Identification of aroma-active compounds in ‘wonderful’ pomegranate fruit using solvent-assisted flavour evaporation and headspace solid-phase micro-extraction methods

During the last few years, there has been a tremendous increase in consumption of pomegranate fruit and juice. Nevertheless, very little is yet known regarding the volatile constituents that determine the unique aroma of pomegranate fruit. We extracted aroma volatiles from fresh ‘Wonderful’ pomegranate juice using solvent-assisted flavour evaporation (SAFE) and headspace solid-phase micro-extraction (HS-SPME) methods, and applied gas chromatography–olfactometry (GC–O) (‘sniffing’) combined with gas chromatography–mass spectrometry (GC–MS) analysis, in order to identify volatile aroma-active compounds. In addition, we performed stir bar sorptive extraction (SBSE) of pomegranate aroma volatiles, coupled with GC–MS analysis, in order to assist in identifying aroma-active compounds. Overall, we tentatively identified 23 volatiles in the SAFE and HS-SPME extracts; they belonged to various chemical classes, including aldehydes, terpenes, alcohols, esters, furans and acids. Using the GC–O nasal impact frequency method, we tentatively detected 12 aroma-active peaks and identified the corresponding odourants by GC–MS. The aroma-active compounds of ‘Wonderful’ pomegranates were ethyl-2-methylbutanoate (fruity, apple), hexanal (green), β-pinene (pine, herbal), β-myrecene (woody, musty), cis-3-hexenal (green), limonene (fruity, musty), cis-2-heptenal (soapy, mushroom), cis-3-hexenol (earthy, grassy), 2-ethylhexanol (floral), β-caryophyllene (fruity, musty), 2(5H)-furanone (sweet, fruity) and β-sesquiphellandrene (terpene, almond). Overall, the flavour of ‘Wonderful’ pomegranate fruit derives from a mixture of various ‘green’, ‘woody’, ‘earthy’, ‘fruity’, ‘floral’, ‘sweet’ and ‘musty’ notes.     

Effects of fruit bagging on anthocyanins, sugars, organic acids, and color properties of ‘Granny Smith’ and ‘Golden Delicious’ during fruit maturation

The effects of fruit bagging on anthocyanins, sugars, organic acids, and color properties of ‘Granny Smith’ and ‘Golden Delicious’ were investigated in this study. Young fruits were bagged 40 days after flowering (DAF) with paper bags. The bagged fruits of ‘Golden Delicious’ were uncovered and exposed to light 120 DAF, while those of ‘Granny Smith’ 160 DAF. The fruits were harvested after 0, 2, 4, 6, 8, 10, and 15 day of bag removal, respectively. The development of anthocyanins, sugars, organic acids, and color properties in the flesh of ‘Granny Smith’ and ‘Golden Delicious’ was determined. After bag removal, the ‘Granny Smith’ and ‘Golden Delicious’ turn red, a* was consequently augmented, while L*, b*, C*, and h⁰ reduced. Cyanidin 3-galactoside and cyaniding 3-arabinoside were identified in ‘Granny Smith’ and ‘Golden Delicious’ as the two constituents responsible for red color of apple peel, and with cyanidin 3-galactoside being the most abundant anthocyanin in these non-red cultivars. Fructose, sucrose, and sorbitol were the major sugars and sugar alcohol, and malic acid was the major organic acid. Concentrations of most sugars and all organic acids quickly increased during 0–4 DABR, suggesting that synthesis of these sugars and organic acids was inhibited by fruit bagging. Furthermore, the cy3-gal and cy3-ara accumulation of all tested cultivars was significantly correlated with sucrose, indicating that sucrose may be the more important factors in the biosynthesis of anthocyanin.     

Field study on the microbiological quality of pickles in brine and survival of Salmonella Typhimurium and Listeria monocytogenes during storage at 4 °C

The aim of this study was to assess the microbiological quality and the ability of Listeria monocytogenes and Salmonella enterica serovar Typhimurium strains to survive during storage at 4 °C of all available brand names of brined pickles and some in-bulk ones, in the district of Athens. None of the samples could be characterized as heavily contaminated. The microbial populations detected could be due to inadequacy of packaging, regarding the ones available in-bulk and improper thermal treatment in the case of the canned ones. Moreover, the ability of both pathogens to survive for 5 days at 4 °C, in some products, has been exhibited.     

Polyphenol oxidase,total phenolics and ascorbic acid changes during storage of minimally processed ‘California Wonder’ and ‘Quadrato d'Asti’ sweet peppers

A growing sector of ‘minimally processed’ vegetables market is represented by sweet peppers, whose quality may be affected by enzymatic activities. Among these, polyphenol oxidase leads to browning reactions, which is a major cause of quality loss. This research aimed at assessing the changes in PPO activity, total phenolics and ascorbic acid throughout a 30-days cold storage in minimally processed green (cv. ‘California Wonder’), yellow and red (cv. ‘Quadrato d'Asti’) sweet peppers. At day 0 PPO was active in red and yellow fruits but not in green ones, where it started to show relevant activity from the 3rd week of storage. At the end of the storage period (day 30), PPO activity was 1.36, 0.94 and 0.61 U/g d.m. in yellow, red and green peppers, respectively. Total phenols content was highest in green peppers, followed by red and yellow ones. In green fruits it increased up to the 3rd week of storage, decreasing afterwards, whilst in red and yellow fruits phenols content progressively declined after the 2nd week. Yellow fruits showed the highest ascorbic acid content, followed by red and green ones.Results confirm that green peppers ‘California Wonder’ are more suitable to minimal processing than yellow and red fruits.     

Changes in quality attributes of pulsed light and thermally treated mixed fruit beverages during refrigerated storage (4 °C) condition

The effect of batch pulsed light (PL) irradiation (3000 J cm⁻²) on the shelf-life of the beverage blend comprising apple ber (Indian jujube), carambola (star fruit), and black table grapes was investigated. The equivalent thermally treated beverage (90 °C|5 min) exhibited greater stability from microbial and enzymatic spoilage but retained 27% less antioxidants and 14% less vitamin C than PL-treated juice. Thermally and PL-treated blends possessed sensory scores of 5.8 and 7.2, respectively. The beverage's microbial shelf-life (population ≤ 6-log₁₀ cfu/mL) was extended to 45 days at 4 °C after the PL treatment. The PL exposure did not alter the pH and soluble solids during storage. The PL-treated juice, after 45 days, was placed on par with the freshly prepared juice by the sensory panel. The PL-treated juice preserved 61% more antioxidants, 38.8% more phenolics, and 68.2% more vitamin C than the thermally pasteurized beverage after 45 days of refrigerated storage.Industrial relevanceWhile the fruit processing industry demands microbial safety and enzymatic stability, today's consumer demands juices of high nutritional quality. This study utilizes under-explored fruits like apple ber (Indian jujube) and carambola (star fruit) to make a shelf-stable mixed fruit beverage. This study will help the industry understand the potential of PL treatment in accomplishing microbial safety, enzymatic stability, and nutritional quality, along with the utilization of under-explored fruits.     

Changes in cuticle compositions and crystal structure of ‘Bingtang’ sweet orange fruits (Citrus sinensis) during storage

Changes in composition and structure of orange cuticle during storage at 4°C or 25°C for 40 days were investigated. The total epicuticular wax content of fruits increased during storage at 4°C for 30 days and then decreased as storage time prolonged to 40 days, while it increased continuously at 25°C for 40 days. The total intracuticular wax content of fruits increased to 9.70 μg cm^?2 stored at 4°C for 10 days and then decreased to 6.74 μg cm^?2 for 40 days. The total intracuticular wax content of fruits was decreased to 5.17 μg cm^?2 stored at 25°C for 10 days and then increased to 10.06 μg cm^?2 for 30 days. Fatty acids were the most abundant component of the epicuticular wax and terpenoids were restricted to the intracuticular wax. Terpenoids were restricted to the intracuticular wax, and their amounts in the fruit stored at 4°C increased continuously during the first 20 days of storage at 4°C and then decreased as storage time increased up to 40 days. Although significant changes were found in the contents of the cutin monomer, their proportions did not change significantly during storage at 4°C or 25°C. Size of wax platelets crystals wax increased during storage of fruits at 4°C up to 30 days; however, the crystals were degraded and decreased as storage prolonged to 40 days. Furthermore, the shape of the fruit cuticle surface wax crystals changed from flattened platelets to small granulelike after storage at 25°C for 20–40 days. The obtained results provide detailed information about the changes in orange cuticle occur during storage at varying temperatures, which may help in preserving the quality of citrus fruits during storage.     

Effect of Eryngium caeruleum essential oil on microbial and sensory quality of minced fish and fate of Listeria monocytogenes during the storage at 4°C

The present study investigated in vitro antimicrobial activity of Eryngium caeruleum essential oil (EEO) against five foodborne pathogenic bacteria based on microdilution and disk diffusion methods. Moreover, its effects on specific spoilage microorganisms, inoculated Listeria monocytogenes, and its sensory changes in minced fish were evaluated during 12 days of storage at refrigeration temperature. The results showed that Staphylococcus aureus and Escherichia coli were the most sensitive and the most resistant bacteria with a minimum inhibitory concentration of 0.125 and 1 mg/ml, as well as inhibition zones of 15.66 and 11.66 mm, respectively. Regarding the antimicrobial effect of EEO on the microbial profile and inoculated L. monocytogenes, treating with 0.4% EEO caused a significant decrease in the studied microorganisms when compared to the control group (p < 0.05). In addition, considering the sensory evaluation, the best scores were observed for the samples treated with 0.2% and 0.4% EEO. However, none of the groups obtained acceptable scores until the final day of storage except for the color attribute. In general, sensory evaluation and its correlation with microbial counting indicated that the treatment with 0.4% EEO was able to preserve the microbial quality of the minced fish at refrigeration temperature without any undesirable sensory effects.     

Impacts of crop level,soil and irrigation management in grape berries of cv ‘Trincadeira’ (Vitis vinifera L.)

Berry size and crop yield are widely recognized as important factors that contribute to wine quality. The final berry size indirectly affects the phenolic concentration of the wine due to skin surface-to-berry volume ratio. The effects of different irrigation levels, soil management and plant crop level on growth of ‘Trincadeira’ berries were studied. In order to test the influence of different irrigation levels (rainfed, pre-veraison and post-veraison), different soil management (tillage and natural cover crops) and different plant crop levels (8 and 16 clusters per vine), leaf water potential, skin anthocyanin, polyphenols, berry skin and seed fresh weight were measured in fruits. The segregation of berries into three different berry classes: small, medium and large, allowed to identify different levels of contribution of soil management and irrigation level into berry, skin and seeds ratios. As expected, higher water availability due to irrigation and soil tillage management during berry development induced an increase in berry flesh weight and this was more evident in larger berries; however, berry skin and seed fresh weight remained unchanged. Also, anthocyanins did not show significant differences.