Analysis of flavour compounds and prediction of sensory properties in sea buckthorn (Hippophaë rhamnoides L.) berries

The aim of this study was to investigate sugars, organic acids, flavonol glycosides (FGs), proanthocyanidins and volatiles as flavour compounds in sea buckthorn (SB) berries of five cultivars and to predict the sensory properties of berries. The profiles of flavour compounds in SB berries varied significantly among the cultivars. Total proanthocyanidins and FGs were highest in ‘Pertsik’ and ‘Raisa’, respectively. Total volatiles were highest in ‘Vorobyevskaya’ and lowest in ‘Raisa’. A previously established PLS model was used to predict the sensory properties of SB berries based on the non-volatile flavour compounds. The mouth-drying astringency can be predicted the most reliably, which has the highest regression coefficients with quinic acid, isorhamnetin-3-O-sophoroside-7-O-rhamnoside and total proanthocyanidins. Bitterness cannot be predicted using the model. ‘Pertsik’ berries were predicted to be more mouth-drying astringency and sour than those of ‘Raisa’. The research supports the cultivar selection in cultivation and industry of SB berries.     

Astringency sub-qualities of red wines and the influence of wine–saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication.     

Beyond information seeking: Consumers’ online deliberation about the risks and benefits of red meat

Successfully engaging consumers in a dialogue may provide opportunities for better tailored and more effective communication about food-related risks and benefits. Using an online deliberation concept and software, VIZZATA™, we explored the validity of a behavioral measure of deliberation in an online environment in the context of consumers’ perceptions and information seeking about the risks and benefits of red meat. Participants from Belgium, Portugal and the United Kingdom (n = 150) were given the opportunity to engage in an asynchronous interaction with the research team about the information provided. Online deliberation was operationalized as an individual metric based on the number of questions asked in relation to the information, the number of comments left, the number of glossary terms accessed, and the time spent on deliberative activity. This operationalization provided a coherent measure of deliberation which was positively correlated with information recall about the risks and benefits of red meat. Participants who perceived the information about red meat risks and benefits as too complex engaged less with the information. The study herewith presents a novel method of investigating consumers’ deliberation about food issues that conceptualizes consumer engagement as more than just information seeking.     

Effect of Convective and Vacuum–Microwave Drying on the Bioactive Compounds,Color, and Antioxidant Capacity of Sour Cherries

The aim of this study was to determine the effect of microwave power during the vacuum–microwave drying (VMD) on sour cherries in terms of drying kinetics, including the temperature profile of dried material, as well as on some quality factors of the finished product including phenolic compounds, antioxidant capacity, and color. The content of phenolic compounds, antioxidant activity, and color change were used as quality indicators of dried sour cherries. Sour cherries were dehydrated by convective drying (CD) at temperatures of 50 °C, 60 °C, and 70 °C and by VMD at the initial microwave power of 240 W, 360 W, and 480 W reduced to 240 W and 120 W in order to avoid a rapid increase in temperature at the critical moisture content of ca. 1 kg/kg dry mass. Control samples were prepared by freeze drying (FD). The increase in air temperature during CD as well as the increase in material temperature during VMD deteriorated dried product quality in terms of the content of phenolic compounds, antioxidant activity, and color, which was consistent with anthocyanins content. However, VMD turned out to be much better than CD and competitive to FD. The best quality of the dried product and its more attractive color were achieved at VMD at 480 W followed by drying at microwave power reduced to 120 W, which corresponds to anthocyanins content. In addition, the drying process had a positive impact on contents of quercetin and keampferol derivatives. Dried sour cherries have a long shelf life and therefore may be a fine alternative to fresh fruit all year round.     

Phytochemical profile of a Japanese black–purple rice

Black–purple rice is becoming popular with health conscious food consumers. In the present study, the secondary metabolites in dehulled black–purple rice cv. Asamurasaki were analysed using HPLC–PDA–MS². The seeds contained a high concentration of seven anthocyanins (1400 μg/g fresh weight) with cyanidin-3-O-glucoside and peonidin-3-O-glucoside predominating. Five flavonol glycosides, principally quercetin-3-O-glucoside and quercetin-3-O-rutinoside, and flavones were detected at a total concentration of 189 μg/g. The seeds also contained 3.9 μg/g of carotenoids consisting of lutein, zeaxanthin, lycopene and β-carotene. γ-Oryzanol (279 μg/g) was also present as a mixture of 24-methylenecycloartenol ferulate, campesterol ferulate, cycloartenol ferulate and β-sitosterol ferulate. No procyanidins were detected in this variety of black–purple rice. The results demonstrate that the black–purple rice in the dehulled form in which it is consumed by humans contains a rich heterogeneous mixture of phytochemicals which may provide a basis for the potential health benefits, and highlights the possible use of the rice as functional food.     

Functional implications of bound phenolic compounds and phenolics–food interaction: A review

Sizeable scientific evidence indicates the health benefits related to phenolic compounds and dietary fiber. Various phenolic compounds-rich foods or ingredients are also rich in dietary fiber, and these two health components may interrelate via noncovalent (reversible) and covalent (mostly irreversible) interactions. Notwithstanding, these interactions are responsible for the carrier effect ascribed to fiber toward the digestive system and can modulate the bioaccessibility of phenolics, thus shaping health-promoting effects in vivo. On this basis, the present review focuses on the nature, occurrence, and implications of the interactions between phenolics and food components. Covalent and noncovalent interactions are presented, their occurrence discussed, and the effect of food processing introduced. Once reaching the large intestine, fiber-bound phenolics undergo an intense transformation by the microbial community therein, encompassing reactions such as deglycosylation, dehydroxylation, α- and β-oxidation, dehydrogenation, demethylation, decarboxylation, C-ring fission, and cleavage to lower molecular weight phenolics. Comparatively less information is still available on the consequences on gut microbiota. So far, the very most of the information on the ability of bound phenolics to modulate gut microbiota relates to in vitro models and single strains in culture medium. Despite offering promising information, such models provide limited information about the effect on gut microbes, and future research is deemed in this field.     

Characterisation and identification of key cardboard-like off-odour compounds and possible origins in yoghurt using HS-SPME-GC–MS

Cardboard-like off-odour in yoghurt can negatively impact consumer acceptability. Herein, a method has been developed to analyse off-odorants in yoghurt using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. Of 56 volatile organic compounds identified, 8 were active compounds responsible for cardboard-like off-odour, including 2, 2-dimethyl-propanoic acid and 3-methyl-2-pentanone, which were newly identified in yoghurt. Hexanol and hexanal were found to be indicators of quality deterioration. The off-odour may be caused by packaging materials and temperature changes during logistic activities. Overall, identifying off-odorants can help producers to determine which part of the yoghurt-producing process can be changed to avoid contamination.     

Towards improving the nutrition and health of the aged: the role of sprouted grains and encapsulation of bioactive compounds in functional bread – a review

Aging reduces the absorption of nutrients. Literature related to functional bread processing techniques including sprouting of grains and the application of encapsulation technology and the bioavailability of bioactives was reviewed. Functional ingredients including sprouted/germinated grain particularly brown rice and wheat flours enhance the bioactive properties of functional bread. Ingredients with high polyphenol content such as lavender and melissa by-products, tea-extracts and aronia powder enhance the bioactive content and appear to have a favourable effect on the shelf-life of bread and antioxidant status of consumers. Incorporation of encapsulated bioactive compounds into bread have a huge potential to improve the bread quality and increase the bioavailability and bioaccessibility of bioactive compounds including polyphenols. More investigations and new areas of research should focus on sprouted grain flours and the application of encapsulation technologies especially nanoencapsulation to optimize the bioactivity, storage, bioavailability and nutritional profile of bread to improve nutrition and health with aging.     

Analysis of volatile compounds in New Zealand unifloral honeys by SPME–GC–MS and chemometric-based classification of floral source

New Zealand unifloral honeys have a higher commercial value than polyfloral honeys; however identification of floral source can be difficult and time-consuming. In this study, we aimed to establish a rapid and semi-automated method for identifying the floral source of New Zealand honeys. Volatile compounds from ten types of New Zealand unifloral honeys (a total of 234 samples) were analyzed by solid-phase microextraction (SPME) and gas chromatography coupled to mass spectrometry (GC–MS). For 37 compounds, probability plots of log₁₀[GC–MS peak area] versus cumulative probability enabled visual identification of those that could be possible markers used to discriminate floral source. GC–MS peak areas were also analyzed by hierarchical cluster analysis and principal component analysis. Results showed data falling into groups based on floral source, indicating that supervised pattern recognition could be used to build a model with which to classify honeys based on floral source. A model was built using WEKA (Waikato Environment for Knowledge Analysis) machine-learning software. The logistic model tree algorithm in WEKA produced a model that classified 89.8 % of samples correctly. Overall, results show that the methods employed here have the potential to be used as a basis for routine testing and classification of New Zealand unifloral honeys.     

Ultrasound-assisted hydrolysis and gas chromatography–mass spectrometric determination of phenolic compounds in cranberry products

An ultrasound-assisted hydrolysis and gas chromatography–mass spectrometric (GC–MS) method has been developed for determination of phenolics in cranberry products. Prior to GC–MS separation and characterisation, the phenolics in samples were hydrolysed by hydrochloric acid with ultrasound-assistance, extracted with ethyl acetate, and derivatised with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TMCS) reagents. The application of ultrasonication significantly accelerated the acidic hydrolysation of the conjugated phenolics. A baseline separation of the 20 phenolics and internal standard was achieved in 25 min. Standard calibration curves were linear over the concentration range of 0.0–50 μg/mL and detection limits were 0.06–0.70 μg/mL. Twenty phenolics were identified in cranberry samples and all of them occurred mainly in conjugated forms. Of those, the benzoic acid, quercetin, and myricetin were most abundant phenolics. The total phenolics were 12.4 mg/g in cranberry fruits, 9.1 mg/mL in 100% cranberry juice, and 11.1 mg/g in cranberry sauces, respectively.     

Rapeseed and its Products—Sources of Bioactive Compounds: A Review of their Characteristics and Analysis

Extensive studies of rapeseed varieties, meals and rapeseed oils revealed that they are rich sources of natural components having antioxidant properties. In this review the characteristic of bioactive compounds in rapeseed cultivars, meals and oils will be presented. The analytical methods of antioxidants identification and determination are described. The effects of innovations in rapeseed modification and technology improvements on antioxidant capacity of rapeseed oil and products will be discussed.     

Release of active compounds from agar and agar–gelatin films with green tea extract

Active biodegradable films based on agar and agar–fish gelatin were developed by the incorporation of green tea aqueous extract to the film forming solution. The effect of the partial replacement of agar by fish skin gelatin as well as the addition of the green tea extract on the physical properties of the resultant films was evaluated. Special attention was given to the release of antioxidant and antimicrobial compounds from the agar film matrices with and without gelatin. Agar–gelatin films were less resistant and more deformable than agar films. The inclusion of green tea extract decreased tensile strength and elongation at break in both agar and agar–gelatin films. Water vapour permeability and water resistance was not affected either by the replacement of agar by gelatin or the addition of green tea extract, but the water solubility noticeably increased in the films containing green tea extract. The presence of gelatin in the agar–green tea matrix film hindered the release of total phenolic compounds, catechins and flavonols in water. As a consequence, the antioxidant power released by the films was lower in the case of films containing gelatin. However, the antimicrobial activity of the films was not affected by the presence of gelatin.     

Understanding the crispy–crunchy texture of raw red pepper and its change with storage time

Red sweet peppers held in cold storage were periodically sampled at 1-week intervals over a 3-weeks period using three-point bending, puncture, cutting, and Volodkevich (coupled with acoustic emission) tests, confocal laser scanning microscopy (CLSM) and other physicochemical measurements. At each sampling, tissue specimens were soaked in mannitol solutions (0.0–0.9M) and puncture test, dimension changes and CLSM were used to identify degrees of turgidity present in osmotically manipulated pepper tissue. Pepper texture became crumbly with increased storage time due to softening and wilting processes. The Young's modulus, derived from the bending test using the single-edge notched bend geometry without notches decreased progressively during cold storage and resulted as the best mechanical parameter for measuring the loss of whole-tissue stiffness by both decreased cell wall stiffness and turgor pressure. Osmotic adjustment indicated that the pepper structure is extremely anisotropic, with the specimen's “average” relative thickness (RT) being the dimension change more affected. Incipient plasmolysis was evident in the highest mannitol concentration (0.9M), therefore, the turgor pressure of nonsoaked tissue could not be inferred. However, significant correlations were found between RT and puncture parameters such as initial slope, initial and final distances, and the number of flesh and skin force peaks, which depended on the dilation or shrinkage caused by the osmotic adjustment. During storage, soaked tissues had lower crunchy texture than nonsoaked, reflecting that cell wall stiffness plays a more significant role in determining pepper crunchiness than cell turgor pressure.     

Changes after high-pressure processing on physicochemical parameters,bioactive compounds,and polyphenol oxidase activity of red flesh and peel plum purée

Physicochemical parameters (instrumental color, soluble solid content, titratable acidity, and pH), bioactive compounds (total phenols and anthocyanins), total antioxidant activity, and enzymatic activity of polyphenol oxidase (PPO) were evaluated after the application of hydrostatic high-pressure (HP) treatment on a plum purée (cv. Crimson Globe, with red flesh and peel). Different pressure levels (400, 500, and 600 MPa) were applied at different processing times (1, 150, and 300 s). HP-treated purées were compared with the untreated purée. The inactivation of indigenous microorganisms (total aerobic mesophilic and psychrotrophic counts, and molds and yeasts) of the plum purée after all high-pressure treatments was sufficient to reduce spoilage microorganisms present in plum purée to undetected levels in most of HP-treated purées. No significant changes were observed in pH and soluble solid content after processing. The combined treatments (pressure level and processing time) did not reach a sufficient inhibition of PPO enzyme. Processing induced a significant increase in L*, a*, hue, and chroma, which could enhance the redness perception of treated purées. All HP-treated purées showed a slight reduction in anthocyanins and antioxidant activity after processing. Nevertheless, total phenols were not significantly affected by HP-treatments. In conclusion, high-pressure processing keep most quality parameters and nutritional compounds levels, although, it did not achieve the inhibition of browning related enzymes, which could reduce the shelf-life of plum products during storage.Industrial relevanceHigh-pressure processing is one of the most successful technologies to obtain high-quality fruit purées. However, the application of this technology to certain products presents some difficulties due to high-pressure and usually does not affect the activity of browning related enzymes. The present study evaluates the effect of high-pressure treatments on the color, bioactive compounds, and polyphenol oxidase enzyme of plum purée. This is one of the first studies about the application of high pressure technology for the preservation of red flesh and peel plum. High-pressure treatments did not achieve the total inactivation of the polyphenol oxidase enzyme, however, total phenols and anthocyanins were well preserved after the treatments. Our results also show that redness and color luminosity of plum HP-treated purées were well retained. Therefore, high pressure processing offers the opportunity to processing plum purée with fresh-like properties. Nevertheless, the storage of the product could be limited due to the lack of effect of the pressure on the enzyme activity.     

Gas chromatographic–olfactometric characterisation of headspace and mouthspace key aroma compounds in fresh and frozen lamb meat

Two different techniques for obtaining extracts representing the most relevant aroma chemicals from grilled lamb have been developed and applied to the elucidation of the gas chromatographic−olfactometric (GC−O) profiles of grilled lamb from fresh or frozen samples. The first technique attempted to collect the aroma released during grilling; and the second one, the aroma released during eating. The GC–O work was complemented with a thorough isolation and identification study comprising liquid chromatography and dual gas chromatography with simultaneous MS and olfactometric detection. Eight different aroma compounds with meaty odours were detected of which (Z)-2-heptenal, 2,5-dimethylpyrazine, (Z)-2-decenal, 2-butyl-2-octenal, 2-acetyl-2-thiazoline and (E,E)-2,4-decadienal could be identified. Moreover, 2-isopropyl-3-methoxypyrazine, 2-methylbenzaldehyde and 4-hydroxy-3-methoxybenzaldehyde (vanillin) were described for the first time in lamb. Frozen samples contained higher levels of ethyl hexanoate and butanoic and 3-methylbutanoic acids, while samples obtained directly from the grill were richer in pyrazines. Furaneol was only important in samples directly collected from the mouth.     

Characterization of volatile compounds of pu-erh tea using solid-phase microextraction and simultaneous distillation–extraction coupled with gas chromatography–mass spectrometry

Two extraction methods, namely, solid-phase microextraction (SPME) and simultaneous distillation–extraction (SDE) both followed by gas chromatography–mass spectrometry were applied for the determination of a wide range of volatile compounds in pu-erh tea. The conditions of solid-phase microextraction including fiber selections and sampling condition optimization have been previously investigated. By the two methods, 79 volatile compounds belonging to different categories were identified. Among them, 61 volatile compounds were extracted by SDE and 67 by SPME. Qualitative and quantitative differences of pu-erh tea volatile profiles were observed by applying the two aforementioned extraction methods. SDE technique achieved higher percentages of high molecular weight alcohols, acids, and esters of low volatility, whereas SPME technique was found useful for analyzing low molecular weight alcohols, methoxy-phenolic compounds, aldehydes, ketones, and hydrocarbons of high volatility that were closely related to the characteristics of pu-erh tea aroma and its sensory perception. Therefore, SPME technique was a reliable extraction method for controlling pu-erh tea quality flavor.     

Characterization of aroma-impact compounds in yerba mate (Ilex paraguariensis) using GC–olfactometry and GC–MS

The volatile compounds of 18 yerba mate (YM) commercial brands from Argentina, Brazil, P.araguay and Uruguay were extracted using a Likens–Nickerson simultaneous distillation–extraction (SDE) apparatus, and analyzed by gas chromatography–mass spectrometry (GC–MS). Results showed that a total of 35 major volatile compounds were identified by GC–MS; among them, norisoprenoid compounds. A principal component analysis (PCA) was carried out in order to ascertain the degree of differentiation between samples and which compounds were involved. The results showed three main groups of YM corresponding to the places where they are commercialized. The first group (samples from Paraguay and Argentina) correlated positively with 6-methyl-5-hepten-2-one, octanal and 1-octanol. The second group (YM marketed in Uruguay but produced in Brazil) correlated positively with α- and β-ionone, linalool, nerol, α-terpineol, (Z)-linalool oxide and the aliphatic hydrocarbons undecane, dodecane and heptadecane. The third group (YM produced and marketed in Brazil) correlated positively with 2,4-heptadienal isomers, (E)-linalool oxide and β-cyclocitral. Through a preference test, one commercial brand was selected to be analyzed by gas chromatography–olfactometry (GC–O). Sixteen odor active compounds were perceived by GC–O analysis. It seems that the norisoprenoid compounds and components produced by fatty acid degradation play a vital role in the special aroma of yerba mate.