Phytochemical and physical properties of blueberries, tart cherries, strawberries, and cranberries as affected by different drying methods.
The effects of hot-air drying (AD), freeze drying (FD) and Refractance Window drying (RWD) on the retention of anthocyanins, phenolics, flavonoids, vitamin C and B, and antioxidant capacity (ORAC) in blueberries, tart cherries, strawberries, and cranberries, as well as organic acids and proanthocyanins in cranberries and chlorogenic acid and catchins in blueberries were evaluated. Changes in color, glass transition, specific heat, and surface morphology of the dried fruits were also evaluated. The quality retention in the dried fruits was found to be product and drying method specific. The FD products exhibited a better retention of vitamin C, ORAC, anthocyanins, and phenolics than the AD and RWD fruits. The RWD produced samples with a less effective ORAC, anthocyanins, and phenolics retention, but a higher total vitamin B retention compared to the FD products. The AD-dried fruits displayed significantly lesser quality retention in most of the quality indexes measured in the study.
Effect of potassium sorbate (E‐202) and the antifungal PgAFP protein on Aspergillus carbonarius growth and ochratoxin A production in raisin simulating media.
BACKGROUND: Ochratoxin A (OTA) is a mycotoxin produced by several species of Aspergillus and Penicillium fungi. The presence of OTA in raisins is mainly related to the black Aspergillus spp. contamination. This toxin poses risks to human and animal health due to their high toxicity and carcinogenicity. Therefore, new strategies to avoid the risk associated to OTA are necessary. RESULTS: In the present study, a comparison between the effects of the antifungal protein PgAFP and potassium sorbate (E-202), on the growth of Aspergillus carbonarius, biosynthetic- and stress-related gene expression and its OTA production at two water activity (aw ) levels 0.95 and 0.93 aw , was carried out. The results showed that PgAFP successfully controlled OTA production, whereas E-202, although was able to decrease Aspergillus carbonarius growth, caused a significant increase in OTA production by the fungus. CONCLUSION: PgAFP protein, a biological compound with an antifungal activity, is safer to use compared to E-202 and may be proposed as a food preservative and a useful biocontrol strategy to control ochratoxigenic A. carbonarius in raisins.
Rapid, simultaneous and non-destructive assessment of the moisture, water activity, firmness and SO 2 content of the intact sulphured-dried apricots using FT-NIRS and chemometrics.
The potential of using FT-NIR spectroscopy for the rapid and non-destructive measurement of the moisture, water activity, firmness and SO2content of the intact sulphured-dried apricots (SDA) was investigated for the first time in the literature. The partial least squares regression (PLS-R) models constructed using FT-NIR spectra were very successful in predicting the moisture content (R2p = 0.986, RMSEP = 1.22%, RPD = 9.15) and water activity (R2p = 0.987, RMSEP = 0.016, RPD = 9.37) of SDAs. Satisfactory results were also obtained for the models developed for the prediction of the firmness (R2p = 0.845, RMSEP = 0.445, RPD = 2.55) and SO2 content (R2p = 0.804, RMSEP = 349 mg kg-1, RPD = 2.27). These results clearly demonstrate that the major quality parameters of SDA can be simultaneously measured in a short time by FT-NIR spectroscopy without any need for the sample preparation or skilled laboratory personnel.
Influence of Storage and Roasting on the Quality Properties of Kernel and Oils of Raw and Roasted Peanuts.
The changes in chemical properties of the peanut varieties (NC-7 and ÇOM) in the raw and roasted forms stored at 30°C for 8 months were monitored. Acidity and peroxide values of raw and roasted NC-7 and ÇOM kernel oils increased during storage. The unsaturated fatty acids such as oleic, linoleic acids of roasted peanut oils gradually decreased during storage. While the oleic acid contents of raw NC-7 oil changed 46.14% (month 0) and 43.14% (month 8), the oleic acid contents of roasted NC-7 kernel oils varied between 42.38% (month 8) and 45.61% (month 0) during storage. In addition, while the oleic acid contents of raw ÇOM kernel oil decreased from 49.87% (month 0) to 46.09% (month 7), the oleic acid contents of roasted ÇOM kernel oil decreased from 48.88% (month 0) to 45.24% (month 8) during storage. The highest linoleic acid were found in the initial periods of storage for raw and roasted NC-7 and ÇOM oils. In addition, the α-tocopherol contents of both raw and roasted peanut kernel oils changed between 20.38 mg/100 g (0.month) and 17.58 mg/100 g (month 8) to 21.45 mg/100g (month 0) and 18.64 mg/100 g (month 8) during storage, respectively. Significant variations were observed in tocopherol contents of peanut varieties due to processing.
Polyphasic approach to the identification and characterization of aflatoxigenic strains of Aspergillus section Flavi isolated from peanuts and peanut-based products marketed in Malaysia.
Peanuts are widely consumed as the main ingredient in many local dishes in Malaysia. However, the tropical climate in Malaysia (high temperature and humidity) favours the growth of fungi from Aspergillus section Flavi, especially during storage. Most of the species from this section, such as A. flavus, A. parasiticus and A. nomius, are natural producers of aflatoxins. Precise identification of local isolates and information regarding their ability to produce aflatoxins are very important to evaluate the safety of food marketed in Malaysia. Therefore, this study aimed to identify and characterize the aflatoxigenic and non-aflatoxigenic strains of Aspergillus section Flavi in peanuts and peanut-based products. A polyphasic approach, consisting of morphological and chemical characterizations was applied to 128 isolates originating from raw peanuts and peanut-based products. On the basis of morphological characters, 127 positively identified as Aspergillus flavus, and the other as A. nomius. Chemical characterization revealed six chemotype profiles which indicates diversity of toxigenic potential. About 58.6%, 68.5%, and 100% of the isolates are positive for aflatoxins, cyclopiazonic acid and aspergillic acid productions respectively. The majority of the isolates originating from raw peanut samples (64.8%) were aflatoxigenic, while those from peanut-based products were less toxigenic (39.1%). The precise identification of these species may help in developing control strategies for aflatoxigenic fungi and aflatoxin contamination in peanuts, especially during storage. These findings also highlight the possibility of the co-occurrence of other toxins, which could increase the potential toxic effects of peanuts.
Cultural and Genetic Approaches to Manage Aflatoxin Contamination: Recent Insights Provide Opportunities for Improved Control.
Aspergillus flavus is a morphologically complex species that can produce the group of polyketide derived carcinogenic and mutagenic secondary metabolites, aflatoxins, as well as other secondary metabolites such as cyclopiazonic acid and aflatrem. Aflatoxin causes aflatoxicosis when aflatoxins are ingested through contaminated food and feed. In addition, aflatoxin contamination is a major problem, from both an economic and health aspect, in developing countries, especially Asia and Africa, where cereals and peanuts are an important food crops. Early measures for control of A. flavus infection and consequent aflatoxin contamination centered on creating unfavorable environments for the pathogen and destroying contaminated products. While development of atoxigenic (non-aflatoxin producing) strains of A. flavus as viable commercial biocontrol agents has marked a unique advance for control of aflatoxin contamination, particularly in Africa, new insights into the biology and sexuality of A. flavus are now providing opportunities to design improved atoxigenic strains for sustainable biocontrol of aflatoxin. Further, progress in the use of molecular technologies such as incorporation of antifungal genes in the host and host-induced gene silencing, is providing knowledge that could be harnessed to develop germplasm that is resistant to infection by A. flavus and aflatoxin contamination. This review summarizes the substantial progress that has been made to understand the biology of A. flavus and mitigate aflatoxin contamination with emphasis on maize. Concepts developed to date can provide a basis for future research efforts on the sustainable management of aflatoxin contamination.
Effect of roasting conditions on pigment composition and some quality parameters of pistachio oil.
Pistachio roasting before oil extraction increases consumer preference but may cause changes in the oil composition. In this work, the effect of different roasting conditions on the physical parameters, oxidative stability, and pigment composition of pistachio oil extracted by pressure was studied. Density value of pistachio oil was reduced with severe roasting conditions (125 °C), while viscosity increased slightly. This adverse effect was compensated by a significant increase in both oxidative stability and, especially, in the content of chlorophyll and carotenoid pigments. Pistachio roasting temperature had a clear impact on the color of the pistachio oils, changing from yellow in oils from raw or minimally roasted pistachios (50-75 °C) to brilliant green in oils from pistachios subjected to higher temperature treatments (100-125 °C). An increase in temperature favored the pigment transfer to the oil. The green oils had a total pigment content between 2.3 and 4 times higher than the yellow oils.
Risk assessment of exposure to aflatoxin B1 and ochratoxin A through consumption of different Pistachio (Pistacia Vera L.) cultivars collected from four geographical regions of Iran.
Iran is one of the main suppliers of pistachio for the European market accounting for over 90% of its demands; hence, efficient analytical methods are required for detection of mycotoxins contamination in pistachio kernels before exporting them. In this study, aflatoxin B1 (AFB1) and ochratoxin A (OTA) levels in five pistachio cultivars collected from four sites of Iran, were measured by HPLC. Based on the results, risk assessment for AFB1 and OTA residues was done. The highest mean concentrations of AFB1 and OTA were found in Ahmad-aghaei (4.33 and 2.19 ng/g, respectively) and Akbari (4.08 and 1.943 ng/g, respectively) cultivars from Rafsanjan, Iran. Even the highest concentrations of AFB1 and OTA in analyzed samples were lower than the corresponding maximum limits set by EU authorities. The hazard index (HI) value for consumers of Iranian pistachio is below one. It could be concluded that consumption of pistachio cultivated in these regions poses no health risk of mycotoxins exposure.
Chemical Characterization and Release of Polyphenols from Pecan Nut Shell [Carya illinoinensis (Wangenh) C. Koch] in Zein Microparticles for Bioactive Applications.
The pecan nut [Carya illinoinensis (Wangenh) C. Koch] is a natural source of polyphenols with antioxidant properties. In this study, the encapsulation of aqueous and hydroalcoholic extracts of pecan nut shell were evaluated for the release of bioactive compounds and antioxidant potential in order to explore food applications using zein as encapsulating agent. The extracts showed high contents of total phenolics, condensed tannins and high antioxidant activity. Concentrations of proanthocyanidins were 9-fold higher in hydroalcoholic extracts. The LC-DAD analysis showed that catechins were the major phenolic compounds in samples, with epigallocatechin levels up to 138.62 mg mL-1. Zein microparticles loaded with aqueous extract released 2.3 times more phenolic compounds than the hydroalcoholic extracts and the DSC thermograms showed that extracts of pecan nut shell remained thermally stable up to 240 °C. The zein microcapsules obtained in this study were efficiently encapsulated and represent an interesting additive due its high antioxidant capacity, physicochemical characteristics and morphology. The use of zein microparticles combined with natural extracts constitute a step forward in the improvement of current technology for delivering phenolic compounds with applications in functional foods and nutraceuticals.
Chemical characterization of a variety of cold-pressed gourmet oils available on the Brazilian market.
Different specialty extra virgin oils, produced by cold-pressing fruits/nuts (olive, pequi, palm, avocado, coconut, macadamia and Brazil nut) and seeds (grapeseed and canola), and retailed in the Brazilian region of Minas Gerais, were chemically characterized. Specifically, for each type of oil, the fatty acid composition was elucidated by GC-FID, the contents of selected polyphenols and squalene were determined respectively by UHPLC-MS and UHPLC-PDA, whereas minerals were explored by means of ICP-MS. Olive oil was confirmed to have the highest MUFA content due to a valuable level of oleic acid, while oils from grapeseed, Brazil nut and canola were marked by nutritionally important PUFA levels. The highest SFA content found in coconut oil was mainly due to the high levels of lauric acid, known for its advantageous HDL-raising effects. As for polyphenols, gourmet oils from palm, coconut and canola showed higher levels of phenolic acids (e.g. p-hydroxybenzoic, ferulic, syringic, acids) than olive oil, which was though characterized by peculiar antioxidants, such as tyrosol and hydroxytyrosol. Also, olive oil had the highest amount of squalene, followed by the oil from Brazil nut. Finally, all the investigated oils had very low levels (order of μg/kg) of pro-oxidant elements, such as Cu, Fe and Mn. Overall, these findings may fill the gaps still present in literature on certain compositional aspects of commercially available gourmet oils.