Citrus juice off-flavor during different processing and storage: Review of odorants, formation pathways, and analytical techniques

Characterizing and decoding the key odor-active compounds in fresh, pasteurized, and high pressure processing sea buckthorn (Hippophae rhamnoides L.) juice

The non-thermal and thermal effects on aroma of sea buckthorn juice have rarely been investigated. In this study, 57 odor compounds were identified in fresh sea buckthorn juice (FSBJ), high pressure processing sea buckthorn juice (HSBJ), and pasteurized sea buckthorn juice (PSBJ), including 29 esters, 8 aldehydes, 1 ketone, 5 alcohols, 5 acids, 6 terpenoids, and 3 others. Ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, and ethyl 2-hydroxy-3-methylbutanoate with flavor dilution factors ranging from 729 to 59,049 contributed to the fruity odors of FSBJ and HSBJ. Besides, the formation of off-odor compounds including hexanal, nonanal, furfural, 3-methylbutanoic acid, and dimethyl disulfide with odor activity values ≥ 1, imparts fatty, roasted, sweaty, and cooked odor in PSBJ. The variations of vitamin C and reducing sugar are significantly associated with changes in odor-active compounds during pasteurized processing. These findings provide new insights that high pressure processing minimizes the adverse effects of pasteurization.

Volatile profiles of Murcott and Ponkan mandarins obtained by stir bar sorptive extraction technique and their contributions to the fruit aroma

Citrus species have undergone immense diversification ever since their ancestral origin. Ponkan and Murcott are two mandarin varieties widely consumed in Brazil and their aroma producing active compounds have not yet been extensively investigated. The present study analyzed the volatile constituents of the Ponkan and Murcott varieties employing the stir bar sorptive extraction (SBSE) technique and gas chromatography-mass spectrometry (GC-MS) analysis for the first time. Extraction was performed using the two phases of Twister bar, polydimethyl siloxane (PDMS), and ethylene glycol (EG) silicone in immersion and headspace modes. Among the detected 62 compounds comprising alcohols, aldehydes, esters, terpenes, and others identified, 55 and 37 compounds in the Ponkan and Murcott variety were determined, respectively, from both immersion and headspace modes using the two phases of Twister bar. From the odor active values, the Ponkan was characterized with the domination of compounds such as hexanal, decanal, nonanal, (E)-2-hexanal, ethyl hexanoate, d-limonene, linalool, and geraniol. Similarly, the Murcott variety was characterized with predominant compounds, namely, nonanal, octanal, hexanal, (E)-2-hexanal, ethyl hexanoate, d-limonene, and linalool. The profile of volatile compounds was found to be unique in both the varieties studied, and SBSE technique with GC-MS analysis favored the characterization of their respective profile due to the high amount of phase in the Twister bars, when compared to similar techniques, like solid phase microextraction. The PDMS Twister bar showed better capacity of adsorption of volatile compounds, since it is a relatively low-polarity polymer, which discriminates less analytes with different structures and polarities sampled from complex matrices, such as fruits juice.

Characterization of volatile compounds from healthy and citrus black spot-infected Valencia orange juice and essential oil by using gas chromatography-mass spectrometry

Citrus black spot (Phyllosticta citricarpa, CBS) is an important fungal disease that causes rind blemishes and affects quality of citrus fruits. The response of citrus to CBS in terms of volatiles was evaluated using molecular sensory science approaches. Fifty and twenty-one volatiles were identified in the orange juice and essential oil samples, respectively, via gas chromatography-mass spectrometry (GC-MS). The total volatile content in the samples increased after CBS infection, especially in the severe-infection group (SEG) juice and moderate-infection group (MOG) essential oil, which reached the highest levels. CBS enhanced floral, fruity, and off-flavor aromas and decreased the green aroma in citrus juice. Citrusy, floral, and green aromas increased in the CBS-infected essential oil. Six/five potential markers were screened in citrus juice/essential oil, respectively using the orthogonal partial least-square discriminant analysis (OPLS-DA) model. The changes in aroma profile and the difference in infection levels in citrus were attributed to these odorants.

Delivery systems designed to enhance stability and suitability of lipophilic bioactive compounds in food processing: A review

Lipophilic compounds, such as flavors, fat-soluble vitamins, and hydrophobic nutrients possess vital properties including antioxidant effects, functional attributes, and nutritional value that can improve human health. However, their susceptibility to environmental factors including heat, pH changes, and ionic strength encountered during food processing poses significant challenges. To address these issues, diverse bioactive delivery systems have been developed. This review explores delivery systems designed to optimize the stability and suitability of lipophilic bioactive compounds in food processing. Extensive literature analysis reveals that tailoring delivery systems with various biopolymers can protect bioactives through steric hindrance and formation of thick interfacial layers on the emulsion surfaces. Thus, the access of oxygen, prooxidants, and free radicals at the emulsion interface could be inhibited, resulting in enhanced processing suitability of bioactives as well as chemical stability under diverse environmental conditions. The insights presented in this review hold immense value for the food and beverage industries.

The effects of different extraction methods on essential oils from orange and tangor: From the peel to the essential oil

Citrus fruits are largely consumed due to their unique and pleasant aromas. Citrus hybrids have been developed to enhance their flavors and bioactivities. Citrus aroma depends on the composition of the volatile compounds in citrus essential oils (CEOs), which are mostly located in the peels. During the extraction of CEOs, a specific series of chemical reactions occurred depending on the extraction methods (CP, cold pressing; HD, hydrodistillation), leading to variations in the composition of volatile compounds. In this study, the orange and the tangor which is a hybrid between C. reticulata × C. sinensis were investigated to compare the changes in volatile compounds based on the extraction methods. Results showed that the CP-specific volatile compounds were sesquiterpenes, oxygenated monoterpenes, and fatty acid derivatives, while the HD-specific volatile compounds were terpinyl cation derivatives, limonene, and 4-vinylguaiacol. On the other hand, the contents of some volatile compounds ((E)-ocimene, α-terpinene, and α-terpinolene) were affected by the Citrus species rather than by the extraction methods. In particular, during HD, terpinene-4-ol and 4-vinylguiacol, known as off-flavor compounds in citrus juice, were formed more abundantly in the orange than in the tangor. In conclusion, these results provide comprehensive data on essential oils, especially those derived from oranges and tangors, for selecting the appropriate extraction method for obtaining a higher yield and quality of citrus flavor.

Effects of irradiation on the aging and sensory quality of navel orange distilled spirits

BACKGROUND

60 Co-γ irradiation can simulate the effects of aging and enhance the flavor of distilled spirits. The present study aimed to investigate the effects of 0, 2, 4, 6, 8 and 10 kGy 60 Co-γ irradiation doses on the key aroma components in newly produced navel orange distilled spirits and thus determine the mechanism of their aging distilled spirits.

RESULTS

The identification of aroma compounds demonstrated that ethyl hexanoate, d-limonene, ethyl octanoate, 3-methyl-1-butanol and linalool are the key aroma compounds in navel orange distilled spirits, which were increased except for linalool with irradiation doses of 2-6 kGy. Irradiation treatment simulated the effects of the aging of navel orange distilled spirits by promoting the content of total acids, total esters and aldehydes. Irradiation doses of 2-6 kGy increased the aroma intensity of navel orange distilled spirits, reaching an optimum at 6 kGy. However, irradiation doses as high as 8 and 10 kGy decreased the content of esters in navel orange distilled spirits, which led to a deterioration of the spirit flavor.

CONCLUSION

Low doses of 60 Co-γ irradiation can simulate the effects of the aging by increasing the content of key aromatic compounds in navel orange distilled spirits. © 2023 Society of Chemical Industry.

Association between dietary flavonoid intake and depressive symptoms: A cross-sectional research

OBJECTIVE

To investigate the relationship between dietary flavonoid intake and depression symptoms in American adults.

METHODS

Data sets were obtained from the National Health and Nutrition Examination Survey (NHANES) 2007-2008, 2009-2010, and 2017-2018 survey cycles. Both males and females aged 18 years and older with complete information about dietary flavonoid intake (isoflavones, anthocyanidins, flavan-3-ols, flavanones, flavones, and flavonols), depression symptoms, and covariates were included. Logistic regression models were conducted to calculate the odds ratio (OR) of single dietary flavonoid subclass intake on depression, and the restricted cubic spline (RCS) models were utilized to explore the corresponding dose-response relationships. Additionally, we implemented the weighted quantile sum (WQS) regression and quantile g-computation (qgcomp) models to estimate the mixed effects of six flavonoid subclasses and identify the predominant types.

RESULTS

After multivariable adjustments, people with higher consumption of flavanones (OR: 0.68, 95% CI: 0.52-0.90, p = 0.008), flavones (OR: 0.63, 95% CI: 0.46-0.87, p = 0.007), flavonols (OR: 0.66, 95% CI: 0.49-0.89, p = 0.008), and total flavonoids (OR: 0.69, 95% CI: 0.50-0.95, p = 0.024) had lower odds of depression symptoms. Meanwhile, significant dose-response relationships were supported by the RCS models. However, no obvious associations between isoflavones, anthocyanidins, flavan-3-ols, and the odds of suffering from depression symptoms were found by the logistic regression models and RCS models. As for the mixed effect, the WQS and qgcomp models both demonstrated that the mixture of six flavonoid subclasses was inversely related to the odds ratios of depression symptoms, and flavones, flavanones, and anthocyanidins were the top 3 contributors.

CONCLUSION

Our study implied dietary flavonoid intake was associated with the decreased probability of depression symptoms in U.S. adults, among which flavones, flavanones, and anthocyanidins may occupy the predominant roles.

Evaluation of Active LDPE Films for Packaging of Fresh Orange Juice

Microbial development, enzymatic action, and chemical reactions influence the quality of untreated natural orange juice, compromising its organoleptic characteristics and causing nutritional value loss. Active low-density polyethylene (LDPE) films containing green tea extract (GTE) were previously prepared by a blown film extrusion process. Small bags were prepared from the produced films, which were then filled with fresh orange juice and stored at 4 °C. Ascorbic acid (AA) content, sugar content, browning index, color parameters, pH, total acidity (TA) and microbial stability were evaluated after 3, 7, and 14 days of storage. The packaging containing GTE maintained the microbial load of fresh juice beneath the limit of microbial shelf-life (6 log CFU/mL) for the bacterial growth, with a more prominent effect for LDPE with 3%GTE. Regarding yeasts and molds, only the CO_LDPE_3GTE package maintained the microbial load of fresh juice below the limit for up to 14 days. At 14 days, the lowest levels of AA degradation (32.60 mg/100 mL of juice) and development of brown pigments (browning index = 0.139) were observed for the packages containing 3% of GTE, which had a pH of 3.87 and sugar content of 11.4 g/100 mL of juice at this time. Therefore, active LDPE films containing 3% of GTE increase the shelf-life of fresh juice and can be a promising option for storage of this food product while increasing sustainability.