Degradation of monoterpenes in orange juice by gamma radiation

Single-strength orange juice was irradiated with 0, 0.89, 2.24, 4.23, and 8.71 gGy of gamma radiation at 5 degrees C and then stored at 7 degrees C for 21 days. Volatile compounds, isolated by solid-phase microextraction, were separated and identified using a gas chromatograph equipped with a mass selective detector. The majority of the volatile compounds were terpenes, and the most abundant volatile compounds were ethanol and limonene. Most volatile compounds were stable during the 21-day storage period except geranial and neral which decreased over time. Irradiation reduced the concentration of acyclic monoterpenes, such as geranial, neral, myrcene, and linalool 1 and 7 days after irradiation, but did not affect other monoterpenes, sesquiterpenes, or other volatile compounds. The reduction of acyclic monterpenes increased linearly with radiation dose, and correlated with an increase in thiobarbituric acid reactive substrates (TBARS) content. Reduction in the concentration of monoterpenes induced by irradiation was not significant 21 days after irradiation. Our results indicate that acyclic monoterpenes are sensitive to irradiation whereas most other volatile compounds are resistant.     

Volatile monoterpenes in black currant (Ribes nigrum L.) juice: effects of heating and enzymatic treatment by beta-glucosidase

Changes of terpenes in black currant juice induced by the action of heat were investigated in the present study. Limonene, alpha-terpinene, linalool, alpha-terpineol, 4-terpineol, and menthol added to either black currant juice or a model system were thermally treated at 90 degrees C for 30 min. Similar heat-induced decreases in the concentration of the terpenes were observed in the two systems. The concentration of a range of terpene hydrocarbons and oxygenated terpenes increased, alpha-terpineol being a main conversion product of most of the examined compounds. In the main, the measured loss of compounds exceeded the detected concentrations of products formed. In addition, determination of glycosidically bound terpenes in the juice was carried out by two methods of enzymatic hydrolysis, namely, addition of beta-glucosidase to an Amberlite XAD-2 isolate or directly to black currant juice. The two methods gave the same patterns of seven released volatile aglyconic terpenes. However, none of the released terpenes are important for the odor of black currant juice.     

锦橙汁辐照和巴氏灭菌处理后相关品质的分析

为探讨辐照和巴氏杀菌对橙汁品质的影响,对锦橙汁分别进行1.4、2.8、5.6kGy3种不同剂量辐照及巴氏灭菌处理,使用固相微萃取-气质联用技术对挥发性成分进行分析,测定橙汁色度、pH值和Vc含量,并对橙汁香气进行感官评定。在鲜橙汁、巴氏灭菌汁和3种辐照样品中分别检测到了54、47、57、55和53种成分,2.8kGy剂量辐照处理后橙汁挥发性成分总峰面积最高,β-月桂烯、柠檬烯和γ-松油烯等橙汁特征香气物质经辐照后保持率高于巴氏灭菌。各种处理后Vc含量均有所下降,橙汁橙香均减弱。1.4kGy辐照后的橙汁感官评价结果最好,因此可以对橙汁进行低剂量辐照灭菌。     

High-temperature forced-air treatment alters the quantity of flavor-related, volatile constituents present in navel and Valencia oranges

A number of volatile compounds that contribute to orange flavor were quantified following high-temperature forced-air (HTFA) treatment of the fruit to determine if a relationship exists between the flavor loss that is observed following HTFA treatment and the volatile composition of the juice. Following different durations of HTFA treatment, fruit were stored for a period of 4 weeks and juiced and the juice subjected to headspace analysis using either a Tenax/Carbotrap column or a solid-phase microextraction device for trapping of the volatiles. alpha-Pinene, beta-myrcene, and limonene were reduced in amount by 60%, 58%, and 34%, respectively, over the course of the 5-h HTFA treatment. The influence of heat on the amount of decanal was less clear, although in one of the two fruit lots there was little change. The amount of ethanol was reduced by 70% after the initial hour of HTFA treatment and then steadily increased to exceed the initial amount during the remaining 4 h of the treatment. Taste evaluations of the fruit showed a reduction of flavor quality following 4 h or more of treatment. Percent acidity and soluble solids, two other very important determinants of flavor, were nearly unchanged by treatment. Alterations in the volatile constituents of oranges by HTFA treatment may be an important reason behind the negative impact of this treatment on flavor quality.     

Chemical compositions and antioxidant/anti-inflammatory activities of steam distillate from freeze-dried onion ( Allium cepa L.) sprout

Freeze-dried onion sprout was steam-distilled, and the distillate was extracted with dichloromethane (volatile sample). Water sample I was obtained from the residual aqueous solution in the extractor. The filtrate and the methanol extract of filtrand from the residual aqueous solution in the steam distillation flask were named water sample II and methanol sample, respectively. Among the total of 71 components identified in the volatile sample, 24 were sulfur-containing compounds, which comprised 36.87% of the total volatile chemicals identified. The volatile sample inhibited hexanal oxidation for 40 days by >99% at levels >100 microg/mL. The volatile sample and water sample II exhibited moderate antioxidant activity in a malonaldehyde/gas chromatography assay and thiobarbituric acid assay, whereas water sample I did not show appreciable activity. The volatile sample, water sample I, and water sample II exhibited anti-inflammatory activity with a dose-related response in the lipoxygenase inhibitor screening assay. However, the methanol sample did not show appreciable activity in either antioxidant or anti-inflammatory tests. The results suggest that onion sprouts can be an excellent food source.     

Flavor, color, and vitamin C retention of pulsed electric field processed orange juice in different packaging materials

Effects of packaging materials, storage temperature, and time on the stability of pulsed electric field (PEF) processed orange juice were investigated. Single-strength orange juice was treated with PEF at an electric field strength of 35 kV/cm for 59 micros using an integrated pilot plant scale PEF processing and glovebox packaging system. The retention of eight orange juice aroma compounds, color, and vitamin C in glass, polyethylene terephthalate (PET), high-density polyethylene, and low-density polyethylene were evaluated at 4 and 22 degrees C for 112 days. Packaging material had a significant effect (p < or = 0.05) on the retention of orange juice aroma compounds, color, and vitamin C. PEF-treated orange juice had a shelf life of >16 weeks in glass and PET at 4 degrees C.     

Effect of pH on retention of aroma compounds by beta-lactoglobulin

Interactions between volatile compounds and BLG in aqueous solution were studied using static and dynamic headspace techniques (exponential dilution). The intensity of interactions between methyl ketones (C7-C9), ethyl esters (C6-C9), limonene, myrcene, and beta-lactoglobulin (BLG) were estimated by determination of the relative infinite dilution activity coefficients (gamma(r)). For a constant pH value, the methyl ketones retention by BLG increased significantly with the hydrophobicity of the volatiles, whereas the retention reached a maximum for ethyl octanoate in the ester series, indicating a possible steric hindrance. For limonene and myrcene an unexpected increase in headspace concentration or "salting out" effect was noticed for acid pH. The variations of the retention according to the pH increase of the medium from pH 3 to pH 11 could be related to structural modifications of the BLG. The retention increase observed between pH 3 and pH 9 resulted from the flexibility modification of the protein, allowing better accessibility to the primary or the secondary hydrophobic sites, whereas the dramatic decrease observed at pH 11 was the consequence of the alkaline denaturation of BLG. Electrostatic interactions occurring at pH 7.5 could also explain the observed retention increase.     

Processing and storage effects on orange juice aroma: a review

Freshly squeezed orange juice aroma is due to a complex mixture of volatile compounds as it lacks a specific character impact compound. Fresh hand-extracted juice is unstable, and thermal processing is required to reduce enzyme and microbial activity. Heating protocols range from the lightly heated not from concentrate, NFC, to the twice heated, reconstituted from concentrate, RFC, juices. Thermal processing profoundly effects aroma composition. Aroma volatiles are further altered by subsequent time-temperature storage conditions. Heating reduces levels of reactive aroma impact compounds such as neral and geranial, and creates off-flavors or their precursors from Maillard, Strecker, and acid catalyzed hydration reactions. Off-flavors such as 4-vinylguaiacol, p-cymene, and carvone are the products of chemical reactions. Other off-flavors such as butane-2,3-dione, guaiacol, and 2,6-dichlorophenol are indicators of microbial contaminations. Since most orange juice consumed worldwide is processed, the goal of this review is to summarize the widely scattered reports on orange juice aroma differences in the three major juice products and subsequent aroma changes due to packaging, storage, and microbial contamination with special emphasis on results from GC-O studies.     

Use of 2-furoylmethyl derivatives of GABA and arginine as indicators of the initial steps of maillard reaction in orange juice

The formation of 2-furoylmethyl derivatives of GABA (2-FM-GABA) and arginine (2-FM-Arg) as early indicators of nonenzymatic browning in different types of orange juice was studied. In dehydrated orange juice, the presence of 2-FM-GABA and 2-FM-Arg was detected from the first day of storage at 30 degrees C. In this type of juice, the content of these two compounds increased with temperature (30, 50 degrees C) and time (1-7 days) of storage. A noticeable increase in 5-hydroxymethylfurfural was only observed after 4 days of storage at 50 degrees C. No formation of 2-FM-GABA and 2-FM-Arg was detected in liquid orange juice heated under conditions similar to those used in the industry. These furoylmethyl derivatives were also found in commercial orange juice made from concentrates. A slight increase in their concentration was observed in the two samples stored during 8 months at room temperature. According to the results obtained, 2-FM-GABA and 2-FM-Arg contents could be suitable indicators to assess the main modifications due to Maillard reaction produced during the manufacture and/or storage of orange juice concentrates.     

Effect of processing techniques at industrial scale on orange juice antioxidant and beneficial health compounds

Phenolic compounds, vitamin C (L-ascorbic acid and L-dehydroascorbic acid), and antioxidant capacity were evaluated in orange juices manufactured by different techniques. Five processes at industrial scale (squeezing, mild pasteurization, standard pasteurization, concentration, and freezing) used in commercial orange juice manufacturing were studied. In addition, domestic squeezing (a hand processing technique) was compared with commercial squeezing (an industrial FMC single-strength extraction) to evaluate their influences on health components of orange juice. Whole orange juice was divided into soluble and cloud fractions after centrifugation. Total and individual phenolics were analyzed in both fractions by HPLC. Commercial squeezing extracted 22% more phenolics than hand squeezing. The freezing process caused a dramatic decrease in phenolics, whereas the concentration process caused a mild precipitation of these compounds to the juice cloud. In pulp, pasteurization led to degradation of several phenolic compounds, that is, caffeic acid derivatives, vicenin 2 (apigenin 6,8-di-C-glucoside), and narirutin (5,7,4'-trihydroxyflavanone-7-rutinoside) with losses of 34.5, 30.7, and 28%, respectively. Regarding vitamin C, orange juice produced by commercial squeezing contained 25% more of this compound than domestic squeezing. Mild and standard pasteurization slightly increased the total vitamin C content as the contribution from the orange solids parts, whereas concentration and freezing did not show significant changes. The content of L-ascorbic acid provided 77-96% of the total antioxidant capacity of orange juice. Mild pasteurization, standard pasteurization, concentration, and freezing did not affect the total antioxidant capacity of juice, but they did, however, in pulp, where it was reduced by 47%.     

Uruguayan essential oil. 12. Composition of Nova and Satsuma mandarin oils

The composition of the laboratory-prepared essential oils from Uruguayan Nova and Satsuma mandarins has been studied. The volatile fraction was analyzed by HRGC and HRGC/MS (quadrupole); 79 and 73 components were identified in Nova and Satsuma mandarin oils, respectively. The linear retention indices were calculated for almost all identified components on two different stationary phases. The enantiomeric distribution of beta-pinene, sabinene, limonene, linalool, and alpha-terpineol was studied by multidimensional gaschromatography (MDGC). Polymethoxylated flavones, present in the nonvolatile residue, were analyzed by normal-phase HPLC.     

Aroma constituents and alkylamides of red and green huajiao (Zanthoxylum bungeanum and Zanthoxylum schinifolium)

Huajiao denotes the fruits of various species of Zanthoxylum in the plant family Rutaceare used for cooking. The two most commercially popular species are bungeanum (red huajiao) and schinifolium (green huajiao). Fresh huajiao has a very high content of essential oil, up to 11%, which is described as having fresh, spicy, floral, cooling, and green aroma notes. A comprehensive analysis of the essential oils by GC-MS using advanced peak deconvolution and data processing software, revealed many overlapping components. A total of 120 aroma compounds for each species has been found. In the essential oils, linalyl acetate (15%), linalool (13%), and limonene (12%) are the major components of red huajiao, whereas linalool (29%), limonene (14%), and sabinene (13%) are the major components of green huajiao. For estimation of the aroma contribution of individual components, a new concept, "aroma character impact value" (ACI), is introduced as the percentage of the ratio of the concentration of an aroma component to its odor threshold value. Despite the differences in major components, both species have six common compounds of top aroma character impact: linalool, alpha-terpineol, myrcene, 1,8-cineole, limonene, and geraniol. The tingling sensation of huajiao is caused mainly by the alkylamide hydroxy-alpha-sanshool. The tingling compound decomposes easily under hydrolytic conditions or under UV light.     

Effect of Drying Treatment Conditions on Sensory Profile of Germinated Oat

Germination and subsequent drying of oat produced significantly different sensory profiles depending on processing parameters such as drying speed and temperature profile. The most salient sensory attributes for processed oat were roasted odor and flavor, sweet taste, intense odor, intense aftertaste, and hard, crisp, brittle texture (P < 0.05). High temperatures (>85°C) were necessary to produce these sensory attributes, and quick drying after germination resulted in higher levels of intensity of favorable sensory attributes. The total amount of volatile compounds was higher in native (ungerminated) oat than in processed oat. During germination, and particularly during the drying treatment, the profile of volatile compounds changed. The most abundant volatile compounds responsible for odor were dimethyl sulfide, hexanal, pentanal, and iso butanal. The relative amount of dimethyl sulfide increased as a function of temperature in drying, whereas hexanal, pentanal, and isobutanal disappeared during heating, as did several other small ketones, alcohols, and esters. The germinated oat dried at high temperatures (65–93°C and 65–85°C) was perceived as being roasted, sweet, and nutty. Sensory and instrumental profile analyses of selected volatile compounds using partial least squares (PLS) regression techniques showed that these sensory attributes were clearly related to dimethyl sulfides and isobutanol. A moist and earthy odor was related to cymene, limonene, and isobutanal. Phenolic compounds significantly influenced oat flavor, whereas lipids had a negligible effect.     

Flavor and texture of banana chips dried by combinations of hot air, vacuum, and microwave processing

The behavior of 16 volatile compounds of banana during a combination of air-drying (AD) and vacuum microwave-drying (VMD) of banana chips was characterized. Samples were AD to remove 60, 70, 80, or 90% of moisture (wet basis) and then subjected to VMD to achieve a final moisture content of 3% (dry basis). Banana slices were also dehydrated using only AD, VMD, and freeze-drying (FD) for comparison. Samples that underwent more VMD had significantly lower levels of volatile compounds, which is attributed to the decreased formation of an impermeable solute layer on the surface of the chips. High values for water solubility and relative volatility of compounds correlated with losses during VMD; however, additional factors appear to influence the behavior of compounds during VMD processing. The optimal process of 90%AD/10%VMD yielded crisper banana chips with significantly higher volatile levels and sensory ratings than AD chips.     

Effect of ultrahigh-temperature continuous ohmic heating treatment on fresh orange juice

The scope of this study is the effect of ohmic heating thermal treatment on liquid fruit juice made of oranges. Effects of ohmic heating on the quality of orange juice were examined and compared to those of heat pasteurization at 90 degrees C for 50 s. Orange juice was treated at temperatures of 90, 120, and 150 degrees C for 1.13, 0.85, and 0.68 s in an ohmic heating system. Microbial counts showed complete inactivation of bacteria, yeast, and mold during ohmic and conventional treatments. The ohmic heating treatment reduced pectin esterase activity by 98%. The reduction in vitamin C was 15%. Ohmic-heated orange juice maintained higher amounts of the five representative flavor compounds than did heat-pasteurized juice. Sensory evaluation tests showed no difference between fresh and ohmic-heated orange juice. Thus, high-temperature ohmic-heating treatment can be effectively used to pasteurize fresh orange juice with minimal sensory deterioration.     

橙汁加工过程对农药炔螨特残留的影响

为弄清橙汁加工过程中农药炔螨特残留的动态,通过田间喷施浓度为5倍于最高推荐剂量的农药溶液以强化炔螨特在甜橙上的残留,然后按照橙汁商业化加工过程进行加工,采用QuEChERS前处理技术结合气相色谱-串联质谱法检测炔螨特的含量,来考察橙汁商业化加工过程对炔螨特残留的影响。结果表明:炔螨特残留主要分布于甜橙果皮中,果肉中炔螨特的残留量不足全果的5%。清洗能除去全果中32.5%的炔螨特残留。初榨果汁、精滤果汁、非浓缩橙汁(NFC橙汁)和浓缩橙汁中的残留量分别为原料果的1.98%、1.95%、1.73%、1.37%,其中NFC橙汁和浓缩橙汁的加工因子分别为0.0173和0.0137,但炔螨特在果渣和精油中发生富集,加工因子分别为1.2822和18.4947。研究结果为橙汁加工工艺的优化和炔螨特残留的膳食暴露评估提供参考。     

Flavor characteristics of lapsang souchong and smoked lapsang souchong, a special Chinese black tea with pine smoking process

The major volatile constituents of lapsang souchong, smoked lapsang souchong, and smoked souchong, a group of special black teas in China, were analyzed with GC and GC-MS analyses. Forty-nine constituents were identified. Longifolene and alpha-terpineol were the most abundant compounds in the aroma. Due to its special production process, the compounds longifolene, longicyclene, guaiacol, 4-methylguaiacol, 4-ethylguaiacol, etc., were identified only in this kind of black tea. The aroma constituents of tea origin decreased during the smoking process, whereas the pine terpenoids and the thermal pyrolysis products of the pine wood increased markedly. The pine material for smoking was also analyzed for the volatile constituents showing apparent selectivity of the tea leaves to absorb. There were apparent differences among the tea samples in the contents of aroma constituents. The characteristics of the aroma of the teas are discussed with their processes and the features of sensory qualities.     

Influence of thermal treatment on black currant (Ribes nigrum L.) juice aroma

The influence of thermal treatment on black currant juice aroma was investigated in temperature and time ranges relevant for black currant juice concentration processes, namely, 45, 60, 75, and 90 degrees C. Forty-nine aroma compounds were quantified, and the thermal treatment resulted in concentration increases of most terpenes, aldehydes, furans, and phenols, whereas the concentration of esters slightly decreased. Higher temperatures and longer exposure times had larger effects on the aroma compounds. Odor triangle tests showed no sensory difference between pasteurized juice and juice heated at 60 degrees C, whereas juice heated at 90 degrees C differed significantly from pasteurized juice. It is concluded that a 90 degrees C thermal treatment of black currant juice, which is in the temperature range used for conventional evaporation of black currant juice, has an effect on the aroma and sensory properties.