Antioxidant capacity and functionality of oleaster (Elaeagnus angustifolia L.) flour and crust in a new kind of fruity ice cream

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Antioxidant capacity and functionality of oleaster (Elaeagnus angustifolia L.)

ﬂour and crust in a new kind of fruity ice cream

Article in International Journal of Food Science & Technology · August 2014

DOI: 10.1111/ijfs.12637 CITATIONS 54 READS 1,280 7 authors, including:

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Original article

Antioxidant capacity and functionality of oleaster (Elaeagnus

angustifolia L.) flour and crust in a new kind of fruity ice cream

Song€ul Cßakmakcßı,1* Elif F. Topdasß,1Pınar Kalın,2Hatice Han,2Pınar Sßekerci,1,3Leyla P. K€ose2&

_Ilhami G€ulcßin2,4

1 Department of Food Engineering, Faculty of Agriculture, Atat€urk University, 25240 Erzurum, Turkey

2 Department of Chemistry, Faculty of Sciences, Atat€urk University, 25240 Erzurum, Turkey

3 Department of Food Engineering, Ardahan University, Ardahan, Turkey

4 Zoology Department, College of Science, King Saud University, 11451 Riyadh, Saudi Arabia (Received 5 April 2014; Accepted in revised form 15 July 2014)

Summary In this study, the inﬂuence of milled crust and ﬂour from oleaster (Elaeagnus angustifolia L.) separately

added at different levels (1%, 2% and 3%) on the physical, chemical, sensory, colour properties and anti-oxidant properties of ice creams were investigated. The increment of crust and flour level caused an increase of dry matter, acidity, viscosity, first dripping, complete melting and vitamin C content. Flour increased overrun values in ice cream. Our results indicated that lyophilised oleaster extracts contain remarkable phenolic compounds. It was observed that lyophilised oleaster extracts exhibited a moderate

in vitro antioxidant capacity. The addition of oleaster ﬂour and crust positively aﬀected sensory

proper-ties. The sensory results showed that ice cream containing 2% oleaster flour was the highest scored by the panellists. Oleaster flour and crust increased the sweetness of ice cream samples. These results showed that considerable nutritive and functional improvement could be attained by the addition of oleaster flour to ice cream formulation so that it could be used as natural antioxidants in ice cream as a source of flavour with complacency.

Keywords Antioxidant activity, Elaeagnus angustifolia, food properties, ice cream, oleaster.

Introduction

Ice cream is a complex food matrix, containing fat, proteins, sugars, minerals, polysaccharides air bubbles and ice crystals (Goff et al., 1999). Good quality ice cream production largely depends on ice cream formu-lation as well as the processing parameters. Due to using many different fresh fruits, fruit juices, fruit products, probiotics and other additives and process-ing technologies, ice cream production is an important and rapidly developing technology that has become a profitable industry because of recent advances. There-fore, freezing in all seasons produced a significant dairy product. Research shows that a mixture of ice cream added additives affects nutritional value and sensory quality (Prindiville et al., 1999; Turgut & Cak-makci, 2009; Sagdic et al., 2012).

Oleaster (Elaeagnus angustifolia L.) is a tree, and its fruit grows in various climatic and environmental con-ditions. It is also known as Russian olive, and native to western and central Asia, from southern Russia and

Kazakhstan to Mediterranean environment, Turkey and Iran (Anonymous, 2014). Fruits are valuable in terms of health and can be used as natural antioxidants (Durmaz, 2012), and for their natural colour. Also as used in the fields of medicine and pharmacy and in Asia and in Europe is certified (G€ulc€u & Cßelik Uysal, 2010). There are no toxic substances in oleaster fruits. Oleaster is advised to be consumed by the people who have kid-ney disorders. It can be used as a diuretic and fever-reducing drug (Baytop, 1984), for preventing intestine disorders and mouth rust, and its fruit extracts can be used as anti-inflammatory and analgesic (Ahmediani et al., 2000) in traditional medicine. The oleaster fruit contains 12.33% protein (Akbolat et al., 2008), vita-mins (tocopherol, carotene, vitamin C, and thiamine), mineral substances (calcium, magnesium, potassium, iron, and manganese; Boudraa et al., 2010). Dominant sugars are in the plant fructose and glucose (Ayaz & Bertoft, 2001). The size of the fruit is the same as olives and skin is hard, yellowish-brown in colour. The total production of oleaster in Turkey is about 6000 tons (Durmusß & Yigit, 2003). In Turkey, the dry fruit is usually consumed as an appetiser during autumn and

*Correspondent: Fax: +90-442-2315878;

e-mails: songulcakmakci@hotmail.com; cakmakci@atauni.edu.tr

International Journal of Food Science and Technology 2015,50, 472–481

doi:10.1111/ijfs.12637

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winter. It is rich in nutrients and antioxidant com-pounds. For this reason, it is used in food products

(Boudraa et al., 2010; Cansev et al., 2011; Cß akmakcßı,

2012). Due to many beneficial effects of oleaster, this study aims to investigate the possibilities of producing ice cream with its flour and crust. The consumption of oleaster fruit is not very common, although it is very ben-eficial. This study is useful for contributing to its con-sumption. The aim of this study was to compare the quality characteristics of ice cream samples that contain the flour and crust of oleaster as a new ingredient, from other well-known additives, and also investigate the effect of oleaster on quality characteristics, appearance, colour and sensory properties of a typical type of ice cream. The other aim of this study was to investigate the possibility of using oleaster flour and crust in the produc-tion of ice cream and contribute to the manufacturing of a new nutritional and functional ice cream. We thought that oleaster’s nutritive value, smoothness, pleasant fla-vour and floury properties may be used as a suitable source of natural additive in ice cream production to enhance nutritional values, sensory characteristics, anti-oxidant capacities, natural colour, use less sugar and to improve physicochemical properties. Due to the excessive amount of sugar content, sucrose may be used less. Also the results of this study will provide additional informa-tion to the limited literature about oleaster.

Materials and methods Materials

Cream and cows’ milk were obtained from the

Research and Application Farm of Atat€urk

Univer-sity, Turkey. The oleaster (E. angustifolia L.) was pur-chased from a supermarket in Erzurum, Turkey and sorted visually for colour and physical damage. The oleasters were washed by immersion in water in a ﬁlter

and then dried in a drying oven at 60 °C for 30 min

(Binder D-78532, Tuttlingen, Germany). Then, the crusts were peeled by hand. The flour and crust por-tions were separated (using a coffee machine). Flour and crust dry matter (%), ash (%) and vitamin C (mg per 100 g) content were found, respectively, as follows: 88.1 and 90.4; 2.09 and 2.37; 21.5 and 13.9. The milled crust and flour of oleaster were used for the study. They are extracted separately from the fruit. Sugar, salep and emulsifier (mono- and di-glycerides) were obtained from local market. Skimmed milk powder was supplied by Pinar Dairy Products Co. (Izmir, Tur-key).

Ice cream mixes and ice creams preparation

Seven diﬀerent ice cream samples were produced, including the Control group, in the Pilot Dairy

Factory of Food Engineering Department, Atat€urk University (Erzurum, Turkey). The ice cream mix sam-ples were prepared with the fat content of the milk adjusted to 6%. This ratio was obtained with 38% w/v fat content cream. The milk was divided into seven equal parts of 4.0 kg. The composite ingredients in ice cream formulations (Table 1) were added for each mix. After addition of ingredients, the prepared mixes

were stirred consistently and pasteurised at 85°C for

25 s and were rapidly cooled to 4°C and left to

remain at a constant temperature for 24 h to be aged. They were frozen in the ice cream machinery (5 °C) (Ugur Cooling Machineries Co., Nazilli, Turkey) and

hardened at22 °C for 1 day. Ice creams were stored

at18 °C until the time of analysis. The overall

exper-imental procedure was duplicated. Analytical procedures

The viscosities of ice cream mixes were determined

after 24 h of storage at 4°C using a digital Brookﬁeld

viscometer, Model DV-II (Brookﬁeld Engineering

Laboratories, Stoughton, MA, USA). Twenty readings as centipoise (cP) were taken per sample at 30 s

inter-vals by camera recording ( €Ozer et al., 1997). A

stan-dard 100-mL cup was used for Overrun (OR) analysis. The ice cream mixes OR values were calculated using the formula (Marshall & Arbuckle, 1996). The method of Guven & Karaca (2002) was used for measuring complete melting and ﬁrst dripping times of ice cream samples. The chemical parameters evaluated were pH, total solids (gravimetric method), protein (Kjeldahl method), ash (AOAC, 2005). Fat (Gerber method) and

titratable acidity (°SH) of ice cream samples were

determined according to G€ursel & Karacabey (1998). Several methods have been used for vitamin C

analysis. These methods can be classiﬁed as

spectroscopic, electrochemical, chromotographic and

electrophoretic methods. In this research, L-Ascorbic

acid; 2,3-endiol-L-gulonic acid-g-lactone (vitamin C)

Table 1 The composite ingredients in mix formulations

Ingredients Percentage (w/w)

Sugar 18.0

Skim milk powder 4.8

Salep (stabiliser) 0.7

Emulsifier (mono- and diglycerides) 0.2 Other ingredients

Control -(without oleaster- sample A) 0.0 Oleaster flour (sample B) 1.0 Oleaster flour (sample C) 2.0 Oleaster flour (sample D) 3.0 Oleaster crust (sample E) 1.0 Oleaster crust (sample F) 2.0 Oleaster crust (sample G) 3.0

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contents of ice cream samples were determined as described by Cemeroglu (2010). The experiments were carried out in duplicate.

Colour measurement

Colour measurements were performed with a Minolta colorimeter CR-200 (Minolta Camera Co., Osaka, Japan). The colour of ice cream samples was obtained from measuring L* (brightness; 0: black, 100: white), a*

(+: red; : green), b* (+: yellow; : blue) values by

reﬂection. The colorimeter was calibrated with the

stan-dard white plate. The hue angle values of 0°, 90°, 180°,

270° and 360° represents the colours red, yellow, green, blue and red, respectively (Chunthaworn et al., 2012). Hue angle (H°) and colour saturation (C) was deter-mined using the formula by Mendoza et al. (2006). Antioxidant methods

The lyophilised water extraction of a plant was previ-ously described (Bursal & G€ulcßin, 2011). Fifty gram of oleaster flour or crusts were ground into a fine powder in a mill, separately. Then both parts were mixed with 500 mL of boiling water and stirred for ten minutes. The mixture was filtered over Whatman paper (No. 1). The filtrates were frozen and lyophilised in a

lyophili-sator at 5 mmHg pressure at50 °C (Labconco model

117; Labconco Corporation, Kansas City, MO, USA). Finally, the lyophilised oleaster extracts (Flour-LOE and Crust-LOE) were placed in two plastic bottles and

stored at20 °C until used in antioxidant assays.

The total phenolics in Flour-LOE and Crust-LOE were calculated according to the modified version of the procedure described by Slinkard & Singleton (1977) using by Folin-Ciocalteu phenolic reagent. Results are reported in gallic acid equivalents (De Beer et al., 2004). Total flavonoids determination of Flour-LOE and Crust-Flour-LOE was performed according to G€ulcßin et al. (2011). Total flavonoids quantity was cal-culated using quercetin as standard (r2: 0.9820):

Absorbanceðk415Þ ¼ 0:0011 Total Flavonoid ðlgÞ

The content of ﬂavonoids in Flour-LOE and Crust-LOE was calculated from above standard curve pre-pared using quercetin and expressed as micrograms of quercetin equivalents (QE). The reducing antioxidant power of Flour-LOE and Crust-LOE was carried out

with the method of Oyaizu (1986). Cu2+-reducing

abil-ity of Flour-LOE and Crust-LOE was determined according to the method of Apak et al. (2004) with slight modiﬁcations (Bursal et al., 2013). Absorbance was measured at 450 nm after 30 min against a

reagent blank. Increased absorbance indicates

increased reduction capability of Flour-LOE,

Crust-LOE or standards. The determination of the

total antioxidant activity (FRAP assay) in the Flour-LOE and Crust-Flour-LOE, the method of Benzie & Strain

(1996) was slightly modiﬁed (Cßetinkaya et al., 2012).

Another reducing power assay used in this study is ferric-reducing antioxidant power (FRAP). In DPPH scavenging assay (Blois, 1958), the antioxidants were able to reduce the stable radical DPPH to the yellow coloured diphenyl-picrylhydrazine. This assay was used to assess the DPPH free radical scavenging capacity of Flour-LOE and Crust-LOE previously

described by Balaydın et al. (2010). The DMPD˙+

scavenging ability of Flour-LOE and Crust-LOE was performed according to Fogliano et al. (1999).

Sensory analysis

The sensory properties of the ice cream samples were evaluated according to the method suggested by Body-felt et al. (1988). The sensory properties of the ice cream samples were assessed by ﬁfty consumer panel-lists who were experienced and familiar with ice cream and oleaster. Coded ice cream samples were stored at

the 18 °C for 2 days before analysis. The hardness

of ice cream samples was tested at a serving

tempera-ture of 10 °C. The tests were conducted at a

conve-nient central location (Erzurum, Turkey), in the homes (by consumers) or by neighbours or students and teaching staff of Atat€urk University Food Engineering Department (Erzurum, Turkey) or in Atat€urk Univer-sity Science Faculty Department of Biochemistry (stu-dents and teaching staff). The ice cream samples (approximately 30 g) were placed on special white ice cream plates. Each panel member assessed the ice cream samples for seven sensory attributes including colour–appearance, gumming structure, texture, fla-vour, sweetness, resistance to melting and overall acceptability. All sensory attributes were recorded on point scales with 1 (poor) to 9 (excellent). Warm water was also provided to the panel members to cleanse their palates between samples.

Statistical analysis

Statistical analysis was carried out using SPSS 17.0 (SPSS Inc., Chicago, IL, USA) software. Data were subjected to a multiple analysis of variance and the average values were compared using the Duncan’s Multiple Range Test, at the P< 0.05 signiﬁcance level. Results and discussion

Physical and chemical properties

Viscosity is an important characteristic of ice creams because it aﬀects body and texture. As shown in Fig. 1, the apparent viscosity of other ice cream

International Journal of Food Science and Technology 2015

Ice cream with oleasterS. Cßakmakcßı et al. 474

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samples was increased signiﬁcantly when compared to

the Control group (at 20 and 50 r.p.m.) (P < 0.05).

However, increasing is not the same for all samples. Apparent viscosity values increased with the increasing concentration of crust or flour of oleaster. It was also found that the samples containing the crust of oleaster increased the apparent viscosity more than other sam-ples. According to Fig. 1, the highest viscosity value was found in ice cream mix containing 3% crust of oleaster (18 364 cP at 20 r.p.m., 9484 cP at 50 r.p.m.), while the lowest was in the Control sample (9382 and 5613, respectively). The sample with 3% oleaster flour had an average of 17 214 cP at 20 r.p.m. and 9432 cP at 50 r.p.m. However, these values are not as high as the sample including 3% crust of oleaster. It can be speculated that high content of dietary fibre increases the viscosity. A similar result was reported by Hwang

et al.(2009) in grape wine lees added in ice cream.

Overrun value identifies the final product’s structure, as the existence of air gives the ice cream an enjoyable light texture (Sofjan & Hartel, 2004). The percentage of overrun among mixes was significantly different

(P< 0.05). The overrun values of samples ranged from

26.50% to 40.98%. These low values are quite reason-able because in the event that there is an extremely increase in the overrun value, the ice cream lacks body and becomes soft (Uzomah & Ahiligwo, 1999). As shown in Fig. 2, the overrun values of samples con-taining (flour of) oleaster were higher than other sam-ples. The lowest overrun value was achieved by 3% crust addition (26.50%), while the highest viscosity value was provided by this sample. It can be specu-lated that crust addition decreased the overrun value because it raised the viscosity of ice cream samples. Similarly, El-Samahy et al. (2009) who studied produc-ing ice cream with concentrated cactus pear pulp, Der-visoglu (2006) who studied the effect of hazelnut flour addition to ice cream properties and Temiz & Yesßilsu (2010) who studied the effect of pekmez addition on the physical, chemical and sensory properties of ice

cream reported the decrease of overrun values for ice cream samples. Besides overrun, the melting properties are also important variables for evaluating an ice cream product and associated processing (Arbuckle, 1986). As shown in Fig. 3, flour of oleaster added samples (B, C, D) had the longest complete melting times (4140, 4380 and 4890 s, respectively) compared with the Control (A) (3870 s) and crust of oleaster added samples (E, F, G) (3630, 3810 and 3960 s). As can be seen from Fig. 3, the first dripping time values of ice cream samples ranged from 750 to 1290 s. The first dripping times of crust or flour added samples got longer as the fruit content increased (P< 0.05). Addi-tionally, ice creams made with 39–41% overrun (which were crust of oleaster added samples) melted more a b d e c e e a b e ef c d f 0 5000 10 000 15 000 20 000 A B C D E F G Visco sity (cP) Samples 20 rpm 50 rpm

Figure 1 Viscosity values of ice cream mixes. Different letters above the bars indicate significant differences by Duncan multiple

comparison test (P< 0.05). b e _d d c b _a 0 5 10 15 20 25 30 35 40 45 A B C D E F G Samples Overrun (%)

Figure 2 Overrun values of ice cream samples. Different letters above the bars indicate significant differences by Duncan multiple

comparison test (P< 0.05). c de e b a b d cd de e a b c de 0 1000 2000 3000 4000 5000 6000 A B C D E F G Samples Time (s)

First dripping Complete melting

Figure 3 First dripping and complete melting times of ice cream samples. Diﬀerent letters above the bars indicate signiﬁcant

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rapidly than others. These results are conﬁrmed by Flores & Goﬀ (1999) who showed that increase at overrun caused a slight decline in mean ice crystal size. According to Sofjan & Hartel (2004), these actions may be concerned with the change in heat transfer rates from the ice cream upon increased aeration.

The total solids, pH, titratable acidity, protein, fat and ash content results of ice cream samples are shown in Table 2. The highest total solid value was found in ice cream containing 3% flour of oleaster (D), while the lowest was in the Control sample (A). The flour and crust of oleaster have higher rates dry matter 88.1% and 90.4%, respectively (section Mate-rials) compared to control ice cream samples. There-fore, the increases in rates caused to increase dry matter in the ice cream samples. In comparison with the control sample, increases in the dry matter con-tent of ice cream were 1.32% and 0.92% for 1%; 3.40% and 1.87% for 2%; 3.62% and 2.67% for 3% oleaster flour and crust-added samples, respec-tively. Ash content of samples with added oleaster slightly increased. Therefore, nutritional values of ice cream increased with added flour and crust of oleaster.

There was no signiﬁcant diﬀerence in the ash and fat contents achieved for the ice creams. The titratable

acidity of samples was in the range of 0.25–0.37%. An

increase in the titratable acidity was found in the sam-ples when increase the concentration of ﬂour or crust of oleaster was compared with the Control sample. As seen in Table 2, ﬂour and crust of oleaster addition caused decreases in the protein and fat content as the relative of ice creams compared to the Control. Hwang

et al. (2009) (studied with grape wine lees) and Sagdic

et al. (2012) (studied with elegiac and gallic acid and

some extracts obtained from grape seed and pepper-mint with Lactobacillus casei Shirota) reported that the addition of phenolic substances caused a decre-ment in pH values of ice cream sample due to the acidic nature of phenolic substances.

Vitamin C is important for fruity ice creams, which have high vitamin C content. Average vitamin C

val-ues for ﬂour and crust of oleaster were 21.50 0.13

and 13.97 0.15 mg per 100 g, respectively. These

values decreased in ice cream samples because of low fruit concentration (1%, 2% and 3%) and processing conditions such as temperature and process time. According to Imeh & Khokhar (2002) and Kalt (2005), factors such as physiological maturity, harvest factors, storage status and analysis method utilised contribute to the vitamin C content in fruits. Figure 4 clearly shows that the addition of ﬂour or crust of ole-aster signiﬁcantly increased the vitamin C content of

ice creams compared to the Control sample (P < 0.05).

The highest vitamin C content was found in ice cream containing 3% ﬂour of oleaster (D, 9.33 mg per 100 g) while the lowest was in the Control (A, 2.95 mg per 100 g). The increase was also observed with E, F, G samples containing 1%, 2%, 3% crust of oleaster, although the increase was not as high as ﬂour contain-ing samples.

Table 2 Eﬀect of the addition of oleaster on the gross chemical composition of ice creams

Ice cream

samples Total solids (%) Protein (%) Fat (%) Ash (%) Titratable acidity (°SH) pH

A 40.02 0.07d 4.96 0.20b 5.40 0.14a 1.09 0.03 0.25 0.11e 6.68 0.03a B 40.55 0.06c 4.60 0.25a 5.15 0.07ab 1.09 0.05 0.29 0.30c 6.64 0.02b C 41.38 0.48a 4.62 0.55a 5.00 0.14b 1.12 0.03 0.31 0.12c 6.50 0.04c D 41.47 0.10a 4.86 0.32b 4.90 0.14b 1.13 0.01 0.35 0.11b 6.46 0.04d E 40.39 0.75cd 4.68 0.56a 4.95 0.07b 1.08 0.07 0.30 0.54d 6.62 0.03b F 40.77 0.05bc 4.86 0.32b 5.15 0.07ab 1.09 0.02 0.35 0.60b 6.51 0.07c G 41.09 0.53ab 4.86 0.62b 5.05 0.07b 1.10 0.04 0.37 0.11a 6.39 0.07e A: Control without oleaster, B: 1% (w/w) flour of oleaster added, C: 2% (w/w) flour of Angustifolia added, D: 3% (w/w) flour of oleaster added, E: 1% (w/w) crust of oleaster added, F: 2% (w/w) crust of oleaster added, G: 3% (w/w) crust of oleaster added.

Mean values followed by different letters in the same column are significantly different (P < 0.05).

a c d e b c d 0 2 4 6 8 10 A B C D E F G Vitamin C (mg 100g –1)

Ice cream samples

Figure 4 Vitamin C content of ice cream samples. Different letters above the bars indicate significant differences by Duncan multiple

comparison test (P< 0.05).

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Colour in ice creams

Colour is the most important parameter in consumer choice of ice creams. Therefore, colour parameters were analysed to determine the effect of different concentrations of flour and crust of oleaster in ice

cream samples. The colour values (L*, a*, b*, H° and

C*) of the samples are shown in Table 3. L* values of

samples decreased signiﬁcantly (P < 0.05) in all

sam-ples when compared to the Control group. As shown in the table, the highest L* value (90.02) was

moni-tored in the Control sample, while the lowest L* value

(77.18) was in 3% crust of oleaster added sample.

According to the results, sample luminosity (L*)

decreases with the increase in concentration of oleaster flour and crust. This situation is due to the brown pig-ments in crust and flour. Supplement type and concen-tration affected a* values of all ice cream samples significantly (P< 0.05). The highest and lowest a* val-ues were detected in 3% crust of oleaster added and the Control ice cream samples with values of 2.04 and 2.77, respectively. A disparate trend was observed in the b* values. The highest value was observed in sam-ple D, while the lowest was in samsam-ple G. In this case, it can be said that samples containing oleaster flour became more yellow and red. On increasing the addi-tion of oleaster flour or milled crust to ice cream sam-ples, the ice cream colour turned yellowish-orange. They served as a natural colour additive. However, ice creams containing oleaster flour had more homoge-neous texture. Sagdic et al. (2012) found that the phe-nolic substance addition caused a significant change in the colour characteristics of ice creams compared to the Control sample. The hue angle of Control samples represents a colour in the yellow/green region (hue angle between 90 and 180). However, when the crust of oleaster was added, the samples region shifted towards the red/yellow region (hue angle between 0 and 90). According to Calvo (2004) the Chroma value (C*) indicating the degree of saturation, purity or

intensity of visual colour. The C* values of ice creams

were in the range of 7.98–10.24.

Antioxidant properties

The human diet contains diﬀerent compounds that possess antioxidant activities. These plants include numerous phenolic or polyphenolic compounds. Phe-nolic compounds have been suggested to scavenge reactive oxygen species (ROS) and reactive nitrogen species because of their structural properties. They consist of one or more hydroxyl groups (–OH) bonded directly to an aromatic hydrocarbon ring. They natu-rally occur in almost all plant materials. Also, these secondary plant metabolites are found in food and pharmaceutical products of plant origin. Phenolic compounds are considered as an integral part of both

human and animal diets (G€ulcßin et al., 2004). Our

results indicated that Flour-LOE and Crust-LOE con-tain remarkable phenolic compounds. For determining total phenolic contents, standard graphic calibration curves were obtained using known quantities of stan-dard gallic acid. The phenolic compounds in 1 mg of Flour-LOE and Crust-LOE was found as 27.78 and

31.11lg GAE, respectively.

Conversely, flavonoids are the most common group of polyphenolic compounds in the human diet. They are very effective antioxidants and they protect against cardiovascular disease by reducing the oxidation of low-density proteins (Thompson & Moldeus, 1988). They are commonly found in fruits and vegetables and have been linked to reduce risk of mortality from the coronary heart diseases (Wang et al., 2011). At the same time, total flavonoid amount in 1 mg of Flour-LOE and Crust-Flour-LOE was determined

spectrophoto-metrically and found to be 36.36 and 32.73lg QE,

respectively. These ﬁndings clearly demonstrate that there is a positive correlation between the total pheno-lics and ﬂavonoid contents in Flour-LOE and Crust-LOE and antioxidant activity.

Table 3 Comparison of colour parameters for ice creams associated with diﬀerent pretreatments

Ice cream samples L* a* b* H° C* A 90.02 0.18g 2.77 0.09a 9.66 0.02d 106.00 0.71f 10.05 0.04d B 86.16 0.07f 1.01 0.05b 8.99 0.11c 96.35 0.07e 9.05 0.10b C 85.20 0.19e 0.18 0.03c 9.57 0.05d 91.05 0.21d 9.57 0.05c D 82.23 0.22c 0.38 0.06d 10.24 0.21e 87.95 0.50c 10.24 0.21d E 82.16 0.52d 0.36 0.04d 8.21 0.05b 90.40 0.28d 8.21 0.05a F 78.87 0.12b 1.13 0.14e 7.96 0.01b 82.00 0.99b 8.04 0.04a G 77.18 0.14a 2.04 0.11f 7.57 0.16a 75.30 0.28a 7.98 0.04a A: Control (without oleaster) B: 1% (w/w) flour of oleaster added, C: 2% (w/w) flour of oleaster added, D: 3% (w/w) flour of oleaster added, E: 1% (w/ w) crust of oleaster added, F: 2% (w/w) crust of oleaster added, G: 3% (w/w) crust of oleaster added.

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In our study, the antioxidant activity of Flour-LOE and Crust-LOE using some bioanalytical methods

(G€ulcßin, 2012). As seen in Table 4, Flour-LOE and

Crust-LOE had marked ferric ions (Fe3+) reducing

power. In this method, it was found that reducing power of Flour-LOE (0.149) and Crust-LOE (0.128) was close to trolox (0.309) but lower than that of

BHA (1.863), BHT (1.952), a-tocopherol (0.782). The

reducing power of Flour-LOE, Crust-LOE and stan-dard antioxidants decreased in the following order:

BHT BHA > a-Tocopherol > Trolox > Flour-LOE

≥ Crust-LOE. Also, cupric ion (Cu2+

) reducing power of Flour-LOE, Crust-LOE and standard compounds decreased in the following order: Crust-LOE (0.035) < Flour-LOE (0.059) < trolox (0.307) < a-Tocopherol

(0.328) < BHA (0.452) BHT (0.458). According to

results obtained from FRAP assay (Table 4), reducing

power of Flour-LOE, Crust-LOE and standards

decreased in the following order: Trolox (0.378)

< Crust-LOE (0.399) < Crust-LOE (0.419)<

a-Tocopherol (1.323)< BHT (2.140) BHA (2.163). In

all of reducing power assays, higher absorbance values indicate higher reducing ability.

The chromogenic DPPH and DMPD scavenging assays are commonly used for determination of the

radical scavenging ability of various samples (G€ulcßin,

2008). DPPH is a stable free radical and accepts an electron or hydrogen radical to become a stable dia-magnetic molecule, which is widely used to investigate

radical scavenging activity (G€ulcßin, 2012). In DPPH

radical scavenging assay, antioxidant molecules or extracts react with DPPH radicals and convert them to yellow coloured 1,1-diphenyl-2-picryl hydrazine

(DPPH2). The degree of discoloration indicates the

scavenging potential of the antioxidant (Blois, 1958;

G€ulcßin, 2012). The extract was capable of neutralising

the DPPH free radicals via hydrogen donating activity by diﬀerent concentrations of Flour-LOE and

Crust-LOE. The IC50 was calculated as 34.65lg mL1 for

Flour-LOE and 34.72lg mL1 Crust-LOE.

Con-versely, this value was found as 5.78, 13.33, 40.77 and

4.56 lg mL1 for BHA, BHT,a-Tocopherol and

Trol-ox, respectively (Table 5).

Another improved decolourisation method for mea-suring the radical scavenging activity of food samples,

N,N-dimethyl-p-phenylenediamine (DMPD) radicals

scavenging is developed (G€ulcßin, 2012). DMPD radical

cation (DMPD˙+) is generated through a reaction

between DMPD and potassium persulphate (K2S2O8)

and is subsequently reduced in the presence of

hydro-gen-donating antioxidants. The principle of the

DMPD˙+ scavenging assay is that DMPD can form a

stable and coloured radical cation (DMPD˙+

) at acidic pH and in the presence of a suitable oxidant solution. As seen in Table 5, D DMPD radical scavenging by Flour-LOE, Crust-LOE and standard antioxidants

(BHA, BHT,a-Tocopherol and trolox) increased in the

following order:a-Tocopherol (6.86 lg mL1) <

Flour-LOE (7.45lg mL1) Crust-LOE (7.48 lg mL1)

< BHA (8.77lg mL1)< Trolox (9.45lg mL1)

< BHA (10.51 lg mL1_{). Lower IC}

50 values indicate

high DMPD˙+scavenging ability.

Sensory properties of ice creams

The sensory properties of ice cream samples are shown in Fig. 5. The addition of the oleaster flour and crust as additives significantly affected the sensory analysis of the ice cream samples. Colour and appearance scores were significantly different, between 7.17 and 7.70. The highest score was determined in sample B. However, B, D, E, F and G samples are not different statistically. Oleaster flour and crust gave a slight yel-lowish brown colour to ice cream that was desirable for some panellists. The samples containing oleaster flour and crust showed relatively high scores in terms of organoleptic characteristics such as gumming struc-ture, texstruc-ture, flavour, sweetness and resistance to melt-ing compared to the Control group. The highest values for colour had B, D, E, G and F samples, respectively. The highest values for gumming structure had D samples. The Control group had the lowest value. Gumming scores were significantly different

(P< 0.05), between 5.61 and 7.06. Panellists reported

Table 4 Ferric ions (Fe3+) and cupric ions (Cu2+) reductive

poten-tial and FRAP assay of Flour-LOE, Crust-LOE and reference

antioxidants at the same concentrations (20lg mL1)

Antioxidants

Fe3+ -Fe2+ reducing assay

Cuprac

assay FRAP assay

BHA 1.863 0.452 2.163 BHT 1.952 0.458 2.140 a-Tocopherol 0.782 0.328 1.323 Trolox 0.309 0.307 0.378 Flour-LOE 0.149 0.059 0.419 Crust-LOE 0.128 0.035 0.399

Table 5 The half-maximal scavenging concentration (IC50lg mL1)

values of Flour-LOE, Crust-LOE and standards on DPPH and DMPD radicals Antioxidants DPPH˙ scavenging assay DMPD˙+ scavenging assay BHA 5.78 8.77 BHT 13.33 10.51 a-Tocopherol 40.77 6.86 Trolox 4.56 9.49 Flour-LOE 34.65 7.45 Crust-LOE 34.72 7.48

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that control samples had a mild texture and melted easily. Also, the addition of oleaster flour and crust positively affected the gumming structure, flavour, sweetness and resistance of melting scores. The highest flavour score was determined in sample C. The addi-tion of oleaster flour and crust increased the sweetness of ice cream samples. The highest sweetness score was determined in sample D followed by C and B, respectively. It was also observed that the addition of oleaster flour and crust produced sweeter taste in the ice cream samples. Panellists indicated that as oleaster flour and crust ratio increases in the samples, they felt sourness during the sensory analysis; especially the crust was more sour. These samples were favoured by the panellists, due to extra sweetness of flour and crust, it balanced taste of ice cream samples. But, panellists noted, the crust of oleaster, a thin membrane that is felt in the mouth as a foreign substance, was disagreeable. The increase in the level of flour and crust increased the resistance to melting. The highest score was determined

in sample D. Oleaster ﬂour signiﬁcantly raised

(P< 0.05) the overall acceptability of ice cream in 3% and 2% concentrations studied, respectively compared with the Control group.

Conclusions

The addition of oleaster flour and crust significantly affected the physical, chemical, colour, sensory and antioxidant characteristics. The samples containing oleaster flour were preferred by the panellists in respect to sensorial properties. Given oleaster flour’s nutritive value, pleasant flavour, it may be used as a suitable source of natural additive in ice cream pro-duction to enhance nutritional values, antioxidant capacities, natural colour, use of less sugar and improvement of physicochemical properties. Recently, interest in the search for new natural antioxidants has grown because ROS production and oxidative stress is linked to many chronic diseases. The usage of syn-thetic antioxidants generally leads to problems of tox-icity. In this study, we conclude that Flour-LOE and

Crust-LOE has a moderate antioxidant property

and could be attributed to the presence of phenolic and flavonoids compounds. The results of this study clearly showed that flour and crust could be of use as an easily accessible natural source of natural antioxi-dants and as a possible food supplement. Also, it could be used in ice cream as a source of flavour with com-placency. Overall evaluation of the results led to the conclusion that oleaster flour may be a suitable natural additive in ice cream formulation. Therefore, this study may provide base knowledge for future research. Acknowledgements

The authors would like to thank M. Cß ınar CßAKMAKCßI

for the original idea related oleaster (Ibrahim Hakkı Fen Lisesi student, Erzurum, Turkey).

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