Pablo Melgarejo

Volatile composition and sensory quality of Spanish pomegranates (Punica granatum L.)

BACKGROUND Pomegranate is highly valued for its health-promoting effects. Fruits of nine pomegranate cultivars were analysed for volatile compounds, antioxidant activity and quality parameters, including maturity index and CIEL*a*b* colour. Volatile compounds were isolated from fresh juices using hydrodistillation; extracts were analysed using gas chromatography/mass spectrometry. Fruit colour was influenced by cultivar and grouping of cultivars according to their taste (sweet, sour-sweet or sour), with sweet fruits having more intense red colour and higher lightness values. RESULTS A total of 18 compounds were found in pomegranate aroma profiles, including monoterpenes, aldehydes, alcohols, monoterpenoids and linear hydrocarbons. The most abundant compound were trans-2-hexenal, 3-carene, α-terpinene and α-terpineol. The total concentration of volatiles ranged from 1.7 to 10.9 g kg(-1) . Overall consumer liking of pomegranate juices was associated with the presence of monoterpenes such as α-pinene, β-pinene, β-myrcene, limonene and γ-terpinene. The presence of aldehydes such as hexanol, hexanal and cis-3-hexenol was correlated with poor overall consumer liking. CONCLUSION Fruits from the cultivar Mollar de Elche 2 were those most suited for juice processing because they had the highest total concentration of volatiles, which was related to high overall consumer liking, intense and acceptable fresh pomegranate odour and flavour (high scores of satisfaction degree), medium intensity of red colour and low sourness.

Volatile Composition of Pomegranates from 9 Spanish Cultivars Using Headspace Solid Phase Microextraction

Fruits of 9 Spanish pomegranate cultivars were analyzed for quality parameters, volatile composition, and sensory profile. Volatile compounds were extracted using headspace solid phase micro-extraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS) and flame ionization detector (GC-FID). Twenty-one compounds were found in the headspace of fresh pomegranate juices, including aldehydes, monoterpenes, and alcohols. The most abundant compounds were hexanal, limonene, trans-2-hexenal, and cis-3-hexenol. Fruits from the cultivars Mollar Elche(ME) ME14, ME1, and ME2 presented the highest values of overall liking by the consumer panel; however, their total volatiles concentration were low compared to the other pomegranate cultivars and their color intensity was intermediate. Overall consumer liking of pomegranate juices was mainly associated with the presence of monoterpenes (α-terpineol); however, high aldehydes (trans-2-hexenal) concentrations were correlated with poor overall consumer liking. Fruits from sour-sweet cultivars (PTO7 and ADO4) could improve the quality of ME pomegranate juices due to their intense color, high monoterpenes concentrations, and their moderate sourness. Practical Application: The information provided in this study proves that sour-sweet pomegranate fruits can be used in the manufacturing of pomegranate juices and will improve the sensory quality and the volatile composition of this product.

Potential of Spanish sour–sweet pomegranates (cultivar C25) for the juice industry

Commercial juices of sweet pomegranates and fresh juices of sour–sweet pomegranates were analysed for organic acids, sugars, antioxidant activity, volatile composition, sensory profile and consumer liking. Organic acids and sugars were analysed by high-performance liquid chromatography, while volatiles were extracted using hydrodistillation and analysed by gas chromatography–mass spectrometry and gas chromatography–flame ionisation detector. Malic acid was predominant in sweet juices while citric acid in sour–sweet samples. Fructose and glucose were found as the predominant sugars in all juices. A total of 18 compounds were found in pomegranate aroma profile, including monoterpenes, aldehydes, alcohols, monoterpenoids and linear hydrocarbons; the most abundant compounds were 3-carene, α-terpinene and α-terpineol. The total concentration of volatiles ranged from 2.0 up to 5.1 mg/L, with commercial samples presenting higher total concentrations due to the presence of peel volatiles. The high potential of sour-sweet pomegranate fruits for the juice industry was supported by (a) the high values of positive attributes, such as colour and fresh pomegranate flavour and (b) the high overall liking of consumers.

Organic Acids, Sugars, and Anthocyanins Contents in Juices of Tunisian Pomegranate Fruits

Juices made from fruits of 30 Tunisian accessions of pomegranate were studied for their organic acids, sugars, and anthocyanin contents, using high performance liquid chromatography. Among the detected organic acids, malic acid was the major one (>50%) followed by citric acid (>22%), while among sugars, fructose and glucose were most present in pomegranate juice contributing 53.9 and 43.4% of the total sugar content, respectively. The total anthocyanin content ranged from 9–115 mg per litre of juice with the following ranges of the six compounds found: cyanidin-3,5-diglucoside (3.1–74.4 mg/L), delphinidin-3-glucoside (0.7–22.0 mg/L), cyanidin-3-glucoside (0.8–21.0 mg/L), pelargonidin-3-glucoside (0.5–16.1 mg/L), pelargonidin-3,5-diglucoside (0.0–11.8 mg/L), and delphinidin-3,5-diglucoside (0.0–5.4 mg/L). Based on the analyzed parameters, cluster analysis allowed grouping cultivars into two main clusters. One was made of sour cultivars and the second of the sweet ones. Principle component and cluster analyses suggested that the composition of the pomegranate fruits is determined by cultivar rather than cultivation location.

Evaluation of Spanish Pomegranate Juices: Organic Acids, Sugars, and Anthocyanins

Six pomegranate (Punica granatum L.) cultivars belonging to the ‘Mollar’ group were evaluated under homogeneus growing conditions. Chemical parameters, such as sugars, organic acids, and anthocyanin contents, and other quality parameters, including fruit weight, pH, total soluble solids, titratable acidity, and colour, were evaluated. Fruit weight was not significantly affected by cultivar. The highest TSS content was detected in juice from MO6 (15.81 °Brix). All cultivars were sweet, and the ripening index ranged from 59.14 (ME5) to 87.95 (MO6). The composition of pomegranate juice was dependent on the cultivar. Glucose was the major sugar in all evaluated cultivars (60–64% of total sugars), followed by fructose, maltose, and sucrose. Among the detected organic acids, citric acid was the predominant (>54%). The total anthocyanin content ranged from 72 to 200 mg per litre of juice, being the main anthocyanin cyanidin 3-glucoside followed by cyanidin 3,5-diglucoside. The principal component analysis and cluster analysis showed high dissimilarity levels in cultivars ME5, MO6, MA4, and MA5.