Total Amount Of Volatile Compounds Research Articles

Improving yield, functional properties, and aroma profile of rice bran protein through innovative extraction and precipitation methods

Rice bran is a milling byproduct and rice bran protein (RBP) is a promising source of plant-based protein. This study investigated the impact of alkaline and acid extractions followed by isoelectric point (IEP) and heat coagulation precipitations on the quality and functionalities of RBP. Alkaline extraction, followed by IEP and heat coagulation, showed the highest protein recovery of 48.77%, which is double that of conventional alkaline extraction and IEP. The FTIR data showed that β-sheet and α-helix content reduced; however, random coil and β-turn increased by acid and heat addition. Addition of heat coagulation to IEP after alkaline extraction increased solubility from 62.94% to 94.74%. However, the emulsification and surface hydrophobicity were decreased during heat and acid-assisted extraction. The in-vitro digestibility was the highest at 83.57% in alkaline-acid extraction, followed by heat and IEP. The aroma profile of RBP shows a complex mixture of ethanol-2-butoxy, 2-methyl-4-vinyl-phenol, 2,4—heptagonal, (E,E)-, Undecane, and 5-methyl to form a typical flavor with waxy and rancid undernotes. The total amount of volatile compounds in conventional extraction was 1.97 μg/g, while alkaline-acid extraction with IEP had only 0.87 μg/g. The RBP from alkaline-acid extraction with IEP showed the least volatile compounds and most neutral proteins.

Identification and selection of volatile compounds derived from lipid oxidation as indicators for quality deterioration of frozen white meat and red meat using HS-SPME-GC–MS combined with OPLS-DA

This work aimed to investigate the effects of frozen storage on volatile compounds of white meats (chicken and duck) and red meats (pork, beef, and mutton). The samples were stored at −18 °C for 0, 2, 4, 10, 18 weeks, and volatile compounds were analyzed by headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. Results indicated that the total amounts of volatile compounds increased with frozen storage duration of meats. The correlations were observed between frozen storage duration and levels of 2-ethyl-1-hexanol, tetradecane, nonanal, decanal, octanal, tridecanal, benzaldehyde, pentadecane, propanoic acid,2-methyl-,3-hydroxy-2,2,4-trimethylpentyl ester, heptadecane, and hexanal (r = 0.7456–0.9873). Levels of octanal and propanoic acid,2-methyl-,3-hydroxy-2,2,4-trimethylpentyl ester in white meat and benzaldehyde in red meat versus frozen storage duration fitted very well with zero-order reactions. Therefore, it was concluded that changes in volatile compounds derived from lipid oxidation may be used as indicators of quality deterioration during frozen storage of meat.

Analysis of volatile compounds and 5-hydroxymethylfurfural in fried chicken breast produced by air and deep-fat frying.

Two samples, simple-battered chicken (SBC) and normal-battered chicken (NBC), with different batters were deep-fat fried at various conditions and volatile compounds and 5-hydroxymethylfurfural (5-HMF) was analysed. The moisture content of the air-fried samples was significantly higher than that of the deep-fat fried samples in the same batter samples. A total of 72 volatile compounds (8 aldehydes, 15 monoterpenes, 12 sesquiterpenes, 2 terpene alcohols, 4 benzenes, 13 pyrazines, 2 pyridines, 6 furans, 5 alcohols, 2 pyrroles, and 3 others) were detected in fried chicken breast, and air-fried SBC possessed the highest total amount of volatile compounds. Furthermore, 5-HMF was exclusively detected in NBC samples; in particular, 1.27 ± 0.06 and 0.41 ± 0.02μg/mL were detected in deep- and air-fried NBC, respectively. This study indicates the potential of air frying to reduce the formation of 5-HMF while maintaining quality characteristics, suggesting the need for further study on other hazardous compounds.

Sourdough Yeast Strains Exhibit Thermal Tolerance, High Fermentative Performance, and a Distinctive Aromatic Profile in Beer Wort.

The increasing popularity of home brewing and the fast evolution of craft beer companies have fuelled the interest in novel yeasts as the main actors diversifying the beer portfolio. Here, we have characterized the thermal tolerance and brewing-related features of two sourdough (SD) isolates of Saccharomyces cerevisiae, SDy01 and SDy02, at different temperatures, 20 and 37 °C, comparing them with commercial brew strains, AaB and kNB. The SD strains exhibited tolerance to the main brewing-related stress conditions and increased growth rates and lower lag phases than the reference beer strains at both temperatures. Consistent with this, SDy01 and SDy02 displayed higher fermentative activity in terms of sugar rate depletion and the release of metabolic by-products. Moreover, SDy01 and SDy02 brewing at 20 °C increased their total amount of volatile compounds (VOCs), in particular, their esters and carboxyl compounds, as compared to the reference AaB strain. In contrast, fermentation at 37 °C resulted in a drastic reduction in the number of VOCs in wort fermented with SD yeast, especially in its level of esters. In conclusion, our results stress the high fermentative performance of SD strains in beer wort and their ability to provide a complex and specific aromatic profile at a wide range of temperatures.

Investigation into the potential mechanism of Bacillus amyloliquefaciens in the fermentation of broad bean paste by metabolomics and transcriptomics

Pixian broad bean paste is a renowned fermented seasoning. The fermentation of broad bean is the most important process of Pixian broad bean paste. To enhance the flavor of tank-fermented broad bean paste, salt-tolerant Bacillus amyloliquefaciens strain was inoculated, resulting in an increase in total amount of volatile compounds, potentially leading to different flavor characteristics. To investigate the fermentation mechanism, monoculture simulated fermentation systems were designed. Metabolomics and transcriptomics were used to explore Bacillus amyloliquefaciens' transcriptional response to salt stress and potential aroma production mechanisms. The results highlighted different metabolite profiles under salt stress, and the crucial roles of energy metabolism, amino acid metabolism, reaction system, transportation system in Bacillus amyloliquefaciens' hypersaline stress response. This study provides a scientific basis for the industrial application of Bacillus amyloliquefaciens and new insights into addressing the challenges of poor flavor quality in tank fermentation products.

Comparing Physicochemical Properties, Fatty Acid Profiles, Amino Acid Composition, and Volatile Compounds in Dry-Cured Loin: The Impact of Different Levels of Proteolysis and Lipid Oxidation.

The aim of this study is to compare the quality characteristics of dry-cured loins with different levels of proteolysis and lipid oxidation and to investigate the relationship between these factors on quality characteristics. The dry-cured loins were divided into four groups [proteolytic index (PI) and 2-thiobarbituric acid reactive substances (TBARS) of high levels (HH), PI of high level and TBARS of low level (HL), PI of low level and TBARS of high level (LH), and PI and TBARS of low levels (LL)] based on the proteolysis index and TBARS. Moisture, protein, and fat content were all significantly influenced by proteolysis and lipid oxidation (p<0.05). The total fatty acid content in the high proteolysis groups (HH and HL) was significantly lower than that in the low proteolysis groups (LH and LL; p<0.05). For total free amino acid content, HH was the highest, and LL was the lowest (p<0.05). On the other hand, there was no significant difference between HL and LH (p>0.05). In the amount of total volatile compounds, there was no significant difference between HH and HL (p>0.05), but LH and LL significantly differed (p<0.05). In conclusion, proteolysis and lipid oxidation can influence the quality characteristics of dry-cured loin. Additionally, proteolysis might be as influential in generating volatile compounds as lipid oxidation.

Formation of fluorescent substances and correlation with process flavor changes of dehydrated Maillard reaction intermediates of peanut protein hydrolysates

Maillard reaction intermediates (MRIs) derived from peanut protein hydrolysates (PPH) and xylose (Xyl) were prepared using the water bath combined with spray drying and vacuum drying. The monitoring of free amino content, browning precursors, and taste characteristics was carried out throughout the thermal treatment at low temperature, where the Maillard reaction process was slowed down, and the formation and degradation of MRIs were dynamically balanced at low conversion rates. The reaction between amino compounds and the reducing sugars contributed to the increased taste characteristics during the early phase of Maillard reaction. Fluorescence intensity was reduced after reaching its maximum value and browning intensity was significantly increased during vacuum drying, which confirmed that the Maillard reaction entered into an advanced stage. Vacuum drying also led to a significant increase in the total amount of volatile compounds in the subsequent thermal processing reaction (from 212.93 ng/g to 564.91 ng/g), which demonstrated that the higher fluorescence intensities resulted in the more accumulation of MRIs and better capabilities of flavor formation.

Oxygen as a Possible Technological Adjuvant during the Crushing or the Malaxation Steps, or Both, for the Modulation of the Characteristics of Extra Virgin Olive Oil.

In commercial terms, Extra Virgin Olive Oil (EVOO) is considered an exceptional food with excellent sensory and nutritional quality due to its taste, odor, and bioactive compounds; as such, it is of great health interest. This quality can be affected by the oxidative degradation, both chemical and enzymatic (the activity of oxidative, endogenous enzymes from the polyphenol oxidase and peroxidase olive fruit type), of essential components during the extraction and conservation of EVOO. In the bibliography, oxygen reduction during the malaxation process and oil storage has been studied in different ways. However, research concerning oxygen reduction in the crushing of the olive fruit or the malaxation of the paste, or both, in the "real extraction condition" is scarce. Oxygen reduction has been compared to control conditions (the concentration of atmospheric oxygen (21%)). Batches of 200 kg of the olive fruit, 'Picual' cultivar, were used and the following treatments were applied: Control (21% O2 Mill-21% O2 Mixer), "IC-NM": Inerted crushing -Normal malaxation (6.25% O2 Mill-21% O2 Mixer), "NC-IM": Normal crushing-Inerted malaxation (21% O2 Mill-4.39% O2 Mixer) and "IC-IM": Inerted crushing -Inerted malaxation (5.5% O2 Mill-10.5% O2 Mixer). The parameters of commercial quality covered by regulation (free acidity, peroxide value and absorbency in ultra-violet (K232 and K270)) did not suffer any change concerning the control, and so the oils belong to the commercial category of "Extra Virgin Olive Oil". The phenolic compounds of the olives involved in the distinctive bitter and pungent taste, health properties, and oxidative stability are increased with the downsizing amounts of oxygen in the IC-NM, NC-IM, and IC-IM treatments with an average of 4, 10, and 20%, respectively. In contrast, the total amount of volatile compounds decreases by 10-20% in all oxygen reduction treatments. The volatile compounds arising from the lipoxygenase pathway, which are responsible for the green and fruity notes of EVOO, also decreased in concentration with the treatments by 15-20%. The results show how oxygen reduction in the milling and malaxation stages of olive fruit can modulate the content of phenols, volatile compounds, carotenoids, and chlorophyll pigments in the EVOO to avoid the degradation of the compound with sensorial and nutritional interest.

Effect of Fermentation Humidity on Quality of Congou Black Tea.

This study investigated the effect of different fermentation humidities (55%, 65%, 75%, 85% and 95%) on congou black tea quality and bioactivity. Fermentation humidity mainly affected the tea's appearance, aroma and taste quality. The tea fermented at low humidity (75% or below) showed a decrease in tightness, evenness and moistening degree, as well as a heavy grassy and greenish scent, plus a green, astringent and bitter taste. The tea fermented at a high humidity (85% or above) presented a sweet and pure aroma, as well as a mellow taste, plus an increase of sweetness and umami. With increasing fermentation humidity, the tea exhibited a drop in the content of flavones, tea polyphenols, catechins (EGCG, ECG) and theaflavins (TF, TF-3-G), contrasted by a rise in the content of soluble sugars, thearubigins and theabrownins, contributing to the development of a sweet and mellow taste. Additionally, the tea showed a gradual increase in the total amount of volatile compounds and in the content of alcohols, alkanes, alkenes, aldehydes, ketones and acids. Moreover, the tea fermented at a low humidity had stronger antioxidant activity against 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) and a higher inhibiting capability on the activities of α-amylase and α-glucosidase. Overall results indicated the desirable fermentation humidity of congou black tea should be 85% or above.

An Analysis of Volatile Compounds and Study of Release Regularity in the Flower of Amorphophallus titanum in Four Periods

Titan arum (Amorphophallus titanum) is a rare and endangered plant in the world. It has a huge flower and releases a repulsive odor like a corpse. On the evening of 23 July 2022 (Beijing time), a titan arum in the north garden of the China National Botanical Garden in Beijing bloomed. In order to determine the components and contents of volatile compounds released by the titan arum during its flowering, the dynamic headspace adsorption method was utilized to collect the odor of the titan arum flower on the evening of 23 July (S1), the morning of 24 July (S2), the afternoon of 24 July (S3) and the evening of 24 July (S4). The volatile compounds were analyzed by automatic thermal desorption–gas chromatography/mass spectrometry. Sixty-three volatile compounds were detected in the titan arum flower in four periods. The comparison of the total volatile compounds released in four periods was S2 &gt; S3 &gt; S1 &gt; S4. The highest content of volatile compounds in the S1 period were sulfur compounds (dimethyl disulfide and dimethyl trisulfide), and the sulfur compounds were released in large amounts only in the S1 period. Dimethyl disulfide was the volatile substance with the highest content in the S1 period (20.00%). The total volatile compounds content of titan arum flower in the S2 period was the highest among the four periods. From the S2 period, the relative content of sulfur compounds decreased significantly until the S4 period. Compared with the S1 period, 1-butanol and butyl acrylate increased significantly and 1-butanol became the highest relative component of volatile compounds in the S2 period. After the S3 period, the total amount of volatile compounds began to decline and reached the lowest level in the S4 period. It is worth noting that the contents of two terpenes, α-pinene and γ-terpinene, rose from the S1 period until their height in the S3 period. From the S4 period, the contents of most volatile compounds decreased significantly. This study revealed the varieties and contents of volatile compounds in the titan arum flower at different flowering periods. The changing trend and physiological significance of dimethyl oligosulfide from the evening of flowering (S1) to the second day (S2–S4) were emphatically discussed, and this research also provides a reference for the study of the release of volatile compounds and the molecular biology of the flower fragrance of titan arum.

Study of volatile compounds of Сalendula officinalis L. flowers by the method of gas chromatography with MAS detection

A promising direction for improving the procedure of standardization of multicomponent phytoremedies is the use of so-called marker compounds, or markers – substances whose presence is characteristic only for individual medicinal raw materials. The introduction of methods of qualitative and quantitative analysis based on the use of markers is not only of great practical importance, but also of significant scientific expediency.&#x0D; One of the most common components used to make complex herbal collections are the flowers of medicinal plants, which are successfully used in medical practice both in the form of mono preparations and in the form of components of over-the-counter medicinal product of herbal origin.&#x0D; The pharmacological activity of the flowers of marigolds is due to the presence in their composition of a complex of biologically active substances, in particular essential oils, the content of which is associated with such pharmacological properties of the plant as bactericidal, antioxidant, etc. That is why it was considered expedient to search on markers for plant standardization in mixtures among essential oil components.&#x0D; The aim of the work was to study the components of the essential oil of calendula flowers (Calendula officinalis L.) by the method of gas chromatography with mass detection&#x0D; The object of the study was marigold flowers in packs of 50 g (CJSC «Liktravy», series 80310).&#x0D; The study of volatile components was carried out using the method of gas chromatography with mass detection. Chromatographic study of the studied extracts was carried out on an Agilent 6890 gas chromatograph equipped with a mass spectrometric detector (model 5973). The identification of the studied components was carried out by mass spectra and the retention time of the components.&#x0D; As a result of the conducted research, using library spectra, 59 volatile components were identified in the extract of the flowers of Calendula officinalis L., 50 were recognized: monocyclic and bicyclic monoterpenoids, sesquiterpenoids, sesquiterpene alcohols, etc.&#x0D; The major volatile components of flowers of Calendula officinalis L. are the following substances: α-cadinol, δ-cadinene, α-muurolol and epi-α-cadinol, the content of which is equal to 417.2 mg/kg, 284.2 mg/kg, 92.4 mg/kg and 75.7 mg/kg of raw material, respectively.&#x0D; The total content of all four major volatile compounds of the flowers of Calendula officinalis L. is 44.14% of the total amount of volatile compounds found in the object of research.

Effect of Ultra-High Pressure Homogenization (UHPH) and Conventional Thermal Pasteurization on the Volatile Composition of Tiger Nut Beverage.

Tiger nut beverages are non-alcoholic products that are characterized by their pale color and soft flavor. Conventional heat treatments are widely used in the food industry, although heated products are often damaging to their overall quality. Ultra-high pressure homogenization UHPH) is an emerging technology that extends the shelf-life of foods while maintaining most of their fresh characteristics. The present work deals with the comparison of the effect of conventional thermal homogenization-pasteurization (H-P, 18 + 4 MPa at 65 °C, 80 °C for 15 s.) and UHPH (at 200 and 300 MPa, and inlet temperature of 40 °C), on the volatile composition of tiger nut beverage. Headspace-solid phase microextraction (HS-SPME) was used for detecting volatile compounds of beverages, which were then identified by gas chromatography-mass spectrometry (GC-MS). A total of 37 different volatile substances were identified in tiger nut beverages, which were primarily grouped into the aromatic hydrocarbons, alcohols, aldehydes and terpenes chemical families. Stabilizing treatments increased the total amount of volatile compounds (H-P > UHPH > R-P). H-P was the treatment that produced the most changes in the volatile composition of RP, while treatment at 200 MPa had a minor impact. At the end of their storage, these products were also characterized by the same chemical families. This study evidenced the UHPH technology as an alternative processing of tiger nut beverages production that minimally modifies their volatile composition.

GC-MS-Olfactometric Characterization of Volatile and Key Odorants in Moringa (Moringa oleifera) and Kinkeliba (Combretum micranthum G. Don) Herbal Tea Infusions Prepared from Cold and Hot Brewing

Herbal teas are a popular global drink and are widely used in many traditional medicines. Key odorants are one of the main parameters to elucidate the final herbal tea’s overall quality and consumer acceptance. In the present study, for the first time, the brewing effect on volatile, key odorants, total phenolic contents, and antioxidant potential of Moringa (Moringa oleifera) and Kinkeliba (Combretum micranthum G. Don) herbal teas was comprehensively investigated. Two different infusions were studied and labeled as 25 °C/24 h (room temperature) and 98 °C/10 min (hot temperature). A total of 45 and 44 aroma compounds were detected in Moringa cold and hot teas, respectively, whereas 39 volatiles were determined in both infusion techniques for Kinkeliba herbal teas. The total amount of volatile compounds in both cold-infused herbal teas was higher than those in the hot-infused ones. Based on GC-MS-Olfactometry results, 19 and 21 key odorants in total were found in Moringa and Kinkeliba teas, respectively. The principal key odorants in Moringa teas with the highest flavor dilution (FD) factors were (E)-2-hexen-1-ol (herbal/fresh aroma), 3-hexanol (green/grassy), 2-phenyl ethanol (floral/rose), while in Kinkeliba teas they were 2-hexanol (herbal/green) and 3-penten-2-ol (green/fresh). The total phenolic content and antioxidant potential in Moringa and Kinkeliba teas increased using hot infusion. Principal component analysis showed that each tea infusion was clearly discriminated in terms of its volatile profiles. Our findings demonstrated that the brewing procedures had a significant impact on the key odorants of Moringa and Kinkeliba infusions.

The Effect of Salvia hispanica and Nigella sativa Seed on the Volatile Profile and Sensory Parameters Related to Volatile Compounds of Dry Fermented Sausage.

The aim of the study was to evaluate the effects of Salvia hispanica and Nigella sativa seed addition on the volatile compounds and sensory characteristics (with particular emphasis on odor and flavor) of traditionally produced dry fermented sausages with reduced nitrites. Five different sausage formulations were prepared: control sample; samples with 1% and 2% addition of chia seed; samples with 1% and 2% addition of black cumin seed. The sausages were subjected to analysis including proximate chemical composition, volatile compound determination, and sensory analysis. The sausages with chia seed in the amounts of 1% and 2% as well as the sample with 1% addition of black cumin seed were characterized by positive sensory features, and their overall quality was rated above 7 c.u. on a 10-point scale, similar to the control sausage. Sausage samples with the addition of cumin seed were characterized by the highest herbal odor and flavor. The addition of Salvia hispanica and Nigella sativa seed significantly affected the amount of volatile compounds in fermented sausages. Sausages with black cumin presented the greatest amount of total volatile compounds, mainly contributed by terpenes.

Physicochemical difference of coffee beans with different species, production areas and roasting degrees

In recent decades, the demand for coffee has seen a continuous increase, and the aroma and flavor of coffee has been widely studied. The current research chose coffee beans of two species (<i>Coffea arabica</i> and <i>C</i>. <i>canephora</i>) from five production areas (Brazil, India, Indonesia, Uganda and Vietnam) with four different roasting degrees (medium light, medium, medium dark and dark), to investigate the difference on physicochemical properties. The results showed that Arabica coffee beans had higher concentrations of fat and organic acids, and total amount of volatile compounds, whereas Robusta beans had higher concentrations of protein. With the increase of roasting degree, the concentrations of protein, fat, organic acids, and the total amount of volatile compounds of coffee beans increased, while the concentrations of chlorogenic acid compounds decreased. The discriminant analysis indicated that the tested coffee beans could be clearly discriminated by species and roasting degrees, but not by production area. The results of this research conclude the physicochemical difference of Arabica and Robusta beans with different roasting degrees. The results can provide a theoretical basis for coffee bean selection for the relevant industries.

The study of volatile compounds of the raw material of immortelle (Helichrysum bracteatum)

Topicality. Plants during their life cycle synthesize, accumulate and release volatile compounds into the environment. Volatile compounds are substances that are heterogeneous in structure and chemical properties, and belong to different classes of compounds. These substances can have saturated and unsaturated, linear and branched chains and cyclic fragments. They can also contain various functional groups: hydroxyl, ether, carboxyl, etc. Substances of the terpenes class occupy a special place among volatile compounds. Many substances related to volatile compounds are commercially important. This fact determines the commercial value of any plant and the prospects of its pharmacognostic research. The study of the composition of volatile compounds will allow us to assess the prospects of further study of a particular plant. With the steadily increasing demand of the pharmaceutical industry for the medicinal plant raw material, and the need to search for new medicinal products based on medicinal plants, special attention should be paid to plants that have a widely represented raw material base. Immortelle (Helichrysum Bracteatum) is such a promising plant. The preliminary phytochemical studies have found that the raw material of immortelle has a diverse composition of biologically active substances.Aim. To study the composition of volatile compounds of immortelle herb and flowers.Materials and methods. As the study object the crushed raw of immortelle was used. The study of volatile compounds was performed on an Agilent 6890N/5973 inert chromatography-mass spectrometric system (Agilent Technologies, USA); the carrier gas was helium.Results and discussion. As a result of the study conducted, 26 volatile compounds were identified in the herb of immortelle, 39 compounds in the flowers of immortelle. Identification was carried out using the mass spectra library NIST 02, WILEY 2007, as well as AMDIS and NIST identification programs. When determining the share of each of the substances identified in the total amount of volatile compounds it was found that the main volatile compounds in the herb of immortelle were n-hexadecanoic acid (44.48 %), phytol (13.71 %), 9.12-octadecanoic acid (11.21 %) and decamethyltetrasiloxane (8.55 %). The main volatile compounds in the flowers were n-hexadecanoic acid (43.83 %), 9.12-octadecanoic acid (19.52 %), the methyl ester of 7.10.13-hexadecatrienoic acid (8.85 %) and tetradecanoic acid (6.10 %). The remaining compounds identified were in significantly smaller amounts. Their share was 22.05 % in the herb, and 21.70 % in the flowers. Conclusions. For the first time, the study of the qualitative composition of volatile compounds in the herb and flowers of immortelle has been conducted using gas chromatography with mass spectrometric detection. The results of the study of volatile compounds of the raw material of immortelle, as well as according to the studies conducted earlier on the content of substances of other classes, indicate the prospect of further research of immortelle as an object for the development of new drugs.

A Comparative Study of Physicochemical and Flavor Characteristics of Chicken Nuggets during Air Frying and Deep Frying

AbstractChicken nuggets were air‐fried and deep‐fried for various times at the same temperature. The moisture content, oil content, color, texture, volatile compounds, and lipids degradation of the chicken nuggets were investigated. The evolution rate of the moisture content, oil content, color, and texture were much higher during deep frying than during air frying. Air frying required more time to produce similar quality attributes as those of deep‐fried chicken nuggets. On average, the oil content of the air‐fried chicken nuggets was 25% lower than that of the deep‐fried chicken nuggets. Of the 74 volatile compounds identified in the fried chicken nuggets, aldehydes, hydrocarbons, and heterocycles were the main flavor contributors. The total amount of volatile compounds and aldehydes detected in the air‐fried chicken nuggets was much lower than that in the deep‐fried samples, but the number of heterocycles produced by the Maillard reaction was higher during air frying. Sensory evaluation revealed that the air‐fried chicken nuggets had lower oiliness and crispness, and 9 min was the optimal frying time to obtain air‐fried chicken nuggets with similar sensory attributes (color, odor, juiciness, and overall acceptance) as those of the best deep‐fried chicken nuggets. Air frying was a healthier frying method for the production of fried chicken nuggets, which could reduce oxidative degradation of lipids in chicken nuggets.

Characteristics of volatile flavor components in stewed meat and meat broths prepared with repeatedly used broths containing star anise

To investigate the effects of repeatedly used broth containing star anise on the volatile flavor compounds in meat broths and stewed meat, broth containing star anise was repeatedly used to cook pork loin for 1, 2, 3, 4, 5 and 7 times, respectively. Volatile flavor profiles and compounds in meat broths were determined by sensory evaluation and identified by solid-phase microextraction combined with gas chromatography-mass spectrometry. The sensory evaluation based on a triangle test elucidated significant differences on aroma between meat broths repeatedly used for 1 time and 3 times. Moreover, a total of 37 volatile compounds were identified in meat broths cooked with star anise and the main volatile compounds were anethole, eucalyptol, linalool, terpinen-4-ol, alpha-terpineol, cedrol. The relative contents of the volatile flavor compounds in meat broths decreased as the times for the broth being reused increased. After the meat broth containing star anise being repeatedly used for 3 times, the total amount of volatile compounds was only about 50% of the initial level, and therefore, an additional 40–50% of the initial amount of star anise was recommended to add into meat broth after the broth being used 2 times. The supplementation of star anise to the meat broth helped ensure the flavor consistency of the resulted stewed meat product.

Flowering Stage and Daytime Affect Scent Emission of Malus ioensis "Prairie Rose".

Flowering crabapple is an important ornamental flower. It is vital to understand the floral scent properties and the associated release dynamics for carrying out fragrant flower breeding or floral regulation of crabapple. Static headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was used to detect the volatile compounds in Malus ioensis “Prairie Rose” flowers at different flowering stages and at different day-night time. The results showed that methylheptenone, phenylethanol, geranylacetone, 2-(4-methoxyphenyl)ethanol, α-cedrene were the major compounds in M. ioensis “Prairie Rose”, but the compounds released during different stages and different day-night time were significantly different (P < 0.0001). A total of 25 volatile compounds were identified from the four flowering stages. The floral scents in the initial and flowering stages were the most similar (dissimilarity 0.21). The main compounds in these two stages were geranylacetone and methylheptenone, and the contents of geranylacetone and phenylethanol were positively correlated with the flowering stages. From the bud stage to the end of flowering, the total amount of volatile compounds released showed an initial increase followed by a decrease and the amounts of compounds released during the initial flowering stage were the highest. The aliphatic and benzenoids content was significant higher in the daytime than at night. A total of 15 compounds were detected in the five time periods. Methylheptenone and phenylethanol were particularly released in the 10:00–12:00 and 15:00–17:00 time periods. There were only three common compounds among the five time periods and the types of flower volatiles released during the daytime were obviously higher than those released at night. From the nocturnal to diurnal, the amount of flower volatiles released first increased, then decreased, and the release reached a peak between 10 am and 12 noon, which was consistent with the pollination biological characteristics of Malus flowers. Our findings are important for understanding the mechanism of insect visits to crabapple and the regulation of crabapple flower scent.

Use of Dairy and Plant-Derived Lactobacilli as Starters for Cherry Juice Fermentation

Background: Lactic acid bacteria (LAB) exhibit a great biodiversity that can be exploited for different purposes, such as to enhance flavours or metabolize phenolic compounds. In the present study, the use of dairy and plant-derived LAB strains to perform cherry juice fermentation is reported. Methods: The growth ability of Lactobacillus plantarum, Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus was studied in cherry juice. Profiling of sugars, organic acids and volatile compounds was performed by GC-MS (Gas Chromatography-Mass Spectrometry), while the phenolic fraction was characterized using UHPLC (Ultra High Performance Liquid Chromatography) equipped with a linear ion trap-mass spectrometer. Results: Sucrose significantly decreased in all fermented samples as well as malic acid, converted to lactic acid by malolactic fermentation. The total amount of volatile compounds increased. Specifically, propyl acetate, an ester with fruit notes, reached the highest concentration in L. rhamnosus and L. paracasei (dairy strains) fermented juices. Phenolics were extensively metabolized: caffeic acid was converted into dihydrocaffeic acid, p-coumaric acid into 4-ethylphenol and phenyllactic acid was produced. Conclusion: Lactic acid fermentation confer fruit notes to the juice and enhance phenyllactic acids, especially employing dairy strains (L. rhamnosus and L. paracasei). The level of dihydrocaffeic acid, a compound with putative biological activity was also increased (in particular with L. plantarum).