Coffee brewing sonoreactor for reducing the time of cold brew from several hours to minutes while maintaining sensory attributes

This research designed and developed an ultrasonic reactor for a fast and on demand production of cold brew coffee, remarkably reducing the brewing time from 24 h to less than 3 min. The technology was engineered by utilizing resonance to induce ultrasonic waves around the walls of the brewing basket of an espresso machine. The sound transmission system comprised a transducer, a horn and a brewing basket. This arrangement transformed the coffee basket into an effective sonoreactor that injected sound waves at multiple points through its walls, thereby generating multiple regions for acoustic cavitation within the reactor. Furthermore, acoustic streaming induced greater mixing and enhanced mass transfer during brewing. The design was accomplished by modeling the transmission of sound, and acoustic cavitation. Brew characterization and chemical composition analysis was performed, considering factors such as pH, acidity, color, and the composition of caffeine, fatty acids, and volatiles. The efficiency of the extraction increased by decreasing the basket loading percentage (BLP). For instance, sonicating at 100 W doubled the extraction yield and caffeine concentration, from 15.05 % to 33.44 % at BLP = 33 %, and from 0.91 mg/mL to 1.84 mg/mL at BLP = 67 %, respectively. The total fatty acids increased from 1.16 mg/mL to 9.20 mg/mL, representing an eightfold increase, at BLP = 33 %. Finally, a sensory analysis was conducted to evaluate appearance, aroma, texture, flavor, and aftertaste, which demonstrated that coffee brewed for 1 and 3 min in the sonoreactor exhibited almost undistinguishable properties compared to a standard 24 h brewing without ultrasound.

Bringing back a forgotten legume-Sensory profiles of Australian native wattleseeds reveal potential for novel food applications

Documented as one of the oldest living civilizations, there is now evidence that Indigenous communities in Australia followed a sustainable lifestyle with well-designed agricultural practices and adequate physical activity. Commonly known as wattleseeds in Australia, unique cultivars of Acacia have been consumed by Indigenous Australians for over 60,000 years. This research used descriptive sensory profiling to develop a lexicon for the aroma and flavor profiles of four wattleseed species before and after being subjected to different processing techniques. The processing methods selected were pressure cooking, dry roasting, wet roasting, and malting. The species included were Acacia kempeana, Acacia adsurgens, Acacia colei, and Acacia victoriae. Sensory differences were observed between the different cultivars as well as between the different food processing techniques. Results show that wattleseed species diversity is a key driver in determining the aroma profile, while taste profiles are modified by the type of processing method applied. PRACTICAL APPLICATION: This study provides foundational knowledge on these culturally significant seeds, supporting practical opportunities to diversify the uses of wattleseeds in food products.

Astringency and its sub-qualities: a review of astringency mechanisms and methods for measuring saliva lubrication

Astringency is an important mouthfeel attribute that influences the sensory experiences of many food and beverage products. While salivary lubricity loss and increased oral friction were previously believed to be the only astringency mechanisms, recent research has demonstrated that nontactile oral receptors can trigger astringency by responding to astringents without mechanical stimulation. Various human factors have also been identified that affect individual responses to astringents. This article presents a critical review of the key research milestones contributing to the current understanding of astringency mechanisms and the instrumental approaches used to quantify perceived astringency intensity. Although various chemical assays or physical measures mimic in-mouth processes involved in astringent mouthfeel, this review highlights how one chemical or physical approach can only provide a single measure of astringency determined by a specific mechanism. Subsequently, using a single measurement to predict astringency perception is overly idealistic. Astringency has not been quantified beyond the loss of saliva lubrication; therefore, nontactile receptor-based responses must also be explored. An important question remains about whether astringency is a single perception or involves distinct sub-qualities such as pucker, drying, and roughness. Although these sub-quality lexicons have been frequently cited, most studies currently view astringency as a single perception rather than dividing it into sub-qualities and investigating the potentially independent mechanisms of each. Addressing these knowledge gaps should be an important priority for future research.

Chemical composition of bunya nuts (Araucaria bidwillii) compared to Araucaria angustifolia and Araucaria araucana species

Three of nineteen Araucaria tree species from around the world produce large edible seeds. While composition is established for edible pinhão and piñones nuts from Brazil and Chile, respectively, the first detailed characterisation for the composition of edible Araucaria bidwillii (bunya nut) from Australia is provided. Almost half of the kernel weight is moisture and the main component in the dried kernel is starch. Whilst low in protein and fat, it contains all essential amino acids and half the fatty acids are polyunsaturated (Omega-3 and 6). Bunya nuts are a source of dietary fibre, folate and minerals (Cu, Mn, Fe, Mg), while the nut husks and inner coating are high in phenolics, mainly catechin. The composition supports the Traditional Knowledge of Aboriginal Australians that the bunya nut is an energy dense and nutrient rich food. Similarities in the composition among the three different edible varieties were found, which should assist in developing sustainable value chain propositions via shared knowledge on processing and utilisation.

Holistic approach to effects of foods, human physiology, and psychology on food intake and appetite (satiation & satiety)

Appetite (satiation and satiety) is an essential element for the control of eating behavior, and as a consequence human nutrition, body weight, and chronic disease risk. A better understanding of appetite mechanisms is necessary to modulate eating behavior and food intake, and also provide a practical approach for weight management. Although many researchers have investigated the relationships between satiation/satiety and specific factors including human physiology, psychology, and food characteristics, limited information on the interactions between factors or comparisons between the relative importance of factors in contributing to satiation/satiety have been reported. This article reviews progress and gaps in understanding individual attributes contributing to perceived satiation/satiety, the advantages of considering multiple factors together in appetite experiments, as well as the applications of nondestructive sensing in evaluating human factors contributing to relative appetite perception. The approaches proposed position characterization of appetite (satiation and satiety) for personalized and precision nutrition in relation to human status and healthy diets. In particular, it is recommended that future studies of appetite perception recognize the inter-dependence of food type and intake, appetite (satiation and satiety), and individual status.

Folate vitamers in the Australian green plum: Through growth and ripening and across locations

The green plum is a native fruit of Australia that grows on the tree Buchanania obovata. This study aimed to confirm the high level of folate in green plums by analyzing a large number of ripe samples from multiple locations and to understand how folate vitamers change as the fruit grows through maturity stages. This study analyzed green plums for five vitamers of folate, H4folate, 5-CH3-H4folate, 5-CHO-H4folate, 10-CHO-PteGlu, and PteGlu (folic acid) using a stable isotope dilution assay on a liquid chromatograph mass spectrometer (LC-MS). Green plums were tested from four locations, two harvests and five maturity stages. Another 11 ripe samples, each from different tree clumps from one location, were also tested as were ripe red-colored green plums. The results show the 5-CH3-H4folate in green plum increases and accumulates in the fruit through development, ripening and senescence. The ripe green plums contain between 82.4 ± 5.5 and 149.4 ± 10.7 μg/100 g Fresh Weight (FW). The red-colored green plums are even higher in folate, with total folate measured as 192.5 ± 7.0 and 293.7 ± 27.4 μg/100 g FW, and further analysis of them is suggested. There is some variation in amounts of folate between fruit from different locations and sets of trees, but all ripe green plums tested are considered good dietary sources of folate.

Sensory properties of Australian bunya nuts

Abstract

Bunya nuts are the seeds of Araucaria bidwillii, a conifer native to South‐East Queensland, Australia. They are one of the 19 species of Araucaria family found around the world, with the nuts from South America being the most commonly consumed. They are traditionally eaten boiled or roasted. This study aims to profile the sensory properties of bunya nuts with chestnut as a comparator. Since chestnuts do not come from a conifer tree, it is expected that there will be differences. Different methods of preparation are also expected to change the sensory attributes. Representative samples were collected from a variety of locations in South‐East Queensland, prepared and presented to a panel of 14 experienced tasters applying conventional sensory descriptive profiling.

Practical Application

There is an increase demand for local, sustainable, and natural foods. Bunya nuts are native to Australia and are part of the Araucaria family, which includes 19 species that can be found around the world. To the best of our knowledge there is no study characterizing Araucaria nuts in terms of sensory attributes. This study builds a lexicon for bunya nuts and compares to chestnuts. It also shows how different preparation methods affect its sensory attributes, as well as possible future uses in product development. The outcomes might provide information to support studies on Araucaria nuts in other countries.

Integrating Effects of Human Physiology, Psychology, and Individual Variations on Satiety–An Exploratory Study

Satiety can influence food intake, and as a consequence has the potential to affect weight and obesity. Human factors such as physiology and psychology are likely to be important in determining satiety. However, it is not well-understood how these factors (individual variations) alone or combined contribute to satiety feelings. In addition, there have been limited or no attempts to use a holistic approach to evaluate satiety. In this study, three plant-based foods were used as mid-morning snack for 52 participants to evaluate satiety response (during three consecutive days, one-day-one-food type). The foods were served ad libitum until participants felt comfortably full prior to satiety monitoring. The study explored diverse human factors (n = 30) that might contribute to satiety including those related to oral physiology, metabolic factors, body composition and psychology. It identified important variables for satiety as well as the interactions among them and the influences of age, gender, and low satiety phenotype (consistently lower reported fullness scores) on satiety. Overall, combinations of factors rather than individual ones contributed to self-reported satiety. Food factors (e.g., type, composition) had limited effects, but there were only three types used in the study. The combination of metabolic factors [respiratory quotient, age, and body energy usage type (e.g., carbohydrate or fat)], oral sensitivity & processing, personality traits (agreeableness, conscientiousness, and neuroticism), and eating behavior (e.g., emotional and external eating) were the most important for explaining individual satiety responses. Older participants had significantly higher reported satiety than younger participants, associated with significant differences in oral physiology, increased body fat, and mature psychological characters. Moreover, different satiety phenotypes had significant differences in relationships with body fat, oral physiology, personalities, food neophobia, and eating behaviors. The results of this study indicate that much greater insights into the factors determining satiety responses can be obtained by combining multiple food and human physiological and psychological characteristics. This study used more diverse measures of individual variation than previous studies of satiety and points the way toward a more holistic approach to understanding the (control of) perceptions of fullness at both individual and group levels.

A preliminary study on the utilisation of near infrared spectroscopy to predict age and in vivo human metabolism

The objective of this study was to evaluate the ability of a portable near infrared (NIR) instrument to analyse different tissues in healthy individuals in vivo and relate the spectral data with age, resting metabolic rate (RMR), respiratory quotient (RQ), body fat (BF) and body mass index (BMI). A NIR (950-1600 nm) instrument was used to collect the spectra of different tissues and partial least squares (PLS) regression was used to relate the NIR with RMR, RQ, BF and BMI. Results shown that non-destructive techniques such as those based in vibrational spectroscopy have potential to be used as tools to better categorise and understand the complex inter-individual differences that determine interactions between physiology and nutrition.

The Framework for Responsible Research With Australian Native Plant Foods: A Food Chemist's Perspective

Australia is a rich source of biodiverse native plants that are mostly unstudied by western food science despite many of them being ethnofoods of Australian Indigenous people. Finding and understanding the relevant policy and legal requirements to scientifically assess these plants in a responsible way is a major challenge for food scientists. This work aims to give an overview of what the legal and policy framework is in relation to food chemistry on Australian native plant foods, to clarify the relationships between the guidelines, laws, policies and ethics and to discuss some of the challenges they present in food chemistry. This work provides the framework of Indigenous rights, international treaties, federal and state laws and ethical guidelines including key legislation and guidelines. It discusses the specific areas that are applicable to food chemistry: the collection of plant foods, the analysis of the samples and working with Indigenous communities. This brief perspective presents a framework that can be utilized by food chemists when developing responsible research involving plant foods native to northern Australia and can help them understand some of the complexity of working in this research area.

Insights on the role of chemometrics and vibrational spectroscopy in fruit metabolite analysis

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The use of vibrational spectroscopy combined with data analytics is discussed.

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The measure of bioactive compounds metabolites in fruit samples is presented.

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Advantages and limitations of these techniques are discussed.

The last three decades have demonstrated the ability of combining data analytics (e.g. big data, machine learning) with modern analytical instrumental techniques such as vibrational spectroscopy (VIBSPEC) (e.g. NIR, Raman, MIR) and sensing technologies (e.g. electronic noses and tongues, colorimetric sensors) to analyse, measure and monitor a wide range of properties and samples. Developments in instrumentation, hardware and software have placed VIBSPEC as a useful tool to quantify several bioactive compounds and metabolites in a wide range of fruit and plant samples. With the incorporation of hand-held and portable instrumentation, these techniques have been valuable for the development of in-field and high throughput applications, opened new frontiers of analysis in fruits and plants. This review will present and discuss some of the current applications on the use of VIBSPEC techniques combined with data analytics on the measurement bioactive compounds and plant metabolites in different fruit samples.

Towards personalised saliva spectral fingerprints: Comparison of mid infrared spectra of dried and whole saliva samples

The aims of this study were to compare two sample presentations (dry and whole) as well as the effects of both gender and age on the mid infrared (MIR) fingerprint spectra of human saliva. Unstimulated saliva was collected from 52 Female (31 subjects, aged 40.9 ± 14.6 year) and Male (21 subjects, aged 34 ± 11.8 year) participants, stored frozen, and subsequently thawed and analysed by MIR spectroscopy as whole and dried saliva, respectively. Data were analysed by means of principal components analysis (PCA) and partial least squares (PLS) to interpret and compare the effects of presentation (dry vs whole), age and gender on the MIR spectra of saliva. Interpretation of the MIR spectra of both whole and dried samples revealed specific characteristic and different spectral signals when gender and age were compared in the amide I and amide II of proteins (e.g. albumin) and DNA. While whole saliva analysis might be more convenient for rapid test, dried saliva spectra were more consistent across replicates, demonstrating greater ability to distinguish individual differences. The interpretation of the PCA and PLS loadings of both whole and dried saliva samples allowed identification of specific MIR regions associated with age and gender of participants between 1000 cm^-1 and 1800 cm^-1. In particular, the MIR regions associated with the absorption of polysaccharides, glycosylated proteins, and nucleic acid phosphate groups present in saliva were the most dominant. This paper demonstrates that MIR spectroscopy can be used to measure saliva samples and to interpret individual differences in participants due to age in either dry or whole samples. No clear trends were observed in the MIR spectra of the samples associated with gender when all samples were analysed together. However, PLS regression models were able to predict gender in a subset of samples having similar age. The approach described in this study shows promise for potentially using saliva as a tool in food studies (e.g. saliva interactions between food and consumers).

Challenges and opportunities of the fourth revolution: a brief insight into the future of food

By 2050, the global population is projected to be in excess of nine billion people. This will result in an increased burden and stress on the food production systems, particularly in adjustments to several stages of the value chain that will require improvements and/or modifications in their effectiveness such as reducing waste, adapting to climate change, food security, and health. Disruptions such as digital agriculture, digital food, food agility, big data, have been utilized to characterize the changes in the way agro-food systems evolve and function, as well as in the approach they have been analyzed, measured, and monitored. It has been long recognized that the food industry is considered as a data driven enterprise. These characteristics are very important as the food industry becomes global and sustainable. The food industry is currently undergoing significant changes, and with this, challenges are occurring. These challenges are brought about from the food chains, climate changes, and the ability to be resilient in the production of food. Furthermore, health and cultural changes to food are occurring, where the diseases of obesity, diabetes, and aging in the population will continue to change the consumer's patterns and choices; whereby the consumer will be persuaded to choose and eat healthy and more nutritious foods. Indeed, the cultural awareness and social innovation to prevent food waste and therefore improve food security and sustainability will also prove to further complexities. This short review will briefly discuss some of the forefront issues in food value chains with a focus on using technology.

A Difficult Pill to Swallow: An Investigation of the Factors Associated with Medication Swallowing Difficulties

BACKGROUND

Many medications are available as solid oral dosage forms such as tablets and capsules; however, some people find these medications difficult to swallow.

AIM

To identify whether certain psychological, oral sensory, and oral motor characteristics contribute to medication swallowing difficulties.

METHODS

A sample of healthy adults from two academic institutions in Brisbane were assessed for their experiences with swallowing solid oral dosage forms, food preferences, and food neophobia. The gag reflex, oral cavity size, fungiform papillae count, and chewing efficacy were also evaluated followed by a capsule-swallowing task. Primary outcome was the incidence of medication swallowing difficulties. Secondary outcomes were the association of medication swallowing difficulties with psychological, oral sensory, and oral motor factors.

RESULTS

Of 152 subjects, 32% reported difficulty swallowing tablets or capsules whole. This group was significantly more likely to have had a memory of choking on medications compared to those without medication swallowing difficulties (OR = 7.25, p < 0.05). Current medication swallowing difficulties were significantly associated with a smaller mouth cavity size (OR = 2.98, p < 0.05), a higher density of taste receptors on the tongue (OR = 3.27, p < 0.05), and were higher among those who chewed a jelly candy to non-homogenous particle size (OR = 4.1, p < 0.05). Current medication swallowing difficulties were associated with lower confidence in swallowing large capsules (000 size: OR = 0.47, 00 size: OR = 0.39, p < 0.05). No associations were found between medication swallowing difficulties and the gag reflex or food neophobia.

CONCLUSION

A combination of heightened oral perception characterized by a small oral cavity and high taste sensitivity compounded by a past choking episode on medications may be precipitating factors for medication swallowing difficulties. These factors may be helpful in identifying individuals who are more likely to experience difficulty swallowing medications.

The Nutritional Potential of the Native Australian Green Plum (Buchanania obovata) Compared to Other Anacardiaceae Fruit and Nuts

The native Australian green plum (Buchanania obovata) is a small fruit that grows in the northern parts of the Northern Territory and Western Australia. The fruit belongs to the family Anacardiaceae, which includes the other agriculturally important fruit mangoes, pistachios and cashew nuts. The green plum is a favored species of fruit for the Aboriginal communities and an important bush food in the Northern Territory. To date, only minimal scientific studies have been performed on the green plum as a food. This review is about plant foods in the family Anacardiaceae and the key nutritional compounds that occur in these fruit and nuts. It looks at the more traditional nutrient profiles, some key health metabolites, allergens and anti-nutrients that occur, and the role these foods play in the health of populations. This provides a guide for future studies of the green plum to show what nutritional and anti-nutritional properties and compounds should be analyzed and if there are areas where future studies should focus. This review includes an update on studies and analysis of the green plum and how its nutritional properties give it potential as a food for diet diversification in Australia.

Feeding unsaleable carrots to lambs increased performance and carcass characteristics while maintaining meat quality

This study investigated the effect of feeding unsaleable carrots to lambs within a total-mixed ration (TMR) on performance, carcass characteristics, meat quality and sensory parameters. Thirty-six Australian Merino wether lambs were fed a control (barley-based) or carrot-based TMR for 11-weeks. Carrot-fed lambs had 2.7% higher cold dressing percentage (P = 0.03) while consuming less than control lambs. Subcutaneous fat of carrot-fed lambs contained less branch-chained, and more cis- and trans-monounsaturated fatty acids (FA; P ≤ 0.01) compared to control-fed lambs, which tended (P = 0.08) to have higher concentrations of polyunsaturated FA, despite the Longissimus lumborum (LL) muscle being unchanged by diet. Under retail display conditions, L* and hue values were lower (P ≤ 0.04) for 5 d aged LL samples from carrot-fed lambs. No differences were observed in other meat quality and sensory parameters between diets. Therefore, feeding unsaleable carrots at 45% DM in a TMR can improve lamb performance and carcass characteristics, while maintaining meat quality and FA composition.

Slower development of lower canopy beans produces better coffee

The production of high-quality coffee is being challenged by changing climates in coffee-growing regions. The coffee beans from the upper and lower canopy at different development stages of the same plants were analyzed to investigate the impact of the microenvironment on gene expression and coffee quality. Compared with coffee beans from the upper canopy, lower canopy beans displayed more intense aroma with higher caffeine, trigonelline, and sucrose contents, associated with greater gene expression in the representative metabolic pathways. Global gene expression indicated a longer ripening in the lower canopy, resulting from higher expression of genes relating to growth inhibition and suppression of chlorophyll degradation during early bean ripening. Selection of genotypes or environments that enhance expression of the genes slowing bean development may produce higher quality coffee beans, allowing coffee production in a broader range of available future environments.

Overall Nutritional and Sensory Profile of Different Species of Australian Wattle Seeds (Acacia spp.): Potential Food Sources in the Arid Semi-Arid Regions

Wattle seed (Acacia spp.) is a well-known staple food within indigenous communities in Australia. A detailed investigation of the overall nutritional and sensory profile of four abundant and underutilized Acacia species-A. coriacea, A. cowleana, A. retinodes and A. sophorae-were performed. Additionally, molecular weight of protein extracts from the wattle seeds (WS) was determined. The seeds are rich in protein (23-27%) and dietary fibre (33-41%). Relatively high fat content was found in A. cowleana (19.3%), A. sophorae (14.8%) and A. retinodes (16.4%) with oleic acid being the predominant fatty acid. The seeds contained high amounts of essential amino acids (histidine, lysine, valine, isoleucine and leucine). A. coriacea is rich in iron (43 mg/kg), potassium (10 g/kg) and magnesium (1.7 g/kg). Pentose (xylose/arabinose), glucose, galactose and galacturonic acids were the major sugars found in the four species. Raw seeds from A. sophorae, A. retinodes and A. coriacea have the highest protein molecular weight, between 50-90 kDa, 80 kDa and 50-55 kDa, respectively. There was variation in the sensory profile of the WS species. This study showed that the four WS species have good nutritional value and could be included in human diet or used in food formulations.

Diurnal Harvest Cycle and Sap Composition Affect Under-Skin Browning in 'Honey Gold' Mango Fruit

Under-skin browning (USB) is an unsightly physiological disorder that afflicts 'Honey Gold' mango fruit. Under-skin browning symptoms develop after harvest upon the interaction of physical abrasion and physiological chilling stresses. Less understood preharvest and/or harvest factors may also influence fruit susceptibility to USB. In this study, we examined the impact of harvest time during the diurnal cycle and fruit sap components on USB development. Fruits were harvested at 4- to 6-h intervals, lightly abraded with sandpaper to simulate vibration damage during refrigerated road transport, held at 12 ± 1°C for 6 days, transported to the research facilities and ripened before USB assessment. Spurt and ooze sap from the fruit were collected at each harvest time. The samples were separated and analysed by gas chromatography-mass spectrometry. Fruit harvested at 10:00, 14:00 and 18:00 h had 3- to 5-fold higher incidence of USB than did those picked at 22:00, 2:00 and 6:00 h. Sap concentrations of the key aroma volatile compounds 2-carene, 3-carene, α-terpinene, p-cymene, limonene and α-terpinolene were higher for fruit harvested at 14:00 h compared to those picked at other times. In the fruits harvested in the afternoon, abraded skin treated with spurt sap sampled at 14:00 h had 14.3- and 29.0-fold higher incidence and severity, respectively, of induced browning than did those treated with sap collected at 6:00 h. The results showed that fruit harvested in the afternoon were more susceptible to USB than those picked at night or in early morning. The diurnal variation in fruit sensitivity was evidently associated with specific compositional differences in sap phytotoxicity. Topical application to the fruit skin of pure terpinolene and limonene resulted in induced USB damage, whereas pure carene and distilled water did not. Microscopy examination showed that while skin damage caused by pure terpinolene and limonene was not identical to USB per se, similarities suggested that sap components cause USB under inductive commercial conditions. Considered collectively, these findings suggest that night and early morning harvesting will reduce USB and thus improve the postharvest quality of Honey Gold mango fruit.

Effect of natural antioxidants on lipid oxidation in mayonnaise compared with BHA, the industry standard

INTRODUCTION

Mayonnaise is an oil in water emulsion (O/W) consisting 70-80% oil. Lipid oxidation is a major cause of quality deterioration in mayonnaise. The effectiveness of antioxidants in a hetrophasic systems is highly dependent on their polarity and partitioning properties.

OBJECTIVES

The aim of the present study was to determine the effect of a hydrophilic [green tea extract (GTE)] and a lipophilic [tocopherol mixture (TOC)] and BHA on lipid oxidation in mayonnaise during 60 days of storage at 38 °C and to examine the interactions between GTE and TOC, to determine possible synergistic or antagonistic effects in antioxidant activity.

METHODS

The oxidative stability was studied by measuring hydroperoxides, volatile organic compounds (VOCs) and colour of mayonnaise during storage. Comprehensive analysis of VOCs was done by static headspace extraction and separation by two-dimensional gas chromatography time of flight mass spectrometry. Sensory analysis was also carried out to study the effect of storage time and antioxidant type on sensory properties of mayonnaise and to investigate the predictive ability of volatile compounds for sensory terms.

RESULTS AND CONCLUSION

Addition of GTE (500 ppm) and TOC (500 ppm) increased the formation of hydroperoxides and certain VOCs. The combination of GTE with TOC improved the antioxidant efficacy compared to the individual extracts. However, sensory evaluation demonstrated that GTE promoted the development of unpleasant fishy and rancid aroma. The volatile compound methional, was significantly and positively correlated with fishy and rancid flavour. Regarding colour analysis, GTE showed the highest increase in darkening and browning during storage.

Comprehensive profiling of lipid oxidation volatile compounds during storage of mayonnaise

Lipid oxidation is a primary cause of quality deterioration in mayonnaise that leads to a decrease in the nutritional and sensorial value. The evolution of volatile oxidation compounds in sunflower oil mayonnaise stored at varying temperatures for 92 days and the antioxidative effect of butylated hydroxyanisole were investigated by static headspace extraction and separation by two dimensional gas chromatography/time-of-flight mass spectrometry. Considerable differences in the headspace composition of samples stored at 4, 25 and 38 °C were found due to the different oxidation levels reached. The content of hexanal in mayonnaise at 1-5 days of storage at 38 °C could be used to predict the corresponding compound in mayonnaise at 1-62 days of storage at 25 °C. The 10 most important discriminating volatile compounds during lipid oxidation of mayonnaise (at 38 °C for 92 days) are 3-hexenal, pentanal, 2-heptenal, 2-ethylfuran, hexanal, benzeneacetaldehyde, 2-pentylfuran, 3-methylhexane, 1-pentanol and 2,4-heptadienal. More than half of these compounds have a close relationship with the initial content of linoleic acid that agrees with the fatty acid profile of sunflower oil (~ 70% linoleic acid). These volatiles could be used as additional markers of oxidation in sunflower oil mayonnaise.

Texture and mouthfeel perceptions of a model beverage system containing soluble and insoluble oat bran fibres

Dietary fibre fortified products have increased in popularity as health-conscious consumers seek convenient ways to increase fibre intake. Fibres from wholegrains are particularly desirable inclusions in food products because of their proven physiological health-benefits. When fortifying beverages with fibre, however, the insoluble dietary fibre components present in wholegrains often contribute to unpleasant gritty sensations making the products unpalatable. Consequently, designing wholegrain-fortified beverages with sufficient fibre-content to make health related fibre claims is a major challenge in the food manufacturing industry. This work aims to take a systematic approach in identifying the texture/mouthfeel related sensory impact and interaction between two commercial oat fibre ingredients (Oatwell28XF® and Milled Oats) when added to a model beverage system. Eighteen samples were prepared containing either or both the ingredients, at varying levels, and were assessed by a trained panel using conventional sensory descriptive techniques. The results indicate that the two different oat bran fibres produced distinct mouthfeel perceptions which could be attributed to the varying soluble and insoluble fibre content of the samples. Insoluble dietary fibre concentrations above 2% (w/w) resulted in particle-related sensory properties chalkiness, dryness and particle perception, which dominated the overall mouthfeel and textural sensory perception of the samples. Samples with predominantly soluble β-glucan, resulted in perceptions of smoothness, sliminess and stickiness residue, while thickness, mouthcoating and cloying sensations were driven by total fibre concentration, irrespective of fibre solubility. This work provides a solid foundation for food manufacturers aiming to rationally design and develop nutritionally superior fibre-fortified beverages and is relevant to fibre content concentrations required for labelling/nutrition claims for consumer products in many developed nations.

Stable isotope dilution assay (SIDA) and HS-SPME-GCMS quantification of key aroma volatiles for fruit and sap of Australian mango cultivars

Reported herein is a high throughput method to quantify in a single analysis the key volatiles that contribute to the aroma of commercially significant mango cultivars grown in Australia. The method constitutes stable isotope dilution analysis (SIDA) in conjunction with headspace (HS) solid-phase microextraction (SPME) coupled with gas-chromatography mass spectrometry (GCMS). Deuterium labelled analogues of the target analytes were either purchased commercially or synthesised for use as internal standards. Seven volatiles, hexanal, 3-carene, α-terpinene, p-cymene, limonene, α-terpinolene and ethyl octanoate, were targeted. The resulting calibration functions had determination coefficients (R²) ranging from 0.93775 to 0.99741. High recovery efficiencies for spiked mango samples were also achieved. The method was applied to identify the key aroma volatile compounds produced by 'Kensington Pride' and 'B74' mango fruit and by 'Honey Gold' mango sap. This method represents a marked improvement over current methods for detecting and measuring concentrations of mango fruit and sap volatiles.

Increase in β-ionone, a carotenoid-derived volatile in zeaxanthin-biofortified sweet corn

Carotenoids are responsible for the yellow color of sweet corn (Zea mays var. saccharata), but are also potentially the source of flavor compounds from the cleavage of carotenoid molecules. The carotenoid-derived volatile, β-ionone, was identified in both standard yellow sweet corn ('Hybrix5') and a zeaxanthin-enhanced experimental variety ('HZ') designed for sufferers of macular degeneration. As β-ionone is highly perceivable at extremely low concentration by humans, it was important to confirm if alterations in carotenoid profile may also affect flavor volatiles. The concentration of β-ionone was most strongly correlated (R(2) > 0.94) with the β-arm carotenoids, β-carotene, β-cryptoxanthin, and zeaxanthin, and to a lesser degree (R(2) = 0.90) with the α-arm carotenoid, zeinoxanthin. No correlation existed with either lutein (R(2) = 0.06) or antheraxanthin (R(2) = 0.10). Delaying harvest of cobs resulted in a significant increase of both carotenoid and β-ionone concentrations, producing a 6-fold increase of β-ionone in 'HZ' and a 2-fold increase in 'Hybrix5', reaching a maximum of 62 μg/kg FW and 24 μg/kg FW, respectively.

The formation of wine lactone from grape-derived secondary metabolites

Wine lactone (i.e., 3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one, 1a/1b) was formed hydrolytically at wine pH from both racemic (E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid (3) and the corresponding glucose ester 2a at 45 °C but at room temperature was only formed from the acid 3. The glucose ester does not appear to be a significant precursor for the formation of wine lactone in wine. The slow formation of wine lactone from the free acid 3 indicates that the acid is not likely to be an important precursor to wine lactone in young wines unless present in high concentration (≫ 1 mg/L), but could be a significant precursor to wine lactone in wine that is several years old. The wine lactone formed in hydrolysates of the (6R)-enantiomer of 3 was partially enriched in the (3S,3aS,7aR)-enantiomer 1a when the hydrolysis was conducted at pH 3.2 and 100 °C in a closed vessel or under simultaneous distillation-extraction (SDE) conditions, and the enantiomeric excess (ee) varied from 5 to 22%. Hydrolysis of (6R)-3 in sealed ampules at 45 °C and at pH 3.0, 3.2, or 3.4 gave near-racemic wine lactone, but when the hydrolyses were conducted at room temperature, the product was enriched in the (3S,3aS,7aR)-enantiomer 1a and the ee was greater at higher pH (up to 60% at pH 3.4).

Improved approach for analyzing bromophenols in seafood using stable isotope dilution analysis in combination with SPME

An analytical method for the measurement of five naturally occurring bromophenols of sensory relevance in seafood (barramundi and prawns) is presented. The method combines simultaneous distillation-extraction followed by alkaline back extraction of a hexane extract and subsequent acetylation of the bromophenols. Analysis of the bromophenol acetates was accomplished by headspace solid phase microextraction and gas chromatography-mass spectrometry using selected ion monitoring. The addition of (13)C 6 bromophenol stable isotope internal standards for each of the five congeners studied permitted the accurate quantitation of 2-bromophenol, 4-bromophenol, 2,6-dibromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol down to a limit of quantification of 0.05 ng/g of fish flesh. The method indicated acceptable precision and repeatability and excellent linearity over the typical concentration range of these compounds in seafood (0.5-50 ng/g). The analytical method was applied to determine the concentration of bromophenols in a range of farmed and wild barramundi and prawns and was also used to monitor bromophenol uptake in a pilot feeding trial.

Usefulness of chemometrics and mass spectrometry-based electronic nose to classify Australian white wines by their varietal origin

A combination of mass spectrometry-based electronic nose (MS e_nose) and chemometrics was explored to classify two Australian white wines according to their varietal origin namely Riesling and unwooded Chardonnay. The MS e_nose data were analysed using principal components analysis (PCA), discriminant partial least squares (DPLS) and linear discriminant analysis (LDA) applied to principal components scores and validated using full cross validation (leave one out). DPLS gave the highest levels of correct classification for both varieties (>90%). LDA classified correctly 73% of unwooded Chardonnay and 82% of Riesling wines. Even though the conventional analysis provides fundamental information about the volatile compounds present in the wine, the MS e_nose method has a series of advantages over conventional analytical techniques due to simplicity of the sample-preparation and reduced time of analysis and might be considered as a more convenient choice for routine process control in an industrial environment. The work reported here is a feasibility study and requires further development with considerably more commercial samples of different varieties. Further studies are needed in order to improve the calibration specificity, accuracy and robustness, and to extend the discrimination to other wine varieties or blends.

Stable isotope dilution analysis of wine fermentation products by HS-SPME-GC-MS

The aim of this study was to quantify, in a single analysis, 31 volatile fermentation-derived products that contribute to the aroma of red and white wine. We developed a multi-component method based on headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS). The 31 volatile compounds analysed include ethyl esters, acetates, acids and alcohols. Although these compounds have a range of functional groups, chemical properties, volatilities, affinities for the SPME fibre, and are found in wine at various concentrations, the accuracy of the analysis was achieved with the use of polydeuterated internal standards for stable isotope dilution analyses (SIDA). Nine of the labelled standards were commercially available, while 22 were synthesised. The method was validated by a series of duplicate spiked standard additions to model, white and red wine matrices over the concentration range relevant for each compound in wine. This demonstrated that the appropriate use of SIDA helped to account for matrix effects, for instance potential sources of variation such as the relative response to the MS detector, ionic strength, ethanol content and pH of different wine matrices. The resultant calibration functions had correlation coefficients (R(2)) ranging from 0.995 to 1.000. Each compound could be quantified at levels below its aroma threshold in wine. Relative standard deviations were all <5%. The method was optimised for the best compromise (over the 31 compounds) of wine dilution factor, level of sodium chloride addition, SPME fibre, SPME temperature, SPME time, GC column and MS conditions. Confirmation of identity was achieved by retention time and peak shape, and measurement of at least three ions for each analyte and internal standard with the MS operating in selected ion monitoring mode to facilitate more precise quantitation with a high sampling rate. The method is a valuable research tool with many relevant applications. A novel method for the combined chiral separation and SIDA quantification of 2- and 3-methylbutanoic acid is also demonstrated.