A review of nutritional value and putative health-effects of quince (Cydonia oblonga Mill.) fruit

Quince might be used in a several ways, many processed forms of this fruit gained worldwide popularity. Fruits can be processed into juices, jams and spirits. Persian physicians advised patients suffering from chronic recurrent headache to eat a quince before breakfast due to its apparent prophylactic effects (Gorji, 2003). Others suppose quince jam is benefi cent in gastrointestinal disorders. In many countries throughout Europe, Asia and Africa, quince is used as a component in traditional dishes.


Introduction
Quince might be used in a several ways, many processed forms of this fruit gained worldwide popularity. Fruits can be processed into juices, jams and spirits. Persian physicians advised patients suffering from chronic recurrent headache to eat a quince before breakfast due to its apparent prophylactic effects (Gorji, 2003). Others suppose quince jam is benefi cent in gastrointestinal disorders. In many countries throughout Europe, Asia and Africa, quince is used as a component in traditional dishes.

Nutritional composition
The nutritional composition of quince is compared with apple, a close relative of this fruit crop but consumed in great quantities. All data are expressed for 100 g fresh weight of whole fruits according to Bíró and Lindner (1999). Energy, protein, acid, carbohydrate, ash and fi bre contents in quinces are higher than those in apples, while quince fruit contains less water ( Table 1).
The contents of pectins in fruits ranged between 1.75 and 3.51 g/100 g FW, and cultivar 'Hruškovita' accumulated pectins in greatest amount (Rop et al., 2011). The quince pectin had a high galacturonic content (78%), and a degree of methoxylation of about 60% corresponding to a mediumhigh methoxyl pectin (Forni et al., 1994).
Vitamin C content of quince is nearly two-times higher than in apple (Bíró and Lindner, 1999) (Table 2), while other authors reported nearly identical quantities of ascorbic acid in quinces and apples (13 and 12 mg/100 g, respectively) (Souci et al., 2002). According to Bíró and Lindner (1999) apple contains more from most of the vitamins, while Souci et al. (2002) determined nearly identical amounts of vitamins in both fruit crops.
For Czech cultivars, the vitamin C contents in quince ranged from 50 to 80 mg/100 g intact fruit (fl esh and peel together). Fruits of the cultivar 'Muškatová' contained the highest amount, 79.31 ± 2.01 g/100 g FW of acorbic acid (Rop et al., 2011). This value is defi nitely higher than those specifi ed in Table 2 or compared with the USDA reference value of 15 mg (USDA, 2012), which confi rms that quince cultivars are characterized by a great genetic variability. It was also confi rmed by determining fruit antioxidant capacity and total polyphenolic contents in 12 commercial cultivars (Papp et al., in press). Quince is a richer source of mineral elements compared to apple. The summarized quantity of the measured mineral elements is almost two-times higher in quince than apples ( Table 3). The unique fragrance of quince fruit is attributable to the specifi c composition of its essential oil (Schreyen et al., 1979;Tsuneya et al., 1983) in which the characteristic compounds were thought to be monoterpenic lactones and oxides (Tsuneya et al., 1983). In the early nineties, Lutz et al. (1991) indicated the presence of monoterpenic glucosides in quince, which were supposed to be the putative precursors of the lactones and oxides.

Polyphenolic composition of quince fruit
Qualitative and quantitative analyses of phenolic compounds were carried out on quince fruit samples from seven different geographical origins in Portugal (Silva et al., 2002). Both fruit fl esh and peel were analyzed by reversed-phase high performance liquid chromatography (HPLC) coupled with diode array detector or mass spectrometry. Differences were noted between the phenolic profi les of fl esh and peel in all studied cases. The fl esh contained mainly caffeoylquinic acids (3-, 4-, and 5-O-caffeoylquinic acids and 3,5-dicaffeoylquinic acid) and rutin (quercetin 3-O-rutinoside). The peel presented the same caffeoylquinic acids and several fl avonol glycosides: quercetin 3-galactoside, kaempferol 3-glucoside, kaempferol 3-rutinoside, and several unidentifi ed compounds. The highest content of phenolics was found in peels.
In Tunisian quinces, total phenolic contents of the fl esh and peel parts ranged from 37 to 47 and 105 to 157 mg/100 g of fresh weight, respectively (Fattouch et al., 2007). Chlorogenic acid (5-O-caffeoylquinic acid) was the most abundant phenolic compound in fl esh (37%), whereas rutin was the main one in peel (36%).

Putative health-effects of quince consumption
Quince was reported to have antiulcerative effects (Hamauzu et al., 2006). However, the strongest antiulcerative effect was declared for Chinese quince (Pseudocydonia sinensis C. K. Schneid.) on ethanol-induced gastric ulcers in rats. Pre-administration of Chinese quince and quince phenolics suppressed the occurrence of gastric lesions in rats, whereas apple phenolics seemed to promote ulceration. The antioxidative property of rat blood increased in all rats fed by quince phenolics. Ferulic acid and isoferulic acid were detected as major metabolites in rats consuming nd: non-detected apple phenolics, quince phenolics, and 5-caffeoylquinic acid standard. (-)-Epicatechin and its 3'-O-methyl ether were detected in rats administered apple phenolics and (-)-epicatechin standard. The results showed that Chinese quince and quince phenolics might have health benefi ts by acting both in blood vessels and on the gastrointestinal tract. Chronic infl ammation is a hallmark of several diseases including diabetic complications, rheumatoid arthritis, infl ammatory bowel disease, atherosclerosis and cancer. Essafi -Benkhadir et al. (2012) reported the anti-infl ammatory effect of a polyphenolic extract from Tunisian quince. Lipopolysaccharide (LPS) treatment of human THP-1derived macrophages induced the secretion of high levels of the pro-infl ammatory cytokine TNF-and IL-8, which was inhibited by quince peel polyphenolic extract in a dosedependent manner. Quince polyphenols also enhanced the level of the anti-infl ammatory cytokine IL-10 secreted by LPS-treated macrophages. Quince polyphenols inhibited the LPS-mediated activation of three major cellular proinfl ammatory effectors (nuclear factor-kappa B, p38MAPK and Akt). These data indicate that quince peel polyphenolic extract induces a potent anti-infl ammatory effect and that a quince-rich diet may help to prevent and improve the treatment of infl ammation-associated diseases. Shinomiya et al. (2009) examined the effect of a crude hot-water extract (HW) of quince fruit on type I allergy in vivo and in vitro. The oral administration of the quince HWadded diet to NC/Nga mice (NC/Nga mice are known to exhibit spontaneous development of dermatitis) for 63 days showed a signifi cant decrease in the development of atopic dermatitis-like skin lesions under conventional conditions. The concentration of IgE in the serum collected from mice fed with quince HW was lowered in a dose-dependent manner. Moreover, quince HW inhibited the release of betahexosaminidase from rat basophilic leukaemia cells after a 24-hour treatment. The quince HW fraction of less than 3 kDa reduced the mRNA expression of the high-affi nity IgE receptor (Fc RI) subunit. These results suggest that quince HW had an inhibitory effect on type I allergy by suppressing IgE production and IgE-mediated degranulation.
Alesiani et al. (2010) identifi ed several compounds with antiproliferative effects from quince peels although Carvalho et al. (2010) could not show inhibitory effects of quince fruit fl esh and peel on human kidney and colon cancer cells. However, the extracts from leaf showed concentration-dependent growth inhibitory activity toward human colon cancer cells, while no effect was observed in renal adenocarcinoma. Seed extracts exhibited no effect on colon cancer cell growth, whereas strong antiproliferative effi ciency was observed against renal cancer cells for the highest concentration tested (500 μg/mL).
The antimicrobial activity of quince extracts against different microorganism strains was investigated by Fattouch et al. (2007). Quince peel extract was the most active for inhibiting bacterial growth. It seems that chlorogenic acid acts in synergism with other components of the extracts to exhibit total antimicrobial activities. Thirty-four polyphenols were detected by Karar et al. (2013), nine of which were not reported previously in quince. The crude extract of quince fruit polyphenols showed antibacterial activity against the Gram-negative bacterium Escherichia coli. Five polyphenols, 5-O-caffeoylquinic acid, quinic acid, quinic acid derivative, proanthocyanin B1 and methyl 5-O-caffeoylquinate were isolated and tested for their antibacterial activity. Quinic acid and a quinic acid derivative showed strong inhibition against E. coli.
An interesting study was published on the comparison of the phenolic profi le and antioxidant potential of quince leaf and green tea (Camellia sinensis) (Costa et al., 2009). Quince leaf exhibited a signifi cantly higher reducing power than green tea (mean value of 227.8 ± 34.9 and 112.5 ± 1.5 g/kg dry leaf, respectively). Quince leaf extracts showed similar 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activities but signifi cantly lower than that presented by green tea extract. Under the oxidative action of 2,2'-azobis(2amidinopropane) dihydrochloride, quince leaf methanolic extract signifi cantly protected the erythrocyte membrane from hemolysis in a similar manner to that found for green tea. These results point to the fact that quince leaf may be applied as a preventive or therapeutic agent in diseases associated with free radical damage.
In conclusion, the review of the papers focused on quince phytochemical composition indicates a considerable extent of genetic variations among cultivars and also allowed to identify perspective therapeutic targets. Since polyphenolics are supposed to be responsible for the major part of benefi cial health-effects, this information might be exploited in designing future breeding programs for quince improvement and opening new ways for health-related uses including the development of quince-based functional foods.