Storage quality of walnut oil containing lycopene during accelerated oxidation.
The purpose of investigation was to assess the effect of lycopene on the peroxide value, acid value, fatty acids, total phenolic content and ferric-reducing antioxidant power of walnut oil. Walnut oil was extracted from Xinjiang walnut variety using cold pressing method. Our study reported that after 45 days of accelerated oxidation at 60 °C (Schaal oven test), 0.005% lycopene exhibited the greatest antioxidant effect than other addition levels of lycopene. Therefore, under ambient storage conditions, the shelf-life of walnut oil could be extended up to 16 months by 0.005% lycopene. Moreover, 0.005% lycopene added to walnut oil had a significantly higher content of saturated fatty acid, unsaturated fatty acid, total phenol, reducing ability of the polar and non-polar components than the blank sample (walnut oil without any addition of lycopene). In conclusion, lycopene improved the quality of walnut oil because of its antioxidant effect against lipid oxidation.
Changes of free-form volatile compounds in pre-treated raisins with different packaging materials during storage.
The aroma profiles of volatile compounds (VOCs) were analyzed by GC/MS in pre-treated air-dried (PAD) and sun-dried (PSD) raisins during storage. Total 98, 94 and 81 VOCs were identified in Zixiang Seedless raisins (ZSRs), Centennial Seedless raisins (CSRs) and Thompson Seedless raisins (TSRs), respectively. During storage, the overall concentrations of VOCs of PSD raisins were higher in plastic bag (PB) compared to those in woven bag (WB). Regarding fruity and floral aromas, the effect of PAD and PB was significant throughout the storage periods (3, 6 and 9 months), however, fatty aroma was higher in PSD raisins due to the major contribution of 2,3-butanedione. The main fruity and floral aroma contributors were β-damascenone, limonene, rose oxide, geraniol and ethyl hexanoate. This study showed that compounds came from unsaturated fatty acid oxidation, glycosidically-derived and grape-derived source were contributed to fruity, floral or herbaceous aromas, but Maillard reaction-derived VOCs imparted fatty and roasted aromas.
Effects of packaging materials on storage quality of peanut kernels.
In order to obtain optimum packaging materials for peanut kernels, the effects of four types of packaging materials on peanut storage quality (coat color, acid value, germination rate, relative damage, and prevention of aflatoxin contamination) were examined. The results showed that packaging materials had a major influence on peanut storage quality indexes. The color of the peanut seed coat packaged in the polyester/aluminum/polyamide/polyethylene (PET/AL/PA/PE) composite film bag did not change significantly during the storage period. Color deterioration was slower with polyamide/polyethylene (PA/PE) packaging materials than with polyethylene (PE) film bags and was slower in PE bags than in the woven bags. The use of PET/AL/PA/PE and PA/PE bags maintained peanut quality and freshness for more than one year and both package types resulted in better germination rates. There were significant differences between the four types of packaging materials in terms of controlling insect pests. The peanuts packaged in the highly permeable woven bags suffered serious invasion from insect pests, while both PET/AL/PA/PE and PA/PE bags effectively prevented insect infection. Peanuts stored in PET/AL/PA/PE and PA/PE bags were also better at preventing and controlling aflatoxin contamination.
Insight into Genes Regulating Post-harvest Aflatoxin Contamination of Tetraploid Peanut from Transcriptional Profiling.
Post-harvest aflatoxin contamination is a challenging issue that affects peanut quality. Aflatoxin is produced by fungi belonging to the Aspergilli group, and is known as an acutely toxic, carcinogenic and immune-suppressing class of mycotoxins. Evidence for several host genetic factors that may impact aflatoxin contamination has been reported, e.g., genes for lipoxygenase (PnLOX1 and PnLOX2/PnLOX3 that showed either positive or negative regulation with Aspergillus infection), ROS, and WRKY (highly associated with or differentially expressed upon infection of maize with A. flavusAspergillus flavus between resistant (ICG 1471) and susceptible (Florida-07) cultivated peanut genotypes. The gene expression profiling analysis was designed to reveal differentially expressed genes in response to the infection (infected vs mock-treated seeds). In addition, the differential expression of the fungal genes was profiled. The study revealed the complexity of the interaction between the fungus and peanut seeds as expression of a large number of genes was altered including some in the process of plant defense to aflatoxin accumulation. Analysis of the experimental data with 'keggseq', a novel designed tool for KEGG enrichment analysis, showed the importance of alpha-linolenic acid metabolism, protein processing in endoplasmic reticulum, spliceosome, and carbon fixation and metabolism pathways in conditioning resistance to aflatoxin accumulation. In addition, co-expression network analysis was carried out to reveal the correlation of gene expression among peanut and fungal genes. The results showed the importance of WRKY, TIR-NBS-LRR, ethylene, and heat shock proteins in the resistance mechanism.
Drivers of Preference and Perception of Freshness in Roasted Peanuts (Arachis spp.) for European Consumers.
Roasted peanuts are a popular snack in Europe, but their drivers of liking and perceived freshness have not been previously studied with European consumers. Consumer research to date has been focused on U.S. consumers, and only on specific peanut cultivars. In this study, 26 unique samples were produced from peanuts of different types, cultivars, origins, and with different process technologies (including baking, frying, and maceration). The peanut samples were subjected to sensory (expert panel, SpectrumTM ) and instrumental analysis (color, headspace volatiles, sugar profile, large deformation compression tests, and graded by size) and were hedonically rated by consumers in The Netherlands, Spain, and Turkey (n > 200 each). Preference Mapping (PREFMAP) on mean liking models revealed that the drivers of liking are similar across the three countries. Sweet taste, roasted peanut, dark roast, and sweet aromas and the color b* value were related to increased liking, and raw bean aroma and bitter taste with decreased liking. Further partial least square regression (PLSR) modeling of liking and perceived freshness against instrumental attributes showed that the color coordinates in combination with sucrose content and a select few headspace volatiles were strong predictors of both preference and perceived freshness. Finally, additional PLSR models focusing on the headspace volatiles only showed that liking and ''fresh'' attributes were correlated with the presence of several pyrroles in the volatile fraction, and inversely related to ''stale'' and to hexanal and 2-heptanone.
Ultrasonic-assisted extraction combined with sample preparation and analysis using LC-ESI-MS/MS allowed the identification of 24 new phenolic compounds in pecan nut shell [Carya illinoinensis (Wangenh) C. Koch] extracts.
Ultrasonic-assisted extraction combined with statistical tools (factorial design, response surface methodology and kinetics) were used to evaluate the effects of the experimental conditions of temperature, solid-to-solvent ratio, ethanol concentration and time for the extraction of the total phenolic content from pecan nut shells. The optimal conditions for the aqueous and hydroalcoholic extract (with 20% v/v of ethanol) were 60 and 80 °C; solid to solvent ratio of 30 mL·g-1 (for both) and extraction time of 35 and 25 min, respectively. Using these optimize extraction conditions, 426 and 582 mg GAE·g-1 of phenolic compounds, from the aqueous and hydroalcoholic phases respectively, were obtained. In addition, the analysis of the phenolic compounds using the LC-ESI-MS/MS system allowed the identification of 29 phenolic compounds, 24 of which had not been reported in literature for this raw material yet.
Chemical modifications of Tonda Gentile Trilobata hazelnut and derived processing products under different IR and hot‐air roasting conditions–a combined analytical study.
BACKGROUD: For the processing industry, it is crucial to know what effect the roasting process and conditions have on hazelnut quality. The present study investigates, for the first time, on the effects of hot-air and infrared (IR) roasting at different time-temperature combinations on Tonda Gentile Trilobata hazelnut: whole kernels and derived processing products (paste and oil). RESULTS: Nutritional and physical characteristics of hazelnuts and processing products were determined to study the influence of the different roasting conditions as a function of the intended use. The antioxidant profile (DPPH, ORAC and total phenolic content) were analyzed on roasted hazelnut and paste extracts. For a comprehensive understanding of the complex bio-chemical phenomena occurring during roasting, E-nose and near-infrared spectroscopy were also applied. All analytical data were processed using univariate (ANOVA) and multivariate data analyses (PCA) . Hazelnuts derived from IR roasting at higher temperatures (195°C) showed a richer antioxidant profile and a more intense flavour. On the other hand, the yield associated to the oil extraction under the same conditions was unsatisfactory making this process completely inadequate for oil production. Oil obtained by hot-air roasting and IR roasting at lower temperature (135°C) resulted to be of good quality, showing rather similar acidity grade, peroxide number and acidic composition. In particular, a slightly but significantly lower acidity was related to lower roasting temperatures (0.21-0.22% vs 0.27 % for higher temperatures). All roasting conditions tested, allow to quantitatively obtain homogeneous hazelnut paste and from a rheological point of view, higher roasting temperatures gave pastes characterised by higher density and viscosity values. CONCLUSION: IR proved to be a promising alternative method for hazelnut roasting, thanks to its capability in preserving nutritional values and enhancing organoleptic quality.
Authentication of an Italian PDO hazelnut (“Nocciola Romana”) by NIR spectroscopy.
Common hazelnuts are widely present in human diet all over the world, and their beneficial effects on the health have been extensively investigated and demonstrated. Different in-depth researches have highlighted that the harvesting area can define small variations in the chemical composition of the fruits, affecting their quality. As a consequence, it has become relevant to develop methodologies which would allow authenticating and tracing hazelnuts. In the light of this, the present work aims to develop a non-destructive method for the authentication of a specific high-quality Italian hazelnut, "Nocciola Romana," registered with a protected designation of origin (PDO). Thus, different samples of this fruit have been analyzed by near-infrared (NIR) spectroscopy and then classification models have been built, in order to distinguish between the PDO fruits and the hazelnuts not coming from the designated region. In particular, two different classification approaches have been tested, a discriminant one, partial least squares-discriminant analysis, and a class-modeling one, soft independent modeling of class analogies. Both methods led to very high prediction capability in external validation on a test set (classification accuracy in one case, and sensitivity and specificity in the other, all higher than 92%), suggesting that the proposed methodologies are suitable for a rapid and non-destructive authentication of the product.
Effect of solvent on the extraction of phenolic compounds and antioxidant capacity of hazelnut kernel.
Hazelnut kernel phenolic compounds were recovered applying two different extraction approaches, namely ultrasound-assisted solid/liquid extraction (UA-SLE) and solid-phase extraction (SPE). Different solvents were tested evaluating total phenolic compounds and total flavonoids contents together to antioxidant activity. The optimum extraction conditions, in terms of the highest value of total phenolic compounds extracted together to other parameters like simplicity and cost were selected for method validation and individual phenolic compounds analysis. The UA-SLE protocol performed using 0.1 g of defatted sample and 15 mL of extraction solvent (1 mL methanol/1 mL water/8 mL methanol 0.1 % formic acid/5 mL acetonitrile was selected. The analysis of hazelnut kernel individual phenolic compounds was obtained by HPLC coupled with DAD and MS detections. Quantitative analysis was performed using a mixture of six phenolic compounds belonging to phenolic classes' representative of hazelnut. Then, the method was fully validated and the resulting RSD% values for retention time repeatability were below 1%. A good linearity was obtained giving R2 no lower than 0.997.The accuracy of the extraction method was also assessed. Finally, the method was applied to the analysis of phenolic compounds in three different hazelnut kernel varieties observing a similar qualitative profile with differences in the quantity of detected compounds.
Polyphenol bioavailability in nuts and seeds by an in vitro dialyzability approach.
An in vitro dialyzability approach has been undertaken to elucidate the bioavailable fraction of the total polyphenols (TPs) of edible nuts and seeds. The TP contents in samples and in dialyzates were assessed by the Folin-Ciocalteu spectrophotometric method. Antioxidant activity was determined in selected samples, using a modified method against Trolox®. TPs and antioxidant activity in nuts/seeds were determined after applying a pressurized liquid extraction sample pre-treatment. High dialyzability ratios were assessed in most nuts/seeds (TP dialyzability percentages within the 25-91% range). The highest TP dialyzability ratios were found in raw Brazil nuts (81 ± 5%), toasted pistachios (88 ± 9%), and fried cashews (89 ± 9%), whereas TPs in pumpkin seeds were found to be very low (TPs were not detected in the dialyzable fraction). TP dialyzability was correlated with the copper content in nuts and seeds.