Physico-chemical and antioxidant properties of six apple cultivars (Malus domestica) grown in Slavonia

The aim of this study was to compare the physico-chemical properties and antioxidant activity of six apple cultivars grown in Slavonia (Croatia). Apple firmness, total soluble solids (TSS), pH, total acid content (TAC), total phenolics (TP), anthocyanins (A) and antioxidant activity (AA) were measured in the apple cultivars Idared, Fuji, Gala, Granny Smith, Jonagold and Top Red Delicious. The TP, A and AA were measured in peel, flesh+peel and flesh tissues from the apple cultivars. The results showed significant differences in the composition of the apple cultivars. Firmness of Fuji apple was the highest and Jonagold was the lowest. The TSS varied from 10.95% (Gala) to 15.20% (Fuji), pH value was between 3.63 (Granny Smith) and 4.33 (Gala), and the TAC ranged from 0.10 (Gala) to 0.33 (Granny Smith). Within each cultivar, the TP, A content and AA were the highest in the peel, followed by the flesh+peel and the flesh. Apple peel had from 2.4 to 3.8 times greater AA and from 4.7 to 9.8 times greater TP compared with flesh, with lower values found in Gala and Top Red Delicious, and higher in Idared, respectively. The TP (g GAE/kg fresh matter) observed in the apple cultivars was between 0.54 (Jonagold) and 6.56 (Idared). The values of the A (mg/L) ranged from 0 (Granny Smith) to 166.70 (Idared). The highest AA (mmol TE/100mL) was observed in Top Red Delicious peel (7.54), while the lowest value was found in the flesh of Jonagold (1.32). The Pearson correlation analysis showed positively correlation between TP in peel, flesh+peel, and flesh tissues with their AA (r=0.891, α<0.05). These results can be of great value to genet icists, producers, food processing industry and consumers

APPLICATION OF Litsea cubeba TO IMPROVE SHELF-LIFE OF FRESH-CUT ‘PACKHAM’S TRIUMPH’ PEARS

Plant-derived natural products can be of interest as a source of alternatives to improve the shelf-life and the safety of food. Litsea cubeba has recently received much attention due to multiple functions as antibacterial, antifungal, insecticidal, antioxidant and anticancer agent. The application of Litsea cubeba essential oil (LC) in this investigation is one of the first experiments made in order to improve shelf-life of minimally processed fruits. The aim of this work was to investigate the effect of LC at different concentrations (50, 100 and 250 ppm), on shelf-life of fresh-cut pears ‘Packham’s Triumph’ variety. Colour of fresh-cut pears as well as, polyphenol content, antioxidant activity and flesh firmness of untreated and treated samples, were determined. Analysis were carried out immediately following oil treatments, and on 1, 7, 14 day of storage at 2 °C. Treatment with 50 ppm of LC was the most effective treatment to maintain colour of fresh-cut pears during 14 day of storage. Phenolic compounds and antioxidant activity in samples treated with solutions of LC remain stable during 14 day of storage. The lowest loss of firmness was detected in fresh-pears treated with 250 ppm LC. Essential oil of Litsea cubeba has promising application as a treatment of fresh-cut pears

With food to health : proceedings of the 9th International scientific and professional conference

Proceedings contains 7 original scientific papers, 8 professional papers and 1 review paper which were presented at "9th International Scientific and Professional Conference WITH FOOD TO HEALTH", organised in following sections: Nutrition, Dietetics and diet therapy, Food safety, Food analysis, Production of safe food and food with added nutritional value

The Effect of High Voltage Electrical Discharge on the Physicochemical Properties and the Microbiological Safety of Rose Hip Nectars

Although neglected as an industrial raw material, rose hip has been important for both nutritional and medical purposes for centuries. The main goal of this study was to propose a rapid and inexpensive non-thermal technique such as high voltage electrical discharge (HVED) to preserve valuable rose hip bioactive compounds, towards the development of high-quality products, including low-calorie products. The objective of this work was to evaluate the effects of HVED on the physicochemical properties and the microbiological safety of rose hip nectar formulations and, for comparison, on a pasteurised sample. Physicochemical analysis proved that rose hip pulp and the prepared nectars were valuable sources of polyphenols and ascorbic acid with high antioxidant activity. The HVED technique had minimal effects on the quality characteristics of the nectars under the different process conditions (50, 100 Hz; 10, 15, 20 min). In addition, the pasteurised nectar showed the greatest loss of ascorbic acid (54%) and phenolic compounds (40%). The microbiological quality of nectars was examined immediately after preparation/treatment and after 6 and 12 days of storage at 4 &deg;C. In addition to the pasteurised sample, HVED-treated rose hip nectar prepared from microwave-blanched puree with extended shelf life had satisfactory microbiological safety after storage

Detection of adulteration in honeys by differential scanning calorimetry

U radu je ispitana mogućnost utvrđivanja patvorenja meda poznatog botaničkog podrijetla pomoću diferencijalne motridbene kalorimetrije (DMK, engl. DSC). Uzorci monoflornih vrsta meda - bagrema, kadulje i kestena, i livade kao poliflorne vrste meda podvrgnuti su analizi kemijskog sastava, mjerenju boje, određivanju reoloških parametara, a proučavano je i njihovo termičko ponašanje pri niskim i visokim temperaturama. DMK krivulje poslužile su za dobivanje uvida u ponašanje ispitivanih vrsta meda u širokom temperaturnom području (od -100 do 220 °C), odnosno kao osnova za određivanje početne i srednje temperature staklastog prijelaza (Tg), promjene specifičnog toplinskog kapaciteta (cp) te izračunavanje entalpije taljenja (Hm). Odabranim uzorcima meda je u određenim udjelima (5, 10 i 20 %) dodan fruktozni sirup (kao moguće sredstvo za patvorenje meda) kako bi se ispitao utjecaj dodatka sirupa na termičko ponašanje različitih vrsta meda, odnosno da bi se istražilo kod koje količine sirupa je moguće utvrditi patvorenje meda. Obrada rezultata termičke analize pokazala je statistički značajnu razliku između nepatvorenog uzorka i patvorenih uzoraka meda kod svih udjela sirupa. Dodatak sirupa od 5 do 20 % je rezultirao u promjeni početne (engl. onset) i srednje (engl. midpoint) temperature staklastog prijelaza patvorenih uzoraka meda (snižavanje Tg vrijednosti) i u porastu vrijednosti entalpije taljenja. Promjena specifičnog toplinskog kapaciteta se nije pokazala dobrim parametrom za utvrđivanje prisutnosti sirupa. Mjerenje boje i određivanje reoloških svojstava patvorenih uzoraka meda poslužili su kao dodatne metode za utvrđivanje patvorenja meda.In this work, differential scanning calorimetry (DSC) has been used for detection of adulteration in Croatian honeys of familiar botanical origin. Samples of monofloral honeys (acacia, sage, chestnut) and meadow, as a polifloral honey type, have been subjected to chemical analysis, colour measurement, determination of rheological parameters, as well as determination of thermal behaviour. DSC scans were used to determine behaviour of honey types under study in a very broad temperature range (from -100 to 220 °C), i.e. as a base for determining onset and midpoint glass transition temperatures (Tg), change of specific heat capacity (cp) and enthalpy of melting (Hm). The effect of syrup addition (at 5, 10 and 20 %) in honey samples and detection of honey adulteration was investigated. Results of thermal analysis showed statistically significant difference between authentic and adulterated honeys. Adulteration of the honeys with 5-20 % fructose syrup addition caused changes in both Tg (decreasing Tg values) and Hm (increasing Hm values). The variation of the specific heat capacity (cp) did not appear to be good parameter for detection of added syrup, as a possible honey adulterant. Measurements of colour and rheological properties determination of adulterated honey samples served as additional methods for detection of honey adulteration

Detection of adulteration in honeys by differential scanning calorimetry

U radu je ispitana mogućnost utvrđivanja patvorenja meda poznatog botaničkog podrijetla pomoću diferencijalne motridbene kalorimetrije (DMK, engl. DSC). Uzorci monoflornih vrsta meda - bagrema, kadulje i kestena, i livade kao poliflorne vrste meda podvrgnuti su analizi kemijskog sastava, mjerenju boje, određivanju reoloških parametara, a proučavano je i njihovo termičko ponašanje pri niskim i visokim temperaturama. DMK krivulje poslužile su za dobivanje uvida u ponašanje ispitivanih vrsta meda u širokom temperaturnom području (od -100 do 220 °C), odnosno kao osnova za određivanje početne i srednje temperature staklastog prijelaza (Tg), promjene specifičnog toplinskog kapaciteta (cp) te izračunavanje entalpije taljenja (Hm). Odabranim uzorcima meda je u određenim udjelima (5, 10 i 20 %) dodan fruktozni sirup (kao moguće sredstvo za patvorenje meda) kako bi se ispitao utjecaj dodatka sirupa na termičko ponašanje različitih vrsta meda, odnosno da bi se istražilo kod koje količine sirupa je moguće utvrditi patvorenje meda. Obrada rezultata termičke analize pokazala je statistički značajnu razliku između nepatvorenog uzorka i patvorenih uzoraka meda kod svih udjela sirupa. Dodatak sirupa od 5 do 20 % je rezultirao u promjeni početne (engl. onset) i srednje (engl. midpoint) temperature staklastog prijelaza patvorenih uzoraka meda (snižavanje Tg vrijednosti) i u porastu vrijednosti entalpije taljenja. Promjena specifičnog toplinskog kapaciteta se nije pokazala dobrim parametrom za utvrđivanje prisutnosti sirupa. Mjerenje boje i određivanje reoloških svojstava patvorenih uzoraka meda poslužili su kao dodatne metode za utvrđivanje patvorenja meda.In this work, differential scanning calorimetry (DSC) has been used for detection of adulteration in Croatian honeys of familiar botanical origin. Samples of monofloral honeys (acacia, sage, chestnut) and meadow, as a polifloral honey type, have been subjected to chemical analysis, colour measurement, determination of rheological parameters, as well as determination of thermal behaviour. DSC scans were used to determine behaviour of honey types under study in a very broad temperature range (from -100 to 220 °C), i.e. as a base for determining onset and midpoint glass transition temperatures (Tg), change of specific heat capacity (cp) and enthalpy of melting (Hm). The effect of syrup addition (at 5, 10 and 20 %) in honey samples and detection of honey adulteration was investigated. Results of thermal analysis showed statistically significant difference between authentic and adulterated honeys. Adulteration of the honeys with 5-20 % fructose syrup addition caused changes in both Tg (decreasing Tg values) and Hm (increasing Hm values). The variation of the specific heat capacity (cp) did not appear to be good parameter for detection of added syrup, as a possible honey adulterant. Measurements of colour and rheological properties determination of adulterated honey samples served as additional methods for detection of honey adulteration

Effect of baking and steaming on physicochemical and thermal properties of sweet potato puree preserved by freezing and freeze-drying

Thermal treatments could be one of the hurdles in applications of sweet potato purees for food different products formulation. Sweet potato purees (SPP) were prepared from raw, baked and steamed roots and they were preserved by freezing and freeze-drying. The effects of baking and steaming on thermal properties (melting temperature-Tm, melting transition energy - ΔH, and glass transition temperatures - Tg) of sweet potato (cultivar Beauregard), were measured by means of a Differential scanning calorimetry (DSC). The SPP made from baked roots had higher total and soluble solids (20.32 and 18.95%, respectively) than SPP made from raw and steamed roots. It can be also noticed that starch content was reduced by steaming and baking which reflected on amount of total and reducing sugars. The increase of reducing sugars level in baked SPP for 3.78% and steamed for 0.86% SPP was the result of yielding the maltose. The chemical changes of SPP also influenced the thermal behavior such that SPP prepared from baked sweet potato roots had the lowest initial freezing point (-2.80 °C) followed by SPP prepared from steamed (-2.63 °C) and raw (-0.71 °C) roots. The highest energy for melting (transition) was needed for SPP prepared from raw potato roots followed by steamed and baked roots, -103.79, -103.63, and -102.90 J/g, respectively. The glass transition in freeze-dried SPP prepared from raw roots was not detected. However, in the freeze-dried SPP prepared from baked and steamed roots the glass transition was detected in the range of 39 and 42 °C but with no significant difference (p > 0.05)