Effect of UV-C Irradiation on the Shelf Life of Fresh-Cut Potato and Its Sensory Properties after Cooking.

Research background: Potato tissue is damaged during fresh-cut production, which makes fresh-cut potato susceptible to the quality loss and microbiological spoilage. At the same time, such products are desirable due to their convenience; however, they are extremely sensitive and have short shelf life. The main challenge of the fresh-cut potato industry is to find possibilities to overcome these drawbacks. UV-C treatment, known for its antibacterial activity, is a promising technique and it shows a potential to improve shelf life of fresh-cut potato products. Experimental approach: The influence of the UV-C treatment on the safety and quality, as well as sensory traits of fresh-cut potato (Solanum tuberosum L. cv. Birgit) during storage was examined. For this purpose, 0-, 3-, 5- and 10-min UV-C irradiation was applied on vacuum-packed potato slices pretreated with sodium ascorbate solution. During 23 days of storage at (6±1) °C, microbiological, physicochemical and sensory properties of raw samples were monitored, along with sensory properties of boiled and fried fresh-cut potatoes. Results and conclusions: The 5- and 10-min UV-C treatments significantly reduced microbial growth, increased total solids and lightness (L*), and positively affected odour and firmness of raw potatoes. Cooked UV-C-treated samples were described with more pronounced characteristic potato odour and taste. Overall, UV-C-treated fresh-cut potato retained its good quality and sensory traits up to 15 days at (6±1) °C. Novelty and scientific contribution: To the best of our knowledge, this is the first scientific article dealing with the effect of UV-C light on durability (safety, quality and sensory traits) of fresh-cut potato cv. Birgit and its suitability for boiling and frying. In general, UV-C treatment is a known antimicrobial technique, but its application on fresh-cut potato is poorly explored. Results confirmed that vacuum-packed fresh-cut potato treated only with UV-C and sodium ascorbate as anti-browning agent, without the addition of chemical preservatives, had twofold longer shelf-life at (6±1) °C than the fresh-cut potato not treated with UV-C. Fresh-cut potato treated with UV-C retained good overall quality and sensory properties either raw, boiled or fried. Results of this study could also be useful for producers in terms of potential UV-C application as a strategy for prolonging the shelf-life of fresh-cut potato.

Physical, Chemical and Sensory Characterization of Deep-Fried Fresh-Cut Potatoes Coated with Hydrocolloid/Herbal Extracts.

Research background: Recently, natural plant extracts have been used to increase the nutritional value of food and to potentially reduce the absorbed fat and the formation of acrylamide in fried foods. Literature data on the use of edible polymers with nettle or olive leaf extracts are scarce. Experimental approach: The effect of novel coatings on colour, fat absorption, phenolic and sugar content, and acrylamide formation in deep-fat-fried fresh-cut potatoes was evaluated. Extracts of olive and nettle leaves were incorporated in carboxymethyl cellulose (CMC) and gum arabic, used as coatings for potatoes and applied before frying. This aimed to improve the nutritional quality of deep-fat-fried fresh-cut potatoes. Results and conclusions: Enrichment of the edible coatings with extracts resulted in a significant change in the visible colour of the potatoes before frying. Significant effect of the extract amount on the sensory characteristics of potatoes was also observed. Most importantly, the perception of characteristic potato odour and taste was not significantly affected by the coating. Although higher amounts of the extract (1.5%) resulted in higher phenolic mass fraction in fried potatoes, the sensory scores decreased. After frying, fat mass fraction in the coated potatoes was reduced by about 15% compared to the uncoated samples. The type of extract affected the total sugar mass fraction in fried potatoes, which was lower in the samples with coatings enriched with olive leaf than in those with nettle leaf. Only gum arabic coating had a reducing effect on acrylamide mass fraction by 17%. Based on all the obtained results, CMC and gum arabic coatings did not influence sensory properties, so they can be recommended as carriers of functional compounds or as a frying pre-treatment for potatoes with favourable effect on fat and acrylamide content. Novelty and scientific contribution: The knowledge obtained in this study can be exploited for preparation of coatings with functional compounds used as a pre-treatment for fried food with favourable effect on fat and acrylamide content.

Effect of UV-C Irradiation, Storage and Subsequent Cooking on Chemical Constituents of Fresh-Cut Potatoes.

UV-C irradiation successfully reduces the growth of microorganisms, but it can also affect the content of phenolics and sugars of fresh-cut potatoes (FCP). This could consequently alter antioxidant capacity of FCP or its potential for acrylamide formation. Therefore, this paper investigates the influence of UV-C irradiation on the content of phenolics [chlorogenic acid (CA)] and individual sugars during storage of FCP as well as after cooking. Acrylamide was also monitored in FCP after frying. Potato slices pre-treated with sodium ascorbate solution and vacuum-packaged were UV-C irradiated for 0, 3, 5, and 10 min in order to obtain irradiation doses of 0, 1.62, 2.70, and 5.40 kJ m-2, respectively, stored for 23 days (+6 °C), and subsequently boiled and fried. As the applied dose and storage duration increased, the CA content in raw FCP decreased (it retained for 75.53-88.34%), while the content of sugars as well as acrylamide in fried FCP increased. Although the increase was the most noticeable at the applied dose of 2.70 kJ m-2, the acrylamide content was always below proposed limit. Boiling and frying reduced the content of CA and sugars. In spite of certain alterations, applied doses of irradiation can ensure acceptable product in regard to phenolics and sugars, and acrylamide content particularly.

Chemical constituents of fresh-cut potato as affected by cultivar, age, storage, and cooking.

Certain changes in phenolics and sugars can occur during the storage of potatoes, where particularly amounts of sugars represent the critical factor as they are involved in potentially harmful acrylamide (AA) formation during frying. This research investigates the impact of cultivars (Birgit and Lady Claire), tuber's age (1, 5, and 9 months), and storage duration (1, 5, and 8 days at 10 °C) on the content of phenolics and sugars in raw, boiled, and fried fresh-cut potato (FCP). The influence of these factors on the formation of AA in fried FCP was also assessed. Significant differences in phenolics and sugars were observed between cultivars (cv. Birgit contained 5.77 mg of phenolics 100 g-1 of dry weight (DW) and 1.75 g of sugars 100 g-1 DW, while cv. Lady Claire contained 10.13 mg of phenolics 100 g-1 DW and 0.65 g of sugars 100 g-1 DW). The content of phenolics significantly decreased, while sugars increased during tubers' aging. FCP storage time had no significant influence on the content of phenolics and sugars. The phenolics and sugars were the highest in the raw samples and the lowest in the boiled ones. Although the AA level in fried samples was significantly influenced by cultivar (Birgit > Lady Claire) and it increased with FCP storage time, it was below European Food Safety Authority (EFSA) regulation's approved maximum value (750 µg kg-1 FW) in both cultivars. Therefore, cvs. Birgit and Lady Claire could be considered as promising FCP cultivars and for frying purposes. PRACTICAL APPLICATION: The results of this research reveal that quantitative changes of chemical constituents occurring during storage and cooking of fresh-cut slices of potato cultivars Birgit and Lady Claire are not a concern. This is of particular importance to fresh-cut producers and customers. Phenolics were reduced during storage, but they were still present in all cooked samples independently of the cooking method. The analysis of sugars showed that tubers as old as 9 months could be used for fresh-cut potato processing, providing safe frying without critical levels of acrylamide.

Fresh-cut potato quality and sensory: Effect of cultivar, age, processing, and cooking during storage.

This work examined the influence of cultivar, tubers' age, antibrowning agent, package atmosphere, and storage time on fresh-cut potatoes' (FCPs) physical, chemical, and sensory properties. Potato slices of cv. Birgit and Lady Claire tubers sampled during the first, fifth, and ninth months of storage were dipped in solutions of (1) sodium chloride (1%) and (2) sodium ascorbate (2%), and stored for 8 days in (1) vacuum and (2) active modified atmosphere (MAP) (10.0% CO2 , 3.0% O2 , and 87.0% N2 ) at 10 °C. During storage, O2 and CO2 content (%) within packages was measured and samples were analyzed for weight loss, total solids (TS) and soluble solids (SS), pH, color, texture, and sensory properties of raw, boiled, fried, and baked FCP. Results showed that 9 months' aging had a significant impact on almost all investigated FCP properties, but differences among first, fifth, and ninth months were numerically feeble for some parameters in raw samples: TS changed from 22.14% to 20.98%, SS 5.53% to 6.93%, pH 6.02 to 5.98, L* 70.10 to 68.87, C* 35.75 to 36.70, H° 89.29 to 88.15, and firmness 7.25 to 8.13N. Furthermore, 9 months of aging had no significant influence on the characteristic odor of raw, boiled, fried, and baked FCP and characteristic taste of fried and baked FCP, whereas boiled FCP characteristic taste remained unchanged for 5 months of aging. Fried FCP was better sensory evaluated than baked ones, cv. Birgit was more suitable for the FCP production compared to cv. Lady Claire as well as vacuum packaging and sodium ascorbate better preserved samples quality and sensory than sodium chloride and MAP. PRACTICAL APPLICATION: This study could be helpful to fresh-cut potato (FCP) producers because results indicate that for FCP processing, along with the selection of cultivar, antibrowning agent, and packaging type, tubers' age also requires attention. A further contribution of this research is related to the adequate way of FCP cooking, where frying shows the best results according to the quality and sensory assessment.

Quality and Sensory Study of Fresh Sour Cherry Juices Upon Cultivar, Growing Area and Weather Conditions.

Freshly squeezed sour cherry (Prunus cerasus L.) juices of Maraska Brac (BR), Maraska MA (MA), Oblacinska 18 (18), Oblacinska Osjecka (OS), Rexelle (REX), Heimann conserved (HEI), and Kelleris 16 (KEL) grown in different climate regions (Mediterranean and continental) in two consecutive harvest years were analyzed for quality and sensory properties. Obtained results showed that investigated sources of variation (cultivar, growing area, harvest year) significantly influenced physical, chemical, and sensory properties of tested juices. All juices had high soluble solids (SS) (17.26% to 25.89%), especially BR (24.19%), MA (25.89%), 18 (24.66%), and OS (23.61%). Juices also had considerable total phenols (TP) content (2.19 to 5.87 mg GAE ml-1 ) and antioxidant capacity (AC) (0.020 to 0.045 mmol TE mL-1 ) with BR, MA, REX, and HEI containing the highest amounts of bioactive compounds (BR = 5.87 mg GAE mL-1 , MA = 5.68 mg GAE mL-1 , REX = 4.42 mg GAE mL-1 , HEI = 4.27 mg GAE mL-1 ). Sensory evaluation showed that all juices had satisfying sensory profiles with BR, MA, 18, OS, and KEL juices scoring particularly high (5.3 to 8.9 of 10) in desirable sensory properties (color intensity [CI], sour cherry taste [SCT], harmonious taste [HT], taste fullness [TF], sour cherry odor [SCO], and viscosity [V]) of fresh sour cherry cloudy juice. Juices from Mediterranean area achieved higher values for SS, pH, SS/TA ratio, TP, AC, SCT, HT, TF, SCO, and V compared to continental zone juices. Harvest year with higher temperatures and less rainfall also resulted in higher SS, pH, TP, and AC as well as stronger expression of desirable sensory properties. PRACTICAL APPLICATION: The results of this study provide an insight into sour cherry potential for use in functional food products, including today's popular smoothies, since it is fruit rich with health contributing compounds and possesses desirable sensory characteristics (color intensity, sour cherry taste, harmonious taste, taste fullness, sour cherry odor, and viscosity) at the same time, which can differ due to cultivar, climate diversity as well as weather conditions.

Influences of organically and conventionally grown strawberry cultivars on anthocyanins content and color in purees and low-sugar jams.

The objective of this study was to detect influences of cultivar, cultivation and processing on anthocyanin content and color in purees and low-sugar jams produced from strawberry cultivars (Elsanta, Maya, Marmolada, Queen Elisa), grown under conventional and organic cultivation. Color was determined by CIELab values while anthocyanins were quantified by HPLC-UV/VIS-PDA. Queen Elisa was the best cultivar for processing as it had highest total anthocyanin content (TAC) that was well preserved in processing. On average, processing purees to jams decreased TAC for 28% where pelargonidin-3-glucoside revealed most noticeable loss (53%) and cyanidin-3-rutinoside was best preserved in processing. Obtained results indicated that measurement of colorimetric parameters are strongly correlated with content of anthocyanins. In other words, loss of anthocyanins during processing was accompanied by noticeable decrease in lightness, red/yellow color and total color change. Results showed that change of color is useful predictor for estimating anthocyanins in strawberry purees and jams.

Influence of Cultivar and Industrial Processing on Polyphenols in Concentrated Sour Cherry (Prunus cerasus L.) Juice.

The objective of this study is to investigate the influence of cultivar and industrial processing on total polyphenols, anthocyanins, hydroxycinnamic acids and antioxidant activity in concentrated sour cherry (Prunus cerasus L., cvs. Marasca and Oblacinska) juices. Samples were collected during four processing steps: from fresh fruit prior to processing, then from pressed, filtered and concentrated juices. The content of total phenols was the same in both cultivars, but antioxidant activity (Oblacinska>Marasca) and total monomeric anthocyanins (Marasca>Oblacinska) differed. All processing steps significantly influenced the content of total phenols, total monomeric anthocyanins and antioxidant activity. In all samples four major anthocyanins were identified by HPLC with UV/VIS PDA detector, listed in the descending order based on their abundance: cyanidin-3-glucosylrutinoside, cyanidin-3-rutinoside, cyanidin-3-sophoroside and cyanidin-3-glucoside. Marasca cv. contained more total anthocyanins, and contents of cyanidin-3-sophoroside and cyanidin-3- -glucosylrutinoside. The content of total hydroxycinnamic acids was also higher in Marasca than Oblacinska cv. After processing, the concentration of all identified anthocyanins increased in both cultivars. Majority of the highest values of polyphenols were detected in the juice after pressing. The content of polyphenols and their antioxidant activity were considerably stable during industrial processing to concentrated juice. Although Marasca had higher polyphenolic content than Oblacinska, both cultivars showed promising industrial potential for processing to concentrated juice.

Gel strength and sensory attributes of fig (Ficus carica) jams and preserves as influenced by ripeness.

In this article, gel strength and sensory attributes of jams and preserves made from figs at different stages of ripeness were investigated. Special emphasis was put on investigating the relationship of these attributes and pectin composition during ripening. Jams were produced with the addition of sugars and commercial pectin. In the production of preserves, no additional sugars or commercial pectin were used. Basic physicochemical properties (total solids, sugars, pH, total acidity) of figs were determined at all stages of ripeness. Total solids, sugars, and pH value increased in figs during ripening. To better understand the role of fig pectin in gel formation, the amount of 3 pectin fractions, soluble in water (PFW), soluble in oxalate (PFO), and soluble in alkali (PFA), as well as their gel-forming abilities were determined. The most abundant pectin fraction in figs was found to be PFO. Its amount was not influenced by the stage of ripeness. The amount of PFW and PFA decreased with increased ripeness of the fruit. Strength of gels formed with PFW and PFA isolated at different stages of ripeness followed the same trend. Gels made with PFO were remarkably softer in comparison with other gels. While strength of jams was not influenced by the ripeness of fig fruits, the strength of preserves decreased with increased ripeness of the fruit. The stage of ripeness did not have a significant influence on sensory attributes of jams or preserves. However, the type of product had a significant influence on taste, firmness, and color. Jams scored higher than preserves when these 3 attributes were evaluated.

Improved antioxidant and anti-inflammatory potential in mice consuming sour cherry juice (Prunus Cerasus cv. Maraska).

The present investigation tested the in vivo antioxidant efficacy (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase; Gpx), lipid peroxidation (LPO) and anti-inflammatory properties (cyclooxygenase-2; COX-2) of sour cherry juices obtained from an autochthonous cultivar (Prunus cerasus cv. Maraska) that is grown in coastal parts of Croatia. Antioxidant potential was tested in mouse tissue (blood, liver, and brain), LPO (liver, brain) and anti-inflammatory properties in glycogen elicited macrophages. Additionally, the concentration of cyanidin-3-glucoside, cyanidin-3-rutinoside, pelargonidin-3-glucoside, pelargonidin-3-rutinoside and total anthocyanins present in Prunus cerasus cv. Maraska cherry juice was determined. Mice were randomly divided into a control group (fed with commercial food pellets) and 2 experimental groups (fed with commercial food pellets with 10% or 50% of cherry juice added). Among the anthocyanins, the cyanidin-3-glucoside was present in the highest concentration. These results show antioxidant action of cherry juice through increased SOD (liver, blood) and Gpx (liver) activity and decreased LPO concentration. The study highlights cherry juice as a potent COX-2 inhibitor and antioxidant in the liver and blood of mice, but not in the brain. Thus, according to our study, Prunus cerasus cv. Maraska cherry juice might potentially be used as an antioxidant and anti-inflammatory product with beneficial health-promoting properties.

Phenolic profiles of raw apricots, pumpkins, and their purees in the evaluation of apricot nectar and jam authenticity.

The possibility of proving the undeclared addition of pumpkin puree in apricot nectars and jams has been investigated by using the phenol compound fingerprint and sensory evaluation. The cheaper pumpkin admixtures in apricot nectars and jams could not be detected by the sensory evaluation, particularly if present in quantities of <15%. The lower admixtures of pumpkin puree in apricot nectars and jams could be detected by the presence of syringic acid, a phenolic compound characteristic of the investigated pumpkins (Cucurbita pepo cv. Gleisdorff and Table Gold, Cucurbita maxima cv. Turkinja, and Cucurbita moschata cv. Argenta). Syringic acid was isolated from pumpkin puree and determined by using HPLC with diode array detection. By using the phenolic profile, undeclared pumpkin admixture (> or =5%) in the apricot nectars and jams could be proven.