll content index (CCI), chlorophyll fluorescence, leaf weight per area (LWA), photosynthetic light-response curves and leaf reflectance indexes were measured during soil flooding and after plants were unflooded. The CCI values increased throughout the experiment in leaves of shaded plants and decreased in leaves of plants transferred to full sun. There were no significant interactions between light intensity and flooding treatments for most of the variables analyzed, with the exception of Fv/Fm 22 days after plants were flooded and 5 days after flooded plants were unflooded. The light environment significantly affected LWA, and light environment and soil flooding significantly affected the light-saturated gross CO(2) assimilation rate expressed on area and dry weight bases (A(max-area) and A(max-wt), respectively), stomatal conductance of water vapor (g(ssat)) and intrinsic water use efficiency (A/g(s)). Five days after flooded plants were unflooded, the normalized difference vegetation index (NDVI) and the scaled photochemical reflectance index (sPRI) were significantly higher in shade than in sun leaves. Thirty days after transferring plants from the shade house to the light treatment, LWA was 30% higher in sun than in shade leaves, and A(max)(-area) and g(ssat) were 59% and 99% higher, respectively, in shade than in sun leaves. Changes in CCI, NDVI and sPRI in leaves of E. uniflora seedlings transferred from shade to full sun appear to be associated with changes in pigment composition and protective mechanisms against excess light.