Equilibrium headspace analysis of volatile flavor compounds extracted from soursop (Annona muricata) using solid-phase microextraction

The influence of headspace solid-phase microextraction (HS-SPME) variables, namely, sample concentration, salt concentration and sample amount, on the equilibrium headspace analysis of the main volatile flavor compounds released from soursop was investigated. A total of 35 volatile compounds, comprising 19 esters, six alcohols, three terpenes, two acids, two aromatics, two ketones and an aldehyde, were identified. The results indicated that all response-surface models were significantly (p < 0.05) fitted for 10 target volatile flavor compounds. The results further indicated that more than 65% of the variation in the equilibrium headspace concentrations of target volatile flavor compounds could be explained by the final reduced models, with high R² values ranging from 0.658 to 0.944. Multiple optimization results showed that extraction using a 76.6% (w/w) sample concentration, 20.2% (w/w) salt and 8.2 g of blended soursop pulp was predicted to provide the highest overall equilibrium headspace concentration for the target soursop volatile flavor compounds.     

Storage stability,color kinetics and morphology of spray-dried soursop (Annona muricata L.) powder: effect of anticaking agents

Soursop is a tropical fruit that undergoes postharvest deterioration rapidly. Conversion into powder is an ave nue to value-add the fruit as it helps to reduce postharvest losses. Although powder production is not complicated, studies have shown that caking is a common problem often associated with fruit powders. Thus, an addition of a food additive is needed to improve the storage stability of powders. In this study, soursop powder was produced by spray-drying an enzyme-liquefied soursop puree incorporated with either tricalcium phosphate (TCP) or calcium silicate (CS), at three different concentrations (0.5, 1.0, and 1.5% w/w). The control was considered powder without the addition of anticaking agent. Storage stability of the powder packed in aluminum-laminated polyethylene (ALP) pouches was examined at conventional (25 ± 1°C) and accelerated (38 ± 1°C) temperatures for 91 days until lumpiness was observed. Statistical analysis showed that the addition of anticaking agent significantly (p ≤ 0.05) improved the process yield of powder (7.2%). The moisture content, water activity, density, and water solubility index of the powder were significantly affected by storage time, storage temperature, and concentration of the anticaking agents. The critical moisture content, X_c, for control and powder incorporated with either TCP or CS was 0.07 g H₂O/g ds. The total color difference (ΔE) of the powder increased throughout the storage period, followed by a zero-order kinetic reaction. Kinetics-derived Arrhenius model showed that the activation energy (Ea) of color change ranged between 6.5 and 17.3 kJ/mol. Scanning electron microscopy showed that the freshly spray-dried powder was composed of spherical particles with smooth surfaces but these particles tended to agglomerate and form liquid bridges after storage for 91 days. Overall, TCP and CS exhibited a protective effect by lowering moisture adsorption and improved the glass transition temperature of the powder.     

利用顶空固相微萃取联动气相色谱-质谱分析对比分析刺果番荔枝和普通番荔枝的挥发性香气成分

目的比较普通番荔枝(Annonasquamosal)与刺果番荔枝(Annonamuricata)挥发性香气成分上的差异。方法本研究利用顶空固态微萃取(headspace-solid phase microextraction, HS-SPME)方法吸附收集样品挥发性香气成分,通过色谱-质谱法(gas chromatography-mass spectrometry, GC-MS)分析,结合NIST 08标准谱库数据,比较普通番荔枝与刺果番荔枝挥发性香气成分组成差异。结果实验中共检出70种挥发性香气物质,其中酯类25种、醇类18种、烯烃类12种、酮类8种、醛类6种,酸类与烷烃类各1种,普通番荔枝占57种,刺果番荔枝占33种。2者拥有20种相同的挥发性香气成分,分别为乙醛、乙醇、丙醇、正丁醛、乙酸乙酯、异丁醇、正丁醇、丁酸甲酯、异戊醇、顺-3-己烯醇、正己醇、2-庚醇、丁二酮、柠檬烯、正辛醇、2-壬酮、芳樟醇、苯乙醇、辛酸甲酯、辛酸乙酯。此外,普通番荔枝特有37种挥发性香气成分,而刺果番荔枝有13种。结论 2种番荔枝共有的挥发性香气成分构成番荔枝属果实的基本香气,成分间含量的差异使得番荔枝之间大体香气相似但亦有轻微差异,各自拥有特有挥发性香气组成则构成它们自身的特征香。     

Olfactory and quantitative analysis of volatiles in elderberry (Sambucus nigra L) juice processed from seven cultivars

Aroma compounds emitted from elderberry juices processed from seven cultivars were collected by the dynamic headspace technique and analysed by GC–FID and GC–MS. Forty aroma compounds were identified and quantified, including nine compounds which had not previously been detected in elderberry juice. Significant differences were found among cultivars in the concentration levels of 30 compounds. The sensory characteristics of the individual aroma compounds in elderberry juice were determined by a GC‐sniffing technique, and the compounds were grouped according to their odour. The characteristic elderberry odour is due to dihydroedulan and β‐damascenone, of which the former occurs in relatively high concentrations in the headspace of elderberry juice. The fruity group consisted of aliphatic alcohols and aldehydes and aromatic esters, of which 1‐pentanal, 2‐methyl‐1‐propanol, 2‐ and 3‐methyl‐1‐butanol, 1‐octanal, 1‐octanol and methyl and ethyl benzoate contributed with fruity notes. In the flowery group, 1‐nonanal, nerol oxide and (Z)‐ and (E)‐rose oxide contributed with characteristic elder flower odour, whereas other flowery notes were associated with hotrienol, linalool and α‐terpineol. Fresh and grassy odours were correlated with 1‐hexanal, (E)‐2‐hexen‐1‐al, (Z)‐3‐hexen‐1‐ol, (E)‐2‐hexen‐1‐ol and (E)‐2‐octen‐1‐al of the grassy group, whereas 1‐octen‐3‐ol and 1‐octen‐3‐one of the agrestic group contributed significantly with the characteristic aroma of mushrooms. © 2000 Society of Chemical Industry     

Studies on Starch Isolated from the Fruits of Annona reticulata (Ramphal)

Pulp of Annona reticulata fruits yields about 19% starch. Purification of the crude products was achieved by treatment with sodium hydroxide to remove the other ingredients. The presence of starch was confirmed by treatment with amylolytic enzymes. Microscopic techniques were used to characterize the granular characteristics of the starch. Viscosity data of the purified starch indicate that the starch isolated from the pulp has paste characteristics comparable with those of corn starch. Results of the acid and enzymic hydrolysis of the fibrous material suggest the cellulosic nature of the residual material.     

Aroma volatiles recovered in the water phase of cashew apple (Anacardium occidentale L.) juice during concentration

BACKGROUND: There is a considerable loss of volatile compounds during the thermal concentration of cashew apple juice, damaging product quality, and as yet there is little research on the subject. Thus the purpose of this research was to identify the aroma volatiles evaporated off from cashew apple juice and recovered in the water phase during concentration of this beverage in an industrial plant. Water phase volatiles were extracted using dichloromethane, concentrated under a nitrogen flow, separated by gas chromatography (GC) and identified by GC‐mass spectrometry. In order to determine the contribution of each volatile to the cashew aroma, five trained judges evaluated the GC effluents using the Osme GC‐olfactometry technique. RESULTS: 71 volatiles were identified; of these, 47 were odour active. Alcohols were preferentially recovered in the cashew water phase, notably heptanol, trans ‐3‐hexen‐1‐ol and 3‐methyl‐1‐butanol, representing 42% of the total chromatogram area and imparting green grass and fruity aroma notes to the water phase. Esters represented 21% of the total chromatogram area, especially ethyl 2‐hydroxyhexanoate, ethyl trans ‐2‐butenoate and ethyl 2‐methylbutanoate, and were responsible for the fruity/cashew‐like aroma of the water phase. On the other hand, 3‐methylbutanoic and 2‐methylbutanoic acids were the volatiles that presented the greatest odour impact in the GC effluents of the water phase. CONCLUSION: Overall, the results of the present study strongly indicated that further concentration of the esters recovered in the water phase, either by partial distillation or by alternative technologies such as pervaporation, could generate a higher‐quality natural cashew apple essence. Copyright © 2011 Society of Chemical Industry     

Studies on frozen pourable custard apple (Annona squamosa L) pulp using cryoprotectants

Custard apple pulp treated with 100 ppm ascorbic acid as antibrowning agent and packed in 200 gauge polyethylene was frozen at −25 °C in an alcohol bath and stored at −18 °C in a deep‐freeze. The effect of three cryoprotectants (w/w), namely 0.5% propylene glycol (I), 0.5% glycerol (II) and 2% glycerol + 1% propylene glycol + 10% glucose syrup + 10% maltodextrin (III), on the thawing time of this pulp was studied for a period of 3 months. A control sample without any cryoprotectant was included for comparison. The half‐life for ascorbic acid degradation was monitored in the control pulp and that containing the cryoprotectants. It was found that formulation (III) gave a product that was pourable even on frozen storage and also had the highest half‐life of 75.33 days for ascorbic acid degradation as compared to 34.82 days for the control. © 2000 Society of Chemical Industry     

果蔬汁(菠萝汁)蒸发浓缩过程中营养损失动力学

为研究异形竖板降膜蒸发器浓缩蔬菜汁时蒸发温度对品质的影响,对蒸发浓缩过程中营养损失动力学进行分析研究,结合Arrhenius模型、Z值模型、H-E模型,建立蒸发浓缩果蔬汁时营养损失的新的动力学模型;同时给出反应级数的精确计算方法。     

Some properties of yoghurt produced by adding mulberry pekmez (concentrated juice)

Fruit-flavoured yoghurt was made by adding 2.5, 5.0, 7.5 and 10.0% mulberry pekmez (MP) into milk. The effects of the MP on the quality and fermentation process of the yoghurt were determined. The titratable acidity, pH, viscosity, whey separation and lactic acid bacteria (LAB) counts were determined at weekly intervals for 28 days. The pH range of the MP yoghurts was 4.65–5.57 and the pH of the plain yoghurt was 4.47 ( P  < 0.05). The addition of MP led to an increase in the fermentation time and a decrease in the viscosity of the yoghurts. Statistically significant differences were found between the plain and MP yoghurts in terms of pH (4.01 and 4.35), viscosity (5429 and 3175 cP) and number of LAB (7.07 and 6.48 log cfu). During storage, the titratable acidity, viscosity and LAB counts of MP yoghurts were lower and the whey separations higher than those of controls.     

Determination of vitamin K in aojiru (green juice) products by HPLC

A survey of vitamin K contents was carried out on 41 aojiru products and 10 vegetable juice products that were purchased from local markets. Aojiru is a health food made from green vegetables such as kale, ashitaba, mulberry leaf, barley grass and the like. The products are usually provided in various forms, such as frozen, powder and tablet. Vitamin K in samples was extracted with n-hexane, and separated on a C18 column with methanol-ethanol (95 : 5). After separation, vitamin K was converted to the hydroquinone form on a reduction column and determined with a fluorescence detector at lambdaex 240 nm and lambdaem 430 nm. The contents of vitamin K1 (phylloquinone) in frozen samples (n = 8), powder samples (n = 26) and tablet samples (n=7) were 90-190, 410-3,300, and 640-3,100 microg/100 g, respectively, and that in vegetable juice (n= 10) was 1-12 microg/100 g. Vitamin K2 (menaquinone) was not detected. The daily intake of vitamin K from aojiru products was estimated to be 99-380, 20-250 and 27-210 microg/day for frozen, powder and tablet types, respectively. These results suggest that patients prescribed warfarin should take care about their intake of vitamin K from aojiru products.     

The volatiles of off-flavoured unblanched green peas (Pisum sativum)

Volatile extracts of moderately off-flavoured frozen peas, prepared by vacuum sublimation followed by concentration of the sublimate by low temperature vacuum distillation, were examined by gas chromatography, silica gel chromatography and combined gas chromatography–mass spectrometry. The constituents identified included alcohols (29), carbonyls (31), esters (12), hydrocarbons (19), terpenes (6) and 3-alkyl-2-methoxypyrazines (3). Olfactory monitoring of the gas chromatographic column effluent indicated that most of the strong odours were associated with alkanals, alk-2-enals, alka-2,4- and 2,6-dienals, octa-3,5-dien-2-ones, 3-alkyl-2-methoxypyrazines and hexanol. However, no compound which, by itself, could account for the “hay-like” off-flavour of peas was evident. The off-flavour is considered to be complex and composed largely of the more odorous unsaturated carbonyls derived from the enzymic breakdown of the unsaturated pea lipids. The volatiles of pea shells similarly examined were found to contain many of the compounds present in peas.