Pectinesterase extraction from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels

Extracts from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels were tested for their pectinesterase activity. A factorial design was applied in this study as a method for enzyme extraction in which the variables were the source of enzyme (prickly pear and Mexican lime peels) and the NaCl solution concentration (0–3.0 M). In all cases, enzyme extracts obtained using the same NaCl concentration from lime peel showed higher activity than extracts from prickly pear peel. NaCl concentration influenced the pectinesterase extraction process in both cases. Maximum enzyme activities were obtained with NaCl 0.5 M and 1.0 M for Mexican lime and prickly pear peels, respectively.     

Effect of oral administration of water-soluble extract from citrus peel (Citrus unshiu) on suppressing alcohol-induced fatty liver in rats

Water-soluble citrus peel extract (WCE) from Citrus unshiu was studied for its anti-alcoholic fatty liver activities through chronic oral administration to Sprague Dawley (SD) rats. WCE, which was prepared by ultrasound-assisted extraction (UAE), was co-supplemented with ethanol (2.87 ml/rat/day) at low and high dosages (278 and 576 mg/rat/day, respectively) for 6 weeks. Ethanol consumption significantly elevated both total cholesterol (TC) and triglyceride (TG) concentrations in the serum of SD rats; otherwise co-administration of WCE lowered both serum TG and TC levels. Ethanol consumption caused a hepatic lipid content of 227 mg/g liver after 6 weeks whereas co-administration of WCE, especially at high dosage, significantly reduced it to 187 mg/g of liver. Analysis of hepatic fatty acids revealed that WCE suppressed conjugation of oleic acid into TG. These results support probable application of WCE as an anti-alcoholic fatty liver agent.     

PET trays coated with Citrus extract exhibit antioxidant activity with cooked turkey meat

A natural Citrus extract with potential antioxidant activity was evaluated as an ingredient for the production of active food packaging. The extract, in methanol, was sprayed onto the surface of polyethylene terephthalate (PET) trays. For comparison, a second set of trays were prepared using α-tocopherol as the coating. The effectiveness of the two types of packaging in delaying lipid oxidation in cooked turkey meat slices, stored at 4 °C over 4 days, was compared using 2-thiobarbituric acid-reactive substances (TBARS) and hexanal assays. TBARS and hexanal values, for meat stored on the Citrus extract coated trays, were significantly lower (P < 0.01) than those of meat stored on uncoated (control) trays while α-tocopherol coated trays exhibited no significant effect compared to control trays (P > 0.05). The effectiveness of the Citrus extract coating, compared to the α-tocopherol coating, was attributed to its higher surface roughness, demonstrated by optical profilometry, and the higher level of release (solubility) of the antioxidant in water.     

Essential Oils of New Pigmented Citrus Hybrids: Citrus sinensis L. Osbeck x C clementina Hort. ex Tanaka

The chemical composition of the essential oils of 2 new pigmented Citrus hybrids (Omo‐6 and Omo‐12) was studied by gas chromatography‐mass spectrometry (GC‐MS). The hybrids were obtained by crossbreeding the orange Citrus sinensis (L.) Osbeck cultivar‘Moro’ and clementine Citrus clementina Hort. ex Tanaka cultivar‘Oroval’. Seventy‐eight components were fully characterized and grouped in five classes (monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpenes, aliphatic alcohols and ethers, and aliphatic aldehydes) for an easier comparison of the oils with parents and those of 2 previously analyzed hybrids (Omo‐15 and Omo‐31) from the same crossbreeding procedure.     

改进型Clevenger装置提取柠檬果皮精油及成分分析

研究Clevenger装置改进前后对尤力克柠檬精油提取率和精油成分的影响;采用改进型Clevenger装置分别提取了青柠、尤力克、艾伦尤力克、费米耐劳、无籽里斯本5个不同柠檬品种的果皮精油,通过气相色谱-质谱法对其进行成分分析和结构鉴定,得到不同品种的柠檬果皮精油成分的指纹图谱。结果表明,Clevenger装置改进后尤力克柠檬精油的提取率增加了63.37%,且对精油挥发性成分种类无显著影响;5个柠檬品种中分别检测到51、50、41、43种和42种挥发性成分,主要为烯烃类、醇类、醛类、酯类以及少量的酸类和酮类。烯烃类物质是各个品种精油成分中最主要的组分,其中特征香气成分D-柠檬烯相对含量最高,β-蒎烯、γ-松油烯次之。品种间差异较大,除了含有32个共有成分之外,每个品种都存在自身特有的挥发性成分。     

Qualitative and nutraceutical aspects of lemon fruits grown on the mountainsides of the Mount Etna: A first step for a protected designation of origin or protected geographical indication application of the brand name ‘Limone dell'Etna’

The cultivation of lemon (Citrus limon (L.) Burm f.) has occurred for centuries at the mountainsides of the Mount Etna the largest active volcano in Europe (Sicily, Italy). The peculiar geographical, soil and climatic conditions that characterize this area have recently prompted citrus growers to launch the brand name ‘Limone dell'Etna’ for the lemon fruits produced in that area. The present research focused on evaluating the quality and nutraceutical properties of the ‘Limone dell'Etna’ fruit juice (‘Primofiore’, ‘Bianchetto’, and ‘Verdello’ blooming) to enhance the value of a product that, due to its peculiar qualities, could be awarded with one of the European certified labels protecting the lemon geographical origin. Qualitative parameters, health-promoting components (such as ascorbic acid, flavonoids, and hydroxycinnamic acids) and the in-vitro total antioxidant capacity (ORAC, FCR) of fruit juice of two different varieties (‘Femminello zagara bianca’ and ‘Monachello’) were determined at fruit maturity. The results showed that the Bianchetto and Verdello lemon fruit exhibited higher levels of ascorbic acid than those recorded for the Primofiore production. The amount of flavonoids in Verdello fruits of both cultivars was the highest, as was reflected in the highest antioxidant activity. Thus, the ‘Limone dell'Etna’ production, with particular reference to the Verdello fruit, must be considered as a new, valuable and original source of natural antioxidants to be valorized and even exploited in the processing industry.     

Learning to associate compatible and incompatible pictures with food and non-food odours,within a stimulus equivalence paradigm

Within consumer research, it is acknowledged that influential and perhaps unconscious associations to products exist, which require indirect as well as direct methods of investigation. We examine the potential usefulness of one such indirect method, an application of the stimulus equivalence matching-to-sample paradigm [Sidman, M. (1971). Reading and auditory–visual equivalences. Journal of Speech and Hearing Research, 14, 5–13].Two experiments are reported (n = 15, n = 20). Both used three, 3-membered stimulus sets: A (food and non-food odours); B (nonsense syllables); and C (pictures), two of which were either ‘compatible’ or ‘incompatible’ with the corresponding items in the A set. Each participant took part in both ‘compatible’ and ‘incompatible’ conditions. First, (A → B), participants were trained to choose one of the three nonsense syllables when presented with one of the odours. Second, (B → C), those who had learned the first task (n = 10, n = 14) were trained to choose one of the three pictures when presented with one of the nonsense syllables, and finally, in a test phase (C → A), to choose one of the three odours when presented with one of the pictures. In both experiments, B → C trials to criterion and response times were significantly greater in the ‘incompatible’ condition, and the error structure differed between conditions. In other phases, no consistent inter-condition differences were found. We discuss the use of this paradigm in consumer research on odours and tastes as a very indirect way of measuring pre-existing associations.     

Mandarin preservation by microwave-powered cold plasma treatment

Cold plasma treatment (CPT) was investigated as a nonthermal method for inhibiting Penicillium italicum and improving storability of mandarins (Citrus unshiu Marc.). Whole mandarin fruits or the peels were treated with cold plasma at 0.7 kPa using a microwave CPT system. The treatment variables were plasma-forming gases, plasma generation power, and treatment time. Nitrogen (N₂)-CPT at 900 W for 10 min, resulted in the highest inhibition of P. italicum (84% reduction in disease incidence), significantly increased the total phenolic content and antioxidant activity of mandarin peel after the treatment (p < 0.05), but did not significantly affect CO₂ generation, weight loss, content of soluble solids, titratable acidity, pH, ascorbic acid concentration (flesh), or surface color during storage at 4 and 25 °C. These results demonstrate the potential for CPT application as a postharvest technology for preserving mandarins, increasing the total phenolic content and antioxidant activity of mandarin peel.     

What are domestic apples worth? Hedonic responses and sensory information as drivers of willingness to pay

The effects of written information of key sensory characteristics of apple cultivars on hedonic ratings and willingness to pay (WTP) were measured in an experimental auction. Participants (n = 118, 95F, 23M, mean age 37 y.) rated, in three subsequent rounds, pleasantness and WTP based on (1) appearance only (n = 25), (2) appearance, written information and tasting (n = 44), or (3) appearance, tasting and written information (n = 49). Four domestic cultivars were described as medium sour and crispy (‘Amorosa’), sour and medium crispy (‘Konsta’), medium sweet and medium crispy (‘Lobo’) and sweet and medium crispy (‘Tobias’). The differences between the cultivars in pleasantness and WTP were minimal when the evaluation was based on appearance only. The effect of tasting after visual inspection was positive in three cultivars and negative in one (‘Konsta’). Written information after tasting did not affect pleasantness or WTP. For one cultivar (‘Tobias’), information given before tasting created expectations that were not fulfilled, thus tasting decreased hedonic ratings and WTP. Mean WTP was 2.36 euro/kg. When pleasantness increased by one point, WTP increased by 0.31–0.45 euro/kg. Regression models showed that pleasantness explained 38–55% of WTP. Respondents who reported consuming domestic apples more often than once a week had 0.52–0.74 euro/kg higher WTP than those who consumed them less frequently, suggesting that familiarity with the product increases WTP. Results indicate that both written information and tasting contribute to the ratings of pleasantness and WTP.     

Antioxidant activity and effective compounds of immature calamondin peel

The antioxidant activity and the flavonoids of mature and immature calamondin (Citrus mitis Blanco) peel were investigated. The hot water extract of immature calamondin peel exhibited the highest oxygen radical absorbance capacity (ORAC), reducing power, and superoxide scavenging effect. 3′,5′-Di-C-β-glucopyranosylphloretin, naringin, hesperidin, nobiletin, and tangeretin are the five major flavonoids found in hot water extract with the levels of 6888 ± 522, 2333 ± 157, 1350 ± 94, 165 ± 13, and 8 ± 4 mg/100 g dry basis, respectively. The contents of nobiletin and tangeretin increased after ripening. The hot water extract of immature calamondin peel was fractionated using a semi-preparative HPLC. Fraction VI showed the highest ORAC value (28.02 ± 2.73 mmol Trolox equivalents (TE)/g fraction) and two compounds, naringin and hesperidin, were identified as the major active components attributed to the antioxidant activity. Fraction V contained 3′,5′-di-C-β-glucopyranosylphloretin, which revealed low ORAC value with 7.43 mmol TE/g fraction. However, it might also contribute to antioxidant activity in immature calamondin peel due to its greatest quantity.     

Hepatoprotection using sweet orange peel and its bioactive compound,hesperidin, for CCl4-induced liver injury in vivo

The hepatoprotective effect of water extracts of sweet orange (Citrus sinensis) peel (WESP) and its biological compound, hesperidin (HD), on oxidative stress in vivo, were investigated. HD was the major compounds among the ten compounds identified using HPLC-DAD and HPLC-MS/MS analysis. Oral administration of WESP to rats at 10 and 100 mg/kg bw for 28 consecutive days before a single dose of CCl₄ (2 ml/kg bw) demonstrates a significant protective effect by lowering the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and by improving the histological architecture of the rat liver. WESP attenuated oxidative stress by increasing the content of hepatic glutathione (GSH), and by a dramatic increase in the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). WESP induced a significant CYP2E1 activity, which suggests that WESP may be a substrate of CYP2E1. WESP at a dose of 1.0 mg/kg bw and HD at 0.1 mg/kg bw did not sustain the protective effect against oxidative stress, in vivo. This study demonstrated that citrus peel protects rat liver from CCl₄-induced injury by attenuating hepatic oxidative stress, which suggests that WESP can be used as a therapeutic antihepatotoxic agent for the treatment of hepatic injury.     

The ripening influence of two papaya cultivars on carotenoid biosynthesis and radical scavenging capacity

Carotenoid biosynthesis in papaya fruits from the cultivars (cv.) ‘Golden’ and ‘Sunrise Solo’ was studied throughout three different ripening stages. The content of these secondary metabolites was assessed using HPLC–PDA–MSⁿ. Carotenoid levels increased during ripening, with all-trans-lycopene varying from 0.73 to 1.58 μg/g in the cv. ‘Golden’ and from 0.68 to 1.67 μg/g in the cv. ‘Sunrise Solo’. The all-trans-β-cryptoxanthin content varied from 1.29 to 3.0 μg/g in the cv. ‘Golden’ and from 0.28 to 5.13 μg/g in the cv. ‘Sunrise Solo’. The Zds gene showed a different pattern of expression during the ripening and between cultivars, while the Lcyβ gene expression was up-regulated in the two cultivars. The capacity to scavenge peroxyl radicals did not show a significant difference among the ripening stages and between the different cultivars. This study describes, for the first time, a tentative correlation between carotenoid biosynthesis in papaya pulp and the gene expression of the enzymes related to this pathway.     

Comparative performance of the nine-point hedonic,hybrid and self-adjusting scales in the generation of internal preference maps

This study evaluated the performance of the nine-point hedonic, hybrid and self-adjusting scales in the segmentation of samples and consumers using MDPREF methodology. Overall acceptability of eight Cabernet Sauvignon red wines was evaluated by 112 consumers using the three scales mentioned above. Both the scale’s and the sample’s presentation order were balanced among the consumers. The data were analyzed by ANOVA, REGWQ test, MDPREF and permutation tests. Scales’ performance was judged using the following criteria: number of significant dimensions (p = 5%) in the MDPREF, number of significantly fitted consumers (p = 5%) and segmentation of the products and consumers. The MDPREF generated by the hybrid scale data produced the greatest number of significant dimensions (p = 5%), yielding 79.5% of significantly fitted consumers (p = 5%), while the MDPREFs of the self-adjusting and the nine-point scales fitted 54.5% and 51.8% of the consumers, respectively. Overall, the results indicated superiority of the hybrid scale over the traditional hedonic and self-adjusting scales.     

Assessment of the Variations in Selected Industrially Desirable Morphological and Biochemical Traits of Eleven Citrus Species in Sri Lanka

The fruits with nutraceutical and medicinal values are having a greater significance in modern food industry. Out of many fruit tree bearing genera, the genus Citrus is extremely important in this regard. It contains well known species such as orange, lime, mandarin, lemon and many other underutilized species. The nutritive value of Citrus is given by many bioactive compounds present in the fruits such as alkaloids, tannins, phenols and saponins. In Sri Lanka, the available Citrus germplasm is not characterized in detail. Especially underutilized Citrus species are yet to receive a proper taxonomic identity. Therefore in the present study we report some of the important morphological and biochemical traits of eleven Citrus species. The fruit size traits; weight, height and width were very highly variable among the studied genotypes and positively correlated to each other (P<0.05). However, juice volume was not highly correlated with the other fruit size traits. The juice volume per unit fruit weight can be given as a better indicator for the selection of these species for industrial applications. Pummelo, a popular edible Citrus fruit, showed the lowest volume to weight ratio of 0.06. The size of the endocarp cells (i.e. juice sacks) was also very highly variable among genotypes / species studied. The brix value, a parameter of total soluble solids, was highest in Sidaran fruits (8.07%) and lowest in cooking types such as lemon and lime (3.27% and 3.76% respectively). Similarly the ascorbic acid concentration was also lowest in lime and lemon (1.9 and 1.5 mM respectively). The sweet orange cultivar Sisila (5.9 mM) and Pummelo (6.9 mM) had the highest ascorbic acid concentrations. The results reported here are very useful to select these genotypes / species for potential industrial applications, future genetic and breeding studies and to further characterize at molecular level to establish an accurate taxonomic scheme for Sri Lankan Citrus germplasm which will be the next focus of our group.     

Initial liking influences the development of acceptance learning across repeated exposure to fruit juices in 9–11 year-old children

In several studies, it has been found that repeated exposure to a novel food increases children’s acceptance of the exposure food. The present study, investigated how repeated exposure influences the acceptance of two Nordic berry juices, and whether the development depends on initial liking of the product, in 9–11 year-old children. The study had 317 participants. Two groups of children were exposed to either sea-buckthorn (n = 92) or aronia (n = 105) juice eight times, and performed two follow-up sessions 3 and 6 months after the 8th exposure. A third group (n = 120) served as controls. During pre and post-test sessions all participating children evaluated acceptance of both juices.Intake of sea-buckthorn juice increased significantly over the eight exposures (55.1 ± 7.3 till 108.8 ± 12.3) and remained high after 6 months (131.1 ± 13.2). Intake of aronia juice was only increased at follow-up sessions. Liking did not develop significantly for any of the juices across exposures. When children were grouped by their initial liking increased intake across exposures was observed regardless of initial liking of sea-buckthorn. Liking developed similarly for both juices. A significant increase was found for the ‘initial dislikers’ only. This study demonstrates how exposure effects are influenced by initial liking; it appears that changes in familiarity explain the changes seen for sea-buckthorn among ‘dislikers’. ‘Initial dislikers’ had the most benefit from repeated exposures, but did not reach ‘initial likers’ across eight exposures; more exposures in the group of ‘initial dislikers’ had possibly led to even higher liking and intake. The increased intake observed for ‘neutral likers’ and ‘initial likers’ of sea-buckthorn was not explained by increased familiarity or increased liking.     

Investigating the control of Listeria monocytogenes on alternatively-cured frankfurters using natural antimicrobial ingredients or post-lethality interventions

The objective of this study was to investigate natural antimicrobials including cranberry powder, dried vinegar and lemon juice/vinegar concentrate, and post-lethality interventions (lauric arginate, octanoic acid, thermal treatment and high hydrostatic pressure) for the control of Listeria monocytogenes on alternatively-cured frankfurters. Lauric arginate, octanoic acid, and high hydrostatic pressure (400 MPa) reduced L. monocytogenes populations by 2.28, 2.03, and 1.88 log10 CFU per g compared to the control. L. monocytogenes grew in all post-lethality intervention treatments, except after a 600 MPa high hydrostatic pressure treatment for 4 min. Cranberry powder did not inhibit the growth of L. monocytogenes, while a dried vinegar and a vinegar/lemon juice concentrate did. This study demonstrated the bactericidal properties of high hydrostatic pressure, octanoic acid and lauric arginate, and the bacteriostatic potential of natural antimicrobial ingredients such as dried vinegar and vinegar/lemon juice concentrate against L. monocytogenes.     

Influence of different shrinking temperatures and vacuum conditions on the ability of psychrotrophic Clostridium to cause ‘blown pack’ spoilage in chilled vacuum-packaged beef

This study determined the ability of psychrotrophic Clostridium strains isolated from vacuum-packaged beefs and abattoir environments to cause ‘blown-pack’ spoilage of vacuum-packaged beef stored at 2 and 15 °C. The influence of shrinking temperatures (83, 84 and 87 °C) and vacuum pressure (6 and 9 mbar) on the occurrence of such spoilage as well as the effects of simulated transportation (500 km) on the integrity of packages was determined. At 15 °C and 2 °C, twelve and six strains caused ‘blown-pack’ spoilage, respectively. The combination of vacuum pressure (9 mbar) combined with shrinking temperature (87 °C) retarded the occurrence of spoilage. The simulated transportation under the experimental conditions did not affect the integrity of packages. More studies that assess the factors that may contribute for the occurrence of ‘blown-pack’ spoilage should be performed to avoid the occurrence of such spoilage during its shelf-life.     

Perception of flavour in standardised fruit pulps with additions of acids or sugars

We hypothesised that adding sugars or acids to pulps derived from fruit of different genetic background, or of lower or higher carbohydrate status should give similar results until a threshold for sweetness or acidity perception in the pulp background was reached. Pulps made from fruit of Actinidia deliciosa ‘Hayward’—a fresh sweet-acid kiwifruit—and A. chinensis ‘Hort16A’—a sweet tropical flavoured kiwifruit, were compared. Flavour volatiles and background sugar and acid composition differed between the two fruit. Using high (14.1–14.5%) or low (11.5–11.9%) soluble solids (SS) pulps, trained tasters perceived added sugar as sweeter, confirming earlier research with consumers. Added acids (7 mmoles H⁺ 100 g⁻¹) reduced perceptions of sweetness and tasters perceived quinic acid to have a strong impact on the pulps tasted, resulting in a greater perception of acidity than addition of citric, ascorbic or malic acids. However perceptions of acidity also depended on background pulp composition. Addition of sugar or acid to pulps affected measured headspace volatiles. Volatile compounds affected included mid-chain length aldehydes, alcohols and esters, but only a few showed significant alteration. For example, hexanal, (E)-3-hexen-1-ol and (Z)-3-hexenol increased significantly when malic acid was added to ‘Hayward’ pulps. We suggest that the release of alcohols was associated with change in acidity and pulp metabolism rather than a ‘salting out’ effect. Perceived changes to banana and lemon flavours with both sugar and acid addition appear to be due to interactions in taster mouths or associated memories rather than release of specific volatiles.     

Caffeic acid derivatives in dried Lamiaceae and Echinacea purpurea products

The concentrations of caffeic acid derivatives within Lamiaceae and Echinacea (herb, spice, tea, and dietary supplement forms) readily available in the US marketplace (n = 72) were determined. After the first identification of chicoric acid in Ocimum basilicum (basil), the extent to which chicoric acid could be found within the family Lamiaceae was investigated. The dominant phenolic acid in all Lamiaceae samples was rosmarinic acid, which ranged from 2.04 mg/100 g (one of 12 oregano samples) to 622.28 mg/100 g (lemon balm). Of the herbs tested in this study (marjoram, oregano, peppermint, rosemary, sage, spearmint, and thyme from the family Lamiaceae), only basil and lemon balm (Melissa officinalis) contained chicoric acid. Basil samples (starting material and resulting end product) obtained from an industry cooperator, showed substantial phenolic deficiency as a result of processing (approximately 78% loss).     

Sensory characterisation of food and beverage stimuli containing β-ionone and differences between individuals by genotype for rs6591536

The aroma compound β-ionone is present in many fruits and vegetables and their derived products. Odour profiles at different β-ionone concentrations and perceived contributions of β-ionone to food/beverage flavour have only been partially established, and they generally do not extend to differences among individuals who vary in their sensitivity to the odour. Recent research has identified rs6591536, a single nucleotide polymorphism (SNP) located in the coding region of the odorant receptor OR5A1 as responsible for major differences in ability to detect β-ionone odour. In Study 1, using trained sensory panellists (n = 12), odour profiles were obtained for a range of β-ionone concentrations and compared across sensitivity groups defined by genotypes for rs5691536 (GG/AG or AA). A similar comparative approach was used in Studies 2 and 3, where participants (n = 104 and 158) characterised food/beverage stimuli containing added β-ionone using check-all-that-apply questions. The concentration of β-ionone required to elicit perception of the ‘floral’, ‘rose/violet’ and ‘aromatic/fragrant’ characteristics typically associated with β-ionone depended on the background fruit flavour (apple, raspberry, orange) and/or the product type (juice, jelly). It also differed among people classified as more sensitive (“sensitive”) and more insensitive (“insensitive”) to the odour of β-ionone. Perception of negative aspects of β-ionone (incl. ‘sour, acid, vinegar’, ‘sharp, pungent’, ‘soap’, ‘chemical’, ‘artificial’, ‘aftertaste’, ‘woody’) was encountered in all studies, but with varying frequency depending on concentration of added β-ionone and whether participants were “sensitive” or “insensitive” to β-ionone. There was some evidence in Study 3 that perception of β-ionone flavour was masked by the fruity flavours of the test products and that changes in ‘sweet’ and ‘fruity’ were associated with β-ionone spike concentration. Overall, this research suggests a need to consider genotype-encoded sensitivity together with other variables when measuring human flavour perception.