Investigation of physical, chemical and microbiological quality of grape and mulberry leathers sold in Elazig (In Türkiye)

Investigação da qualidade física, química e microbiológica de couros de uva e amoreira vendidos em Elazig (na Turquia)

ABSTRACT:

The aim of this study is the determination some quality parameters of grape and mulberry pestils (leathers) sold in Elazig. For this purpose, a total of 45 fruit pestil samples, of which 23 were grape pestils and 22 were mulberry pestils, were analyzed for their physical properties, chemical properties, and microbiological characteristics. In grape and mulberry pestils, the average L^* (lightness/darkness) values were 42.72 and 44.81, a^* (redness) values were 10.29 and 9.07, and b^* (yellow) values were 20.90 and 20.90, respectively. In grape and mulberry fruit pestil samples, the thickness values were 1.62 and 1.34, pH values were 3.82 and 4.75, acidity values (as citric acid) were 0.63 and 0.22%, a_w values were 0.602 and 0.627, dry matter values were 68.78% and 72.99 %, ash values were 2.25% and 0.64%, insoluble ash values in 10% HCl were 0.20 and 0.29, and Brix values were 18.83 and 19.36, respectively. TMAB, coliform, Staphylococcus-Micrococcus, and yeast-mold counts were found to be 4.72 and 4.48, 1.30 and 1.89, 2.11 and 2.12, and 2.04 and 2.11 log₁₀ cfu/g, respectively, in all samples examined. In 14 of the samples (31.11%), the total number of mesophilic aerobic microorganisms was found to be >5 log₁₀ cfu/g. Escherichia coli and Salmonella spp. were not found in any of the samples. However, the samples were found to contain significant levels of yeast-mold. There was no difference between the groups in microbiological terms in statistical analysis (P > 0.05). According to the current study, there was no standard production and not enough hygiene rules were observed in the pestil production process in family businesses in Elazig. On the other hand, essential information was obtained on some physical, chemical and microbiological quality parameters of grape and blackberry pulps sold in markets and stores in Elazig.

Key words:
traditional product; grape; mulberry; fruit leather; quality parameters

RESUMO:

O objetivo deste estudo é a determinação de alguns parâmetros de qualidade de pestilos de uva e amoreira (couros) vendidos em Elazig. Para tanto, um total de 45 amostras de pestil de frutas, sendo 23 de uva e 22 de amoreira, foram analisadas quanto às suas propriedades físicas, químicas e microbiológicas. Em pestils de uva e amoreira, os valores médios de L^* (claridade/escuridão) foram 42.72 e 44.81, os valores de a^* (vermelhidão) foram 10.29 e 9.07, e os valores de b^* (amarelo) foram 20.90 e 20.90, respectivamente. Nas amostras de pestil de uva e amoreira, os valores de espessura foram 1.62 e 1.34, os valores de pH foram 3.82 e 4.75, os valores de acidez (como ácido cítrico) foram 0.63 e 0.22%, os valores de a_w foram 0,602 e 0.627, os valores de matéria seca foram 68.78% e 72.99%, os valores de cinzas foram 2.25% e 0.64%, os valores de cinzas insolúveis em HCl a 10% foram 0.20 e 0.29, e os valores Brix foram 18.83 e 19.36, respectivamente. As contagens de TMAB, coliformes, Staphylococcus-Micrococcus e fungos de levedura foram 4.72 e 4.48, 1.30 e 1.89, 2.11 e 2.12 e 2.04 e 2.11 log₁₀ ufc/g, respectivamente, em todas as amostras examinadas. Em 14 das amostras (31.11%), o número total de microrganismos aeróbios mesófilos foi >5 log₁₀ ufc/g. Escherichia coli e Salmonella spp. não foram encontrados em nenhuma das amostras. No entanto, verificou-se que as amostras continham níveis significativos de bolor de levedura. Não houve diferença entre os grupos em termos microbiológicos na análise estatística (P > 0,05). De acordo com o estudo atual, não houve produção padrão e não foram observadas regras de higiene suficientes no processo de produção de pestil em empresas familiares em Elazig. Por outro lado, foram obtidas informações essenciais sobre alguns parâmetros físicos, químicos e microbiológicos de qualidade das polpas de uva e amora-preta comercializadas em mercados e lojas de Elazig.

Palavras-chave:
produto tradicional; uva; amora; couro de frutas; parâmetros de qualidade

INTRODUCTION:

To date, the interest in natural food products that are nutritious and healthy is increasing day by day (VISWANATH et al., 2018). This inclination has led the industry to introduce traditional products and new foods (YILDIZ, 2013; VISWANATH et al., 2018). Our country has a wide range of traditional food production techniques, and the use of fruits and vegetables obtained via traditional production has an important place among them (NAS, 1993).

Made from various fruits such as grapes, mulberries, and apricots, pestil is one of our traditional foods, which is usually prepared to be eaten in winter and has a high nutritive value (YILDIZ & BOYRACI, 2020). Pestil has an increasing popularity and demand owing to its features such as durability, light-weightedness, easy packaging, and easy consumption. In addition, functional components, such as phenolic compounds and carotenoids, derived from the fruits they are produced from, make these products more attractive in terms of being an alternative snack that is widely produced and consumed by further improving the production conditions in the future. Increasing interest in fruit growing and developments in this field necessitate the processing of fruits into different products in terms of evaluation and added value. Drying fruits and processing them into pestil are options with significant potential for domestic use and export, especially for the functional food market. In this context, in addition to the studies on the functional characteristics of the products, production methods, preservation, and packaging, the product promotion should be emphasized (KARA & KUCUKONER, 2019).

Pestil is among the foods prepared by boiling and drying with the addition of additives, such as sugar and starch, to the fruit pulp (KARA & KUCUKONER, 2019; SUNA & OZKAN-KARABACAK, 2019). Pestil is also a food source rich in carbohydrates, energy, antioxidants, minerals, vitamins, and fiber. This product, which is important in terms of nutrition and sweetening, is also a viable alternative as a healthy snack (NAKILCIOGLU-TAS et al., 2018). (Figures 1, 2 e 3).

Figure 1
Spread of pestil (fruit leather) (NAS & GOKALP, 1993).

Figure 2
Pestil (fruit leather) (ULUSAL-BAYRAM, 2018).

Figure 3
Packaged pestil (fruit leather) (BATU et al., 2007).

Pestil is a natural product of various fruits widely produced in Anatolia, Armenia, Lebanon, Syria, Arabia, Iran, and USA. Pestil-like products are named as fruit leather, bastik (bas-tegh), and lavaşak and qamar al deen (SENGUL et al., 2010; TONTUL, 2019). Pestil is produced from various fruits such as apples, mulberries, plums, cranberries, banaNAS, strawberries, pineapples, oranges, cherries, pears, carobs, figs, kiwis, apricots, and peaches worldwide (SENGUL et al., 2010; YILDIZ, 2013; KARA & KUCUKONER, 2019; SENGUL et al., 2020). Pestil is produced in various geographic regions and using different substances such as sugar or starch and in different production stages (SENGUL et al., 2010; YILDIZ, 2013).

Many studies have so far been conducted on fruit pestils in our country. Detailed information on these studies is shown in table 1 and table 2.

Table 1
Physical quality parameters in studies on grape and mulberry leather in Türkiye.

Author(s)	City	Pestil Type	L*	a*	b*	Thickness (mm)
KARAOGLU et al. 2020	Malatya	Mulberry	20.99	5.88	2.29	0.92-1.2
YUKSEL ET AL. 2020	Gümüşhane	Mulberry	40.44- 44.36	7.21- 12.18	16.48- 29.37
SUNA & OZKAN-KARABACAK, 2019	Bursa	Mulberry	28.57- 35.42	4.44-8.15	11.15-19.06
OZALTIN et al. 2018	Manisa	Grape	27.25-48.87	2.94-22.42	4.01-34.80
NAKILCIOGLU-TAS et al.2018	İzmir	Mulberry	36.46-38.42	1.84-7.72	(-1.55)-1.75	0.91-1.02
ULUSAL-BAYRAM, 2018	Gümüşhane	Mulberry	37.11-46.61	7.10-12.10	12.25-25.28	0.6-1.11
BALTACI & AKSIT, 2016	Trabzon-Gümüşhane	Mulberry
BALTACI et al. 2016	Gümüşhane		44.75-26.99	7.37-11.40	14.48-23.11
BOZ et al. 2016	Erzurum	Mulberry	31.64-35.86	5.33-9.41	0.63-8.55
KAMILOGLU & CAPANOGLU, 2014		Grape, mulberry, apricot, plum
YILDIZ, 2013	Gümüşhane	Mulberry	35.85-38.54	3.56-6.23	5.75-9.58
KESER et al. 2013	Elazığ	Grape
CANDEMIR et al. 2013	Ege Bölgesi	Grape
BOZ, 2012	Erzurum	Mulberry, Grape
KALKISIM, 2012	Gümüşhane	Mulberry
KARTAL, 2011	Erzincan, Mersin, Nevşehir, Tarsus	Grape, strawberry, apricot, peach, apple
SENGUL et al. 2010	Erzurum	Mulberry, apricot, Cranberry	39.37-41.35	3.92-7.63	15.56-18.22
TOKBAS, 2009		Mulberry
YILDIZ, 2009	Gümüşhane
ERCISLI & ORHAN, 2008	Çoruh Vadisi, Uzundere	Mulberry	14.79-17.47	9.18-14.99	2.43-4.21
CAGINDI & OTLES, 2005	İzmir	Grape, mulberry, apricot	57.87-101.64	(-2.20)-12.85	(-6.33)-22.90
KAYA & KAHYAOĞLU, 2005	Gaziantep	Grape
KAYA & MASKAN, 2003	Gaziantep
KAYA et al. 2002		Grape
MASKAN et al. 2002a	Gaziantep	Grape
MASKAN et al. 2002b	Gaziantep	Grape
NAS & GOKALP, 1993		Grape
EKSI & ARTIK, 1984		Grape, mulberry

Table 2
Chemical quality parameters in studies on grape and mulberry leather in Türkiye.

Author(s)	City	Pestil Type	pH	Acidity (%)	aw	Dry Matter	Ash	Brix (°Bx )
KARAOGLU et al. 2020	Malatya	Mulberry	5,67
YUKSEL et al. 2020	Gümüşhane	Mulberry		0.15-0.22	0.56-0.72		0.83-1.62	28.9-30.75
SUNA & OZKAN-KARABACAK, 2019	Bursa	Mulberry
OZALTIN et al. 2018	Manisa	Grape
NAKILCIOGLU-TAS et al. 2018	İzmir	Mulberry	6.19-6.88	2.49-3.76		87,71-89,04	1,73-1,84	18,83-34,01
ULUSAL-BAYRAM, 2018	Gümüşhane	Mulberry	4.5-5.71	0.16-5.8		84.88-88.03	0.35-0.75
BALTACI & AKSIT, 2016	Trabzon-Gümüşhane	Mulberry
BALTACI et al. 2016	Gümüşhane
BOZ et al. 2016	Erzurum	Mulberry	5.70-5.89	0.29-0.59				70.00-76.21
KAMILOGLU & CAPANOGLU, 2014		Grape, mulberry, apricot, plum
YILDIZ, 2013	Gümüşhane	Mulberry		0.14-0.15		89.25 -90.22	0.7-1.2
KESER et al. 2013	Elazığ	Grape
CANDEMIR et al. 2013	Ege Bölgesi	Grape
BOZ, 2012	Erzurum	Mulberry, Grape
KALKISIM, 2012	Gümüşhane	Mulberry				85.4	1.4
KARTAL, 2011	Erzincan, Mersin, Nevşehir, Tarsus	Grape, strawberry, apricot, peach, apple
SENGUL et al. 2010	Erzurum	Mulberry, apricot, Cranberry	3.73-5.72	0.07-0.41		85.57-87.54	0.18-1.27
TOKBAS, 2009		Mulberry				68,5
YILDIZ, 2009	Gümüşhane			0.12		80.31	0.62
ERCISLI & ORHAN, 2008	Çoruh Vadisi, Uzundere	Mulberry	3.43-3.66					14.30-19.35
CAGINDI & OTLES, 2005	İzmir	Grape, mulberry, apricot				83.7-88.20	0.2-2.0
KAYA & KAHYAOĞLU, 2005	Gaziantep	Grape			0.06-0.98			20
KAYA & MASKAN, 2003	Gaziantep					88,8
KAYA et al. 2002		Grape
MASKAN et al. 2002a	Gaziantep	Grape
MASKAN et al. 2002b	Gaziantep	Grape
NAS & GOKALP, 1993		Grape		0.2-6.2			1.4-3.5
EKSI & ARTIK, 1984		Grape, mulberry		0.2-0.7		85.7-88.7	1.40-1.60

Although there are many studies on the pestils of different fruits produced in our country in literature, the study on Elazig pestil is quite limited. This study was performed to determine the physical, chemical, and microbiological quality of grape and mulberry pestils sold at different sales points in Elazig.

MATERIALS AND METHODS:

Material

In this study, pestil samples were obtained from grocery stores, shops, and neighborhood markets in Elazig province. The samples were collected between June 2021 and September 2021, and a total of 45 samples (23 grape pestils and 22 mulberry pestils) (one sample per pack, in a clear bag, date of manufacture: 2021) were examined. The samples were duly placed in sterile bags in at least 500 g amount and brought to the Food Hygiene and Technology Laboratory of the Faculty of Veterinary Medicine and stored at 4±1 °C until they were analyzed.

Method

Physical analyses

The color values of the samples were determined according to the method specified by the CIElab system (CHN Spec, CS 10, China) and Pathare et al. (2012). The color area L^*, a^*, b^* was obtained from the average of four repetitions. The resulting L^* value referred to lightness/darkness, a^* value to red, and b^* value to yellow. The pestils were measured from at least four different points, and arithmetic averages of the measurement results were taken and evaluated.

Thickness measurements of the pestils were determined according to TS 9776 using a digital caliper (Loyka 5110-150 (IP54), China). The measurements were made from at least 10 different points in the pestils, and arithmetic averages of the measurement results were taken and evaluated (TSE, 2000).

Chemical analyses

The pH values of the samples were measured using a pH meter (HI 11310, Hanna Instruments, USA) calibrated using pH 4 and 7 buffer solutions. Total acidity was detected using the alkaline titration method in citric acid (SSA) (AOAC, 2010). Total dry matter, total ash, and insoluble ash in 10% HCI was determined according to TS 9776 (TSE, 2000). The value of the water activity of the pestils (a_w) was determined using the water activity analyzer (Testo-650, Germany) (LANG & STERNBERG, 1998). Water-soluble dry matter (Brix) was determined using a hand refractometer (FG 103/113) (TSE, 2000).

Microbiological analyses

For microbiological analyses, 10 g of pestil sample was taken into a sterile stomacher bag, and 90 mL of sterile 0.1% peptone water (Acumedia 7365A, UK) was added and homogenized in a shredder (BagMikser 400, France). Thus, a 10^-1 (¹/₁₀) dilution of the sample was prepared. Other dilutions, for example, were prepared from this dilution on the condition that the same diluent was used and were planted in two series using 1 mL each. Petri dishes containing 30-300 colonies were evaluated at the end of the incubation period (HARRIGAN, 1998).

Plate count agar (Merck 1.05463, Darmstadt/Germany) (24-48 hours at 35±1 °C) (USDA, 2011) for TMAB census, violet red bile agar (Merck 1.01406, Darmstadt/Germany) (24 hours at 37 °C) (ISO 4831, 2006) for coliform group bacterial counting, tryptone bile X-glucuronide agar (Merck 1.16122, Darmstadt/Germany) for Escherichia coli enumeration (4 hours at 30 °C first and then 18 hours at 44 °C) (ISO 16649-2:2001(en)), and Baird Parker agar (Merck 1.05406, Darmstadt/Germany) (30 hours at 36 °C) with added Egg Yolk Tellurite Emulsion (HiMedia FD046, India) for counting Staphylococcus-Micrococcus microorganisms (ISO 6888-1:2021(ISO 6888-1:2021(en)) were used. ISO 6579 (ISO, 2017) procedure was followed for Salmonella spp. analysis. Dichloran rose-bengal chloramphenicol agar (DRBC) (LAB 217, UK) (5 days at 25±1 °C) was used for yeast-mold counting (ISO 21527, 2008).

Statistical analyses

All data were analyzed in this study by SPSS 22 (IBM SPSS, IBM Corporation, USA) package program (COLLINS et al., 2009). The pestil samples were subjected to the independent samples t-test after the normality test, and the results were expressed as mean ± standard deviation. All data were evaluated at P ≤ 0.05.

RESULTS:

Physical findings

The color and thickness values of the pestils are shown in table 3. The color values of the pestils were measured from four different regions of the pestils, and their averages were taken and expressed as L^*, a^*, b^*. There were no in-group differences in color and thickness analyses, but only b^* (yellowness/blueness) color value differences were detected between the groups (P < 0.05) (P = 0.001).

Table 3
Physical analysis findings of the pestil samples (mean±standard deviation).

Properties	Pestil Type
		Grape			Mulberry
	Min	Max	Mean±Std.Dev	Min	Max	Mean±Std.Dev
L* (lightness)	23.47	55.89	42.72±9.14a	22.82	54.2	44.81±8.78a
a* (redness/greenness)	-3.45	27.29	10.29±6.63a	2.21	26.96	9.07±6.59a
b*(yellowness/blueness)	1.11	37.3	20.90±10.59a	15.36	52.69	20.90±10.43b
Thickness (mm)	0.61	5.762	1.62±1.39a	0.55a	2.21	1.34±0.58a

• a, b:Different lowercase letters are significantly different by the t-test (P < 0.05); Mean±Std.dev: Mean±Standard deviation.

Chemical findings

Statistical differences between the groups were determined as significant in all chemical parameter values, except water activity (a_w) and the amount of insoluble ash in 10% HCI. The results of the analyses of the chemical properties of the pestil samples are shown in table 4.

Table 4
Chemical analysis findings of grape and mulberry pulp (mean±standard deviation).

Properties	Pestil Type
	-------------------------Grape-------------------------			-----------------------Mulberry----------------------
	Min	Max	Mean±Std.Dev	Min	Max	Mean±Std.Dev
pH	2.1	6	3.82±0.99a	2.63	6.13	4.75±1.01b
Acidity (citric acid%)	0.05	1.05	0.63±0.30a	0.03	1.41	0.22±0.32b
Water activity (aw)	0.405	0.745	0.602±0.92a	0.433	0.758	0.627±0.09a
Dry Matter	62.38	80.36	68.78±4.98a	64.97	78.23	72.99±4.00b
Ash	0.51	10.62	2.25±2.82a	0.07	1.91	0.64±0.65b
Insoluble ash values in 10% HCI	0	1.15	0.20±0.29a	0	2.28	0.29±0.60a
Brix	12	29	18.83±6.29a	6	26	19.36±5.41b

• a, b: Different lowercase letters are significantly different by the t-test (P < 0.05); Mean±Std.dev:Mean±Standard deviation.

Microbiological findings

TMAB, coliform, Escherichia coli, Staphylococcus-Micrococcus, Salmonella spp., and yeast-mold values of the pestil samples are given in table 5 and table 6.

Table 5
Microbiological analysis findings of grape and mulberry pulp (mean±standard deviation)(log₁₀cfu/g).

Properties	-------------------------------------------------Pestil Type---------------------------------------------
	-------------------------Grape--------------------			---------------------Mulberry------------------
	Min	Max	Mean±Std.Dev	Min	Max	Mean±Std.Dev
Total Mesophile Aerobic Bacteria (TMAB)	3.00	5.95	4.72±0.74	3.24	5.94	4.48±0.62
Coliform	0.00	1.3	1.30±0.00	0.00	2.3	1.89±0.58
E.coli	0.00	0.00	0.00	0.00	0.00	0.00
Staphylococcus-Micrococcus	0.00	3.64	2.11±0.56	0.00	2.76	2.12±0.45
Salmonella spp.	0.00	0.00	0.00	0.00	0.00	0.00
Yeast-mold	0.00	3.95	2.04±0.94	0.00	2.5	2.11±0.46

Table 6
Distribution of general and specific microorganisms in grape and mulberry pestil samples.

Microorganism	---------------------------------------------------------log10 cfu/g--------------------------------------------------------
	< 1.0		1.0-1.99		2.0-2.99		3.0-3.99		4.0-4.99		5.0-5.99
	n	%	n	%	n	%	n	%	n	%	n	%
TMAB	-	-	-	-	-	-	7	15.56	24	53.33	14	31.11
Coliform	-	-	2	4.44	1	2.22	-	-	-	-	-	-
E.coli	-	-	-	-	-	-	-	-	-	-	-	-
Staphylococcus-Micrococcus	4	8.89	13	28.89	27	60	1	2.22	-	-	-	-
Salmonella	-	-	-	-	-	-	-	-	-	-	-	-
Yeast- mold	23	51.11	10	22.22	10	22.22	2	4.44	-	-	-	-

• n: Sample number; TMAB: Total Mesophilic Aerob Bacteria.

DISCUSSION:

Pestil is an important traditional food that is consumed popularly in Türkiye. This food can be produced in different ways from many fruits with a high export potential as a single or mixture by industrial (commercial) and regional methods.

Physical findings

Color

Color is one of the most important quality criteria that significantly affects consumer preferences in products such as fruit juice. The color of the juice is mainly attributed to the presence of various carotenoids, betalains, and anthocyanins, which are water-soluble diglycosides (MASKAN et al., 2002a; TIWARI et al., 2009). Browning reactions and water-soluble diglycosides that occur during the scalding process have a great effect on color formation in the pestil (MASKAN et al., 2002a). The color characteristics of the structural components are reflected in pestil samples. In grape samples, the lowest and highest L^* values were 23.47 and 55.89, a^* values were -3.45 and 27.29, and b^* values were 1.11 and 37.3. In mulberry samples, the lowest and highest L^* values were 22.82 and 54, a^* values were 2.21 and 26.96, and b^* values 15.36 and 52.69. In the statistical analyses, intra-group differences in color were not detected (P > 0.05). However, only b^* (yellowness/blueness) color value differences were found between grape and mulberry pestil groups (P < 0.05) (P = 0.001) (table 3). In this study, the differences in color values detected between the samples differed from those reported in other studies (table 1) because of the use of different fruit varieties in the production as well as the thickness differences resulting from the production.

Thickness

Another important physical parameter of a pestil is “thickness”. Although the thickness values of grape and mulberry pestils ranged from 0.61 to 5.76 mm and from 0.55 to 2.21 mm respectively. The differences in both pestil samples were not statistically significant (P > 0.05) (table 3). The thickness values were found to be between 0.6 and 4.58 in studies on pestils (table 1). It is considered that the differences obtained in this value (thickness) are due to different industrial or traditional production methods and flavors, such as hazelnut, pistachio, almond, and walnut, added to the pestil.

Chemical findings

In the samples examined, the pH value was determined to be between 2.1 and 6.0 and between 2.63 and 6.13, respectively, in grape and mulberry pestils. Statistical difference between the groups was found to be significant (P < 0.05) (table 4). According to the Turkish Standards Institute, the pH value should be in the range of 4.0-5.0 for grape pestil and 2.5-4.5 for mulberry pestil (TSE, 2000a; TSE, 2000b). The pH values of some pestil samples in our study were found to be above the values reported in the relevant standard. In the studies conducted by other researchers (table 2), the pH values were noted to be between 3.43 and 6.88. It is thought that the differences in the pH of the pestil mostly depend on the fruit pulp, fruit juice, components used in its formulation, and processing conditions such as heat treatment and drying techniques (TONTUL & TOPUZ, 2017).

Acidity values (as citric acid) were determined to be 0.63% and 0.22% respectively, in grape and mulberry samples (table 4). According to TSE, statistical differences between the samples were found to be significant considering that the acidity rate was no more than 1% in grape pestil and the acidity that should be present in mulberry pestils was 0.2% (P < 0.05). The resulting acidity values are of the relevant standard (TSE, 2000a; TSE, 2000b) and were determined to be in compliance with the reported values. In other studies on pestils, the acidity rates were found to be between 0.07 and 6.2. These differences are thought to depend on the type of fruit, the structural components used in pestil production, the addition of condiments, and the heat treatment applied.

In this study, the water activity value (a_w) was determined to be 0.602 and 0.627 in grape and mulberry samples, respectively (table 4). When the samples were evaluated statistically, it was determined that the difference between the groups was not significant (P > 0.05). In addition, according to formulation, drying conditions, and containment conditions, water activity has been reported to vary widely between 0.395 and 0.700 (PHIMPHARIAN et al., 2011; QUINTERO RUIZ et al., 2014; QUINTERO RUIZ et al., 2012; SEPULVEDA et al., 2000). In Türkiye, the water activity value (a_w) has been reported to be between 0.06 and 0.98 in studies on pestil (table 2). The differences between the studies may be related to the relative humidity of the storage site and packaging materials.

According to the Institute of Turkish Standards, the amount of moisture that should be present in the pestils is no more than 15% in grape and 18% in mulberry pestils (TSE, 2000a; TSE, 2000b). In our study, the amount of dry matter of pestils was found to be 68.78% in grape pestils and 72.99% in mulberry pestils, and the amount of dried substances of grape pestils was lower than the values given by TSE. Statistical difference between the groups was found to be significant (P < 0.05) (table 4). When the other pestil studies conducted in our country were examined, the dry matter amounts were found to be between 68.5 and 89.25. It is thought that the differences obtained may be due to the differences in drying type and drying time.

The ash content of the pestil samples increases with the increase in the number of structural additives (KARAOGLU et al., 2020). In this study, the ash amounts of the pestils were determined to be 2.25% in grape pestil and 0.64% in mulberry pestil. When evaluated in terms of differences between the groups, it was observed that there was a statistically significant difference (P < 0.05) (table 4). Considering that the amount of ash determined by TSE was 2.5% in grape pestils and 4% in mulberry pestils, all of the samples examined were in compliance with the value specified in the relevant standard (TSE, 2000a; TSE, 2000b). Statistical difference between the groups was found to be significant (P < 0.05).

Insoluble ash values in 10% HCI of the samples were determined to be 0.20% and 0.29%, respectively, for the grape and mulberry pestil samples. When the samples were evaluated statistically, it was determined that the difference between the groups was not significant (P > 0.05) (table 4). Considering that the amount of insoluble ash in 10% HCl is at most 0.1% according to TSE (2000), it can be said that the findings obtained in this study are considerably higher than the stated value. This difference can be attributed to the fact that it is not produced under hygienic conditions, that it contains a large amount of foreign substances, and that the soil used for its production is more in minerals, such as heavy elements.

Grape samples showed an average value of 18.83 ºBrix (ºBx, g/100g), whereas the average value in the mulberry pestils was 19.36 ºBriks (ºBx, g/100g). When the samples were evaluated statistically, it was determined that the difference between the groups was significant (P < 0.05) (table 4). When other studies on pestils were examined (table 2), it was determined that the Brix value was between 14.3 and 76.21.

Microbiological findings

Total mesophilic aerobic bacteria (TMAB) numbers in pestil samples were the lowest at 3 log₁₀ cfu/g and the highest at 5.95 log₁₀ cfu/g in grape pestil; the lowest value of 3.24 log₁₀ cfu/g and the highest value of 5.94 log₁₀ cfu/g were determined in mulberry pestil (table 5). When evaluated statistically, it was determined that the differences between the groups were not significant (P > 0.05). According to TSE (TS, 9776), the maximum number of TMAB should be 10⁵ cfu/g. Accordingly, 31.11% (14 samples) of the samples examined did not meet the relevant standard (table 6). In the study of ULUSAL-BAYRAM (2018), the TMAB count was determined to be 3×10² cfu/g on day 0, 5×10⁴ on day 90, and 2×10⁵ cfu/g on day 180 in unpackaged walnut fruit pestils and 3×10² on day 0, 3×10² at 3rd month, and 3.2×10³ at 6th month, 3.4×10³ at 9th month, 3.4×10³ at 12th month, and 3.4×10³ cfu/g at 15th month in packaged hazelnut pestils. The numbers of TMAB in plain, hazelnut, and walnut pestils collected from the field were determined to be 9.1×10⁴, 2.8×10⁵, 3.6×10⁵ cfu/g, respectively. The TMAB numbers of the pestils collected from the field were considerably higher than the numbers determined in our study. The different sample compositions and production processes caused differences in the total number of TMAB.

In our study, the number of coliform bacteria was determined at 1.30 log₁₀ cfu/g in grape pestil and 1.89 log₁₀cfu/g in mulberry pestil. When evaluated statistically, it was determined that the differences between the groups were not significant (P > 0.05) (table 5). In the ULUSAL-BAYRAM (2018) study, coliform microorganisms were not detected. In a study on the subject (ULUSAL-BAYRAM, 2018), the numbers of coliforms in plain, hazelnut, and walnut pestils collected from the field were determined to be 9.1×10⁴, 2.8×10⁵, and 3.6×10⁵ log₁₀ cfu/g. Differences in sample compositions and production processes and conditions in production and sales locations cause changes in the number of coliform bacteria.

The numbers of Escherichia coli and coliform bacteria are an indicator of the extent to which the hygiene and sanitation practices applied in the enterprise are implemented and applied. The presence of these bacteria in the product indicates that there is fecal contamination. The contamination can also be caused by the mixing of sewage water into the operating water, not paying attention to the personal hygiene of the personnel, and not complying with the hygiene rules at the sales points. E. coli bacteria were not detected in grape and mulberry pestil samples in our study (<1.0 log₁₀ cfu/g) (table 5 and table 6). Likewise, it was reported that E. coli bacteria could not be detected in the pestil samples examined in ULUSAL-BAYRAM (2018). The numbers of E. coli in plain, hazelnut, and walnut pestils collected from the field were determined to be 7.2×10¹, 1.2×10², and 1.4×10² log₁₀ cfu/g, respectively. Differences in sample compositions and production processes and conditions in production and sales locations may cause changes in the numbers of E. coli.

In samples collected from the market, Staphylococcus-Micrococcus count was the lowest at 0 log10 cfu/g and the highest at 3.64 log₁₀ cfu/g in grape pestil; the lowest count of 0 log₁₀ cfu/g and the highest count of 2.76 log₁₀ cfu/g were detected in mulberry pestil (table 5). When the samples were evaluated statistically, it was determined that the differences between the groups were not significant (P > 0.05). The standard mentioned in TSE (2000) states that Staphylococcus aureus should not be present. In terms of Staphylococcus-Micrococcus numbers, 45 examples (100%) were found not to meet the aforementioned standard (table 6). In the ULUSAL-BAYRAM (2018) study, Staphylococcus-Micrococcus microorganisms were not detected in pestils. ULUSAL-BAYRAM (2018) determined the number of Staphylococcus aureus in plain, hazelnut, and walnut pestils collected from the field to be 1×10¹, 1×10², and 1x10² cfu/g, respectively. The fact that the personal hygiene of the personnel working in the production and sales areas was not taken into account could have caused the changes in the numbers of Staphylococcus-Micrococcus.

Salmonella spp. was not detected in any of the samples examined in our study (<1.0 log₁₀ cfu/g) (table 5 and table 6). The pestil samples complied with the criteria specified in TSE. In the ULUSAL-BAYRAM (2018) study, Salmonella spp. microorganism was not detected. The result of this study is in line with the findings of our present study.

Total yeast-mold numbers in the market-provided fruit pestil were the lowest at 0 log₁₀ cfu/g and the highest at 3.95 log₁₀ cfu/g in grape pestil; the lowest value was 0 log₁₀ cfu/g and the highest value was 2.5 log₁₀ cfu/g in mulberry pestil. When the samples were evaluated statistically, it was determined that the differences between the groups in terms of yeast-mold number were not significant (P > 0.05) (table 5). The maximum number of yeast-mold specified in TSE (2000) is 10² cfu/g. Accordingly, it was determined that 26.67% (12 samples) of the samples examined did not comply with the relevant standard (table 6) (TSE, 2000). In the study of ULUSAL-BAYRAM (2018), the yeast-mold count was found to be 1×10² on day 0, 2×10³ on day 90, and 3×10⁴ on day 180 in unpackaged walnut fruit pestils, whereas it was 1×102 on day 0 and 1×10² at 3, 6, 9, 12, and 15 months in packaged hazelnut fruit pestils. ULUSAL-BAYRAM (2018) reported the numbers of yeast-mold in plain, hazelnut, and walnut pestils collected from the field to be 3.1×10⁴, 1.2×10⁴, and 2.3×10⁴ cfu/g, respectively. The type of drying technique used in production (cabinet drying, sun drying, etc.), the microbiological condition of the drying air, and the air of the facility where the production takes place affect the total yeast-mold amount. Keeping the products at room temperature in drying and storage rooms significantly increases the total amount of yeast- mold. The variety of fruits used in pestils, ecological conditions, ripening period, storage, processing dough, pestil preservation conditions, and analysis method can cause these differences (ULUSAL-BAYRAM, 2018).

CONCLUSION:

Based on the results of the current study, there was no standard production and not enough hygiene rules were observed in production process of grape and mulberry pulps sold in markets and shops in Elazig. It is due to the fact that pestils are mostly produced in family-type enterprises in Türkiye. In addition, it is challenging to undertake the hygiene rules in such enterprises. On the other hand, essential information was obtained about some physical, chemical, and microbiological quality parameters of grape and mulberry pulps sold in markets and shops in Elazig. Like HACCP, it will be beneficial for food safety and consumer (public) health to plan and implement food safety systems both at production sites and at sales points, not to sell the products in the open, and to sell them in appropriate packaging materials.

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• CR-2022-0234.R1

Edited by

Editors: Leandro Souza da Silva (0000-0002-1636-6643) Jesús Lozano Sánchez (0000-0001-8769-3070)

Publication Dates

• Publication in this collection
  23 Feb 2024
• Date of issue
  2024

History

• Received
  25 Apr 2023
• Accepted
  19 Sept 2023
• Reviewed
  18 Dec 2023