Mirela Kopjar

Anthocyanins, Phenols, and Antioxidant Activity of Sour Cherry Puree Extracts and their Stability During Storage

In this study, influence of the types of solvent and extraction time on the anthocyanins, polyphenols, and flavonoids content, and antioxidant activity of the extracts from sour cherry puree was investigated. Water, methanol, and ethanol, as well as those acidified solvents (with hydrochloric and acetic acid) were used. Extraction time was 1, 3, or 24 h at room temperature. Stability of the obtained extracts was monitored trough 42 days of storage at room temperature and at 4°C. The most efficient extraction solvent for anthocyanin, phenol, and flavonoid was methanol acidified with hydrochloric acid. The highest content of investigated compounds was observed after one hour extraction, except in the case of phenols, where prolongation of extraction time enhanced extraction of above mentioned compounds. During storage of samples, anthocyanins, total phenols, flavonoids contents, and antioxidant activity decreased, while the percentage of polymeric color increased.

Prevention of thermal degradation of anthocyanins in blackberry juice with addition of different sugars Prevención de degradación termal de antocianinas en zumo de mora con adición de diferentes azúcares

The aim of this study was prevention of thermal degradation of blackberry juice anthocyanins through sugar addition. Blackberry juice samples were prepared without and with addition of 10% of different sugars (sucrose, fructose, glucose and trehalose), and heated at 50, 70 and 90 °C for 1 and 2 h. Since degradation of anthocyanins, over the time, followed first-order reaction model, calculation of the reaction rate constant (k), half-lives (t 1/2) and activation energy was conducted. During heating, at all investigated temperatures, degradation of anthocyanins occurred in higher or lesser extent. Addition of trehalose had the highest impact on anthocyanin stability during heating at all investigated temperatures and during both heating times. Samples with trehalose addition had the lowest k values thus the highest t 1/2 values at all investigated temperatures. In conclusion, careful formulation of foods, in our case sugar addition to blackberry juice, can minimise anthocyanins degradation during heating. El objetivo de este estudio fue la prevención de degradación termal de antocianinas de zumo de mora por la adición de azúcar. Se prepararon muestras de zumo de mora sin y con adición de 10% de diferentes azúcares (sacarosa, fructosa, glucosa y trehalosa) y se calentaron a 50, 70 y 90 °C durante 1 y 2 horas. Puesto que la degradación de antocianinas, durante el tiempo, siguió el modelo de reacción de primer orden, el cálculo de la constante de velocidad de reacción (k), semivida (t1/2) y energía de activación se llevó a cabo. Durante el calentamiento, en todas las temperaturas investigadas, la degradación de antocianinas sucedió en mayor o menor grado. La adición de trehalosa tuvo el mayor impacto en la estabilidad de antocianinas durante el calentamiento a todas las temperaturas investigadas y durante los dos tiempos de calentamiento. Las muestras con adición de trehalosa tuvieron unos valores k más bajos así como los mayors valores t1/2 a todas las temperaturas investigadas. En conclusión, la formulación cuidadosa de comidas, en nuestro caso adición de azúcar a zumo de mora, puede minimizar la degradación de antocianinas durante el calentamiento.

Influence Of Trehalose Addition On Instrumental Textural Properties Of Strawberry Pastes

Objective of this study was investigation of influence of trehalose addition (3, 5 and 10%) on instrumental textural properties of evaporated and freeze-dried strawberry pastes. As a control, strawberry paste without addition of trehalose was used. Addition of trehalose had influence on both, hardness and stickiness of the samples, but it is very important to define the amount of trehalose in order to achieve desirable properties. With addition of trehalose hardness of both, evaporated and freeze-dried samples decreased, from 29.89 N to 14.72 N for evaporated samples and from 184.83 N to 44.95 N in freeze-dried samples. Also, from those results it could be seen that freeze-dried samples were much harder than evaporated ones, regardless of trehalose addition. While hardness of samples decreased with addition of trehalose, stickiness increased. Stickiness values were from 0.016 N to 0.0102 N for evaporated samples, and from 0.066 N to 0.018 N for freeze-dried samples. Since evaporated samples had lower values for stickiness they were stickier than freeze-dried ones.

Volatile compounds of freeze-dried sour cherry puree affected by the addition of sugars

ABSTRACT The aim of this work was to determine the influence of the addition (5, 10, or 20 g/100 g) of different sugars (sucrose, maltose, or trehalose) prior to freeze-drying on the key volatile compounds of the sour cherry puree. The key volatile compounds of sour cherries were benzaldehyde, benzyl alcohol, and 2-hexenal. The results obtained for the samples with the addition of sugars were compared to the control sample, the sample without sugar addition. The control sample contained 3.92 mg/kg of benzyl alcohol, 856.61 µg/kg of benzaldehyde, and 15.58 µg/kg of 2-hexenal. Benzaldehyde, the compound described as the typical cherry volatile compound, was determined in the highest amount in the sample with the addition of 10 g/100 g of trehalose (937.51 µg/kg). The highest amount of 2-hexenal was determined in samples with the addition of 10 or 20 g/100 g of trehalose (17.45 and 18.96 µg/kg, respectively). All samples with the sugar addition had lower content of the benzyl alcohol than the control sample. Generally, samples with the addition of sucrose had the lowest amount of examined volatile compounds.

Modelling the Colour of Strawberry Spread During Storage, Including Effects of Technical Variations

Abstract The colour of freshly processed strawberry spread changes relatively rapidly from a bright red to a dull red, which then makes its appearance generally less acceptable for consumers. The colours of strawberry spreads following several processing conditions were measured under different storage conditions. Additional sugar and colorant had only slight effects on the colour decay, while exclusion of oxygen and daylight did not affect this process. The only condition that clearly maintained the freshly processed appearance was storage at 4°C. Hexagonal bottles were filled with the strawberry spreads and their colour was repeatedly measured at the six sides of the bottles, using a Minolta chroma meter. Data were analysed using non-linear indexed regression analysis based on a logistic function for the three colour aspect of a*, b* and L*. This technology allowed the determination of the variation in these data in terms of improved reliability (R2adj, >90%). It also allowed better interpretation of the processes involved. All variations in the data could be attributed to technical variation.

Influence of phenol and sugar interactions on antioxidant activity of pomegranate juice

Nowadays, people are focusing on antioxidant-rich food due to its beneficial effect on health. Thus, the goal of this study was to investigate the interactions between catechin, quercetin, and gallic acid in the presence of sugars (sucrose and trehalose) in complex food matrix such as pomegranate juice. Antioxidant activity (AOA) was measured by three different methods, DPPH and ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP). In this paper, fundamental differences among used AOA measuring methods were confirmed, which can be traced back to interactions occurring between phenols and/or sugars. Even though addition of individual phenols increased AOA of mixtures, in the majority of binary and ternary mixtures antagonistic effects were observed. Positive effect of sugar addition was more pronounced in binary mixtures but the results were highly dependent on used AOA method.

Disaccharides: Influence on Volatiles and Phenolics of Sour Cherry Juice

The food industry is continuously developing ingredients, processing methods and packaging materials to improve the quality of fruit products. The aim of this work was to study the effect of sugars, a common ingredient in the food industry, on phenolics and volatiles of sour cherry juice. Sucrose, trehalose and maltose chemical isomers were chosen for this investigation. All sugars influenced the evaluated parameters. Samples with maltose addition had lower, while samples with sucrose and trehalose addition had higher anthocyanin content than the control sample. Generally, trehalose had a higher positive effect on volatiles with the desired flavor note.

Improving the quality of apple purée

The aim of the present study was to evaluate the effect of addition of 5% of apple peel powder (APP) and sugars (1, 5% of glucose, fructose, sucrose or trehalose) in apple purée on its phenolic composition and antioxidant activity (AOA). Apple purée samples were processed by freezing and freeze-drying. Apple purées containing APP showed higher phenolics, and AOA than the purées without APP. In freeze–dried samples the highest retention of individual polyphenols was achieved with addition of 1% of fructose or trehalose. However, in frozen samples the best impact on polyphenol retention had 5% of sucrose or trehalose. The results from this study showed the antioxidant potential of apple peel as a naturally-sourced antioxidants as well as a new insight into phenol–sugar interaction. These new findings could be of interest for the development of new food products rich in antioxidants which can improve human health.

Volatile profile of sour cherry puree as affected by sucrose and trehalose

ABSTRACT In this study, effect of sugars (sucrose and trehalose) and their amount on the volatile profile of sour cherry puree was evaluated. Results were compared to sour cherry puree without addition of sugars. Volatiles amount depended on type and amount of sugar. This indicated that the sugars showed an effect on flavour profile. Volatiles with the ethereal, alcoholic flavour note were present in the highest amount in the puree while with the addition of sugars, amount of those volatiles was lower. Sweet, floral volatiles were determined in higher amount when sugars were added in comparison to puree. Addition of sucrose did not have significant impact on the volatiles with sweet flavour note, while with addition of trehalose lower amount of those compounds were determined than in puree. Sweet, fruity and fresh, green volatiles were determined in higher amount in samples with the addition of sugars, especially when trehalose was added. Addition of sugar did not have impact on pungent volatiles.

Phenolics content and antioxidant activity of sour cherry extracts with sugar addition

Sour cherry puree was prepared with addition of sucrose or trehalose (5% and 10%). After stabilization of the mixture (puree with sugars), extracts were prepared and contents of phenolics and anthocyanin, polymeric colour percentage, and antioxidant activity were determined. Extracts were stored for 65 days at 4 °C. Control sample was extract of sour cherry puree without sugars. After extraction, extracts with 10% of sucrose or trehalose had higher phenolic content than the control sample. Anthocyanin content was higher in extracts with trehalose addition. During storage of extracts, samples with trehalose had higher retention of phenolic and anthocyanins than other samples. Addition of sucrose and trehalose as well as their amounts affected the stabilities of phenolics, anthocyanins, and antioxidant activity in sour cherry extracts.