Total lipid content in the seeds was 18.1–21.5% and 0.2–0.3% in the non-seed fraction. Punicic acid was the predominant fatty acid in the seed lipids and linoleic acid was the major fatty acid in the non-seed fraction. All the varieties had the same saturated/unsaturated fatty acids ratio of 0.1 for the seeds and 0.5 for non-seed tissues. Linoleic acid, palmitic acid, and oleic acid are most abundant in aril juice and peel and are secondary in abundance in seeds; however, punicic acid was not detected in the non-seed tissues. Pomegranate seed had a high content of α- and γ-tocopherol . The most abundant phytosterol was β-sitosterol, ranging from 32.7 to 345.8 mg/100 g. There were more phospholipids in seeds than in aril juice and peel. Phosphatidylcholine content varied from 5.8 to 23.1 mg/100 g and phosphatidylethanolamine ranged from 10.2 to 74.2 mg/100 g in all the seed varieties. Significant differences were found between the four cultivars in their different lipid components . Figure 3B illustrates a representative picture of the relative content of fatty acids in pomegranate non-seed fruit tissues . Anthocyanins are the key color molecules of pomegranate present in various parts of the pomegranate trees, growing raspberries in container including leaves, flowers, and fruits. The pomegranate fruit is a rich source of anthocyanins and produces several derivatives of anthocyanins.

These secondary metabolites accumulate in all fruit tissues and mainly in the edible part of the fruit, the arils, and in the fruit peel . Six anthocyanin molecules were identified in pomegranate fruit, including mono- and di-glucosides of cyanidin , delphinidin , and pelargonidin . All six anthocyanin pigments were detected in pomegranate cultivars from different geographical regions, which include Israeli, Turkish, Spanish, Californian, Tunisian, Italian, and Chinese pomegranates . However, differences in the relative amounts of anthocyanins were found, depending on variety, climatic, and cultural variables . Some unusual anthocyanin molecules were reported by Fischer et al. , who detected cyanidin pentoside in pomegranate peel and juice and cyanidin rutinoside and cyanidin pentosidehexoside in the juice. Zhao et al. reported that peonidin hexoside and myricetin hexoside were detected in the peel of a dark red Chinese cultivar. These findings suggest that the pigment profile of pomegranates may be much more diverse. The tree of the “white” phenotype pomegranate varieties, which do not produce any anthocyanin , is vigorous and fertile. It seems, however, that the white flowers and anthocyanin-less fruits are more susceptible to browning and radiation damages . The accumulation of anthocyanin in young pomegranate leaves also suggests that it acts to protect the tissues from abiotic and biotic stresses during leaf development.While most Israeli and Mediterranean cultivars displayed negligible levels of delphinidines in their skins, delphinidins, and cyanidins were the major anthocyanins in their aril juice .

In Israeli cultivars delphinidine derivative content could reach about 40% of the total anthocyanin content of the aril juice and cyanidines could reach about 60% of the total anthocyanins in the aril juice. Similar data was also reported for “Mollar” in Spain, where delphinidine derivatives constituted about 50% and cyanidine constituted about 45% of the aril juice anthocynins . Juices from fruits of 30 varieties grown in Tunisia were studied for their anthocyanin content. The total anthocyanin content was different among varieties and ranged from 9 to 115 mg/L juice . Aligourchi et al. measured the amounts of total anthocyanins in the juice of 15 pomegranate varieties obtained from Yazd province in Iran. There was significant difference in total anthocyanin levels among varieties ranging from 15.0 to 252.2 mg/L juice. From these studies of different varieties originating from several regions in the world and from many others not reported here, it is evident that there are significant quantitative and qualitative differences in the anthocyanin content of peel and juice between pomegranate varieties. These differences can be attributed to the diverse genetic background of the fruits tested.The differences found in the composition and quantity of anthocyanin between the peel and the arils suggest that anthocyanin accumulation in these tissues reflects differential genetic control of anthocyanin production. This assumption is further supported by the different dynamics of anthocyanin accumulation in the peel and arils during fruit development . This tissue- specific differentialaccumulation of anthocyanins is one of the main difficulties in determining the ripening time of pomegranate fruit by external phenotypic parameters.

One of the most interesting aspects of pomegranate color from academic and practical point of view is the influence of environmental conditions on color accumulation. It is well-known that pomegranate fruit color, like that of other anthocyanin-accumulating plants, such as grapes, red orange, and roses, is sensitive to high temperatures . When fruits of evergreen pomegranates that can produce all year round were tested in the Arava desert in Israel during winter and summer, it was found that the content of anthocyanin in the aril juice was inversely related to the sum of heat units accumulated during fruit ripening . Moreover, it was found that in addition to their effects on the content of anthocyanins, the change of season influenced the level and composition of the anthocyanin derivatives in the juice. Thus, cyanidine molecules accumulated in the hotterseason and delphinidin derivatives accumulated in the cooler season . It was also noticed that di-glycosidic derivatives mostly accumulated in the hot season, while mono-glycosidic derivatives were mostly accumulated during the cooler season, suggesting that di-glycosidic conjugates of anthocyanins are more stable in higher temperatures . The effect of temperature on anthocyanin accumulation was also demonstrated when the content of anthocyanin in 11 different cultivars grown in the Arava desert in Israel was compared to the content of anthocyanin of the same cultivars grown accumulation in aril juice and peel was suggested . Anthocyanin content in the arils and peel of pomegranate fruit is also sensitive to salt stress . When two different pomegranate cultivars were irrigated with saline water it was found that increased salinity had a positive influence on anthocyanin accumulation in the pomegranate fruit peel . The increase in anthocyanin accumulation corroborates the proposed function of anthocyanins in plant response to environmental stress conditions . The magnitude of the effect of increased salinity concentrations from 1 to 6 dSm−1 was about 4-fold of anthocyanin for the highly colorful “Wonderful,” and about 8-fold for the pale color “SP- 2.” These findings differ from those obtained for the anthocyanin in the arils , where salinity had an adverse effect on anthocyanin accumulation, especially in “Wonderful.” As for exposure to different temperatures, exposure to salinity affected the level of anthocyanin derivatives. At elevated salinity levels, “Wonderful” fruit peel accumulated purple delphinidins in addition to the major pigment types, cyanidins and pelargonidins, whereas in “SP-2” the proportion of the orange color pelargonidins increased. The significance of these data to the physiology of the fruit and trees is not yet understood. However, it showed that anthocyanin content is dynamic and depends on environmental conditions, water quality and the genetic background of the trees. This understanding is important for commercial perspectives, as it determines the choice of cultivars in different environmental conditions and geographical locations. It also influences the quality and suitability of the fruit for medical or nutritional consumption.The high variability in color of the skin and arils of pomegranate suggest a strong genetic control of anthocyanin production in pomegranate. Several expressed genes that are highly correlated with anthocyanin accumulation during fruit development were first identified by Ben-Simhon et al. . These genes were initially isolated on the basis of their homology to known genes involved in the production of flavonoids and anthocyanins. They included the structural genes: PgLDOX , PgDFR, and PgCHS and the regulatory genes: PgTTG1 , PgAN1 , and PgAn2 . Up until now the only genes from pomegranate for which a confirmed function in anthocyanin production was reported are the genes which encode for the enzyme leucoanthocyanidin oxidase PgLDOX and for the WD40 type of transcription factor PgTTG1 . The function of the pomegranate gene PgTTG1 was shown by complementing the TTG1 mutant of arabidopsis with the pomegranate PgTTG1 homolog . In this case, large plastic pots for plants the pgTTG1 function was demonstrated for both the ability to regulate anthocyanin production and for regulating trichome formation.

The function of PgLDOX was confirmed by identifying the site of the recessive mutation within its coding sequence located between positions 90–91 downstream of the ATG initiation codon. The mutation disrupts the gene in the anthocyanin-less pomegranate mutant. This mutation abolishes the expression of LDOX in all the pomegranate tissues and prevents the accumulation of anthocyanin . The clear linkage of the mutation to the inability to produce anthocyanins was accomplished by genetic mapping, using segregating F2 populations for a white phenotype mutant that does not produce anthocyanins in its fruit and leaf tissues . The identification of PgLDOX as the gene responsible for the anthocyanin-less pomegranate phenotype was supported by Zhang et al. , who showed that the anthocyanin-less mutant does not express the PgLDOX gene. These authors cloned several additional candidate genes from white and red pomegranate cultivars related to anthocyanin synthesis and studied their expression . Efficient and effective metabolite extraction methods are also a key to understanding the composition and content of hydrolyzable tannins of pomegranates and their different tissues.Pomegranates have traditionally been consumed for fresh aril juice; therefore, several studies focused on quantification of hydrolyzable tannins in this tissue. Aril juices of 12 commercial pomegranate varieties and 5 non-commercial varieties grown and harvested in different regions contained 139.7–473.4 mg/L of ellagic acid and 300–810 mg/L of total phenolic acids and hydrolyzable tannins . Ellagic acid levels in the aril juices of eight Iranian cultivars were evaluated and ranged from 7 to 160 mg/L. Interestingly, total tannins, ranging from 15 to 32 mg/100 g, showed an inverse correlation with ellagic acid concentrations in these cultivars . In recent years, industrial procedures have been established that press juice from whole pomegranate fruits. Therefore, the commercial pomegranate juices contain hydrolyzable tannins from aril juice as well as other parts of the fruit. For example, the commercial juices of “Wonderful” contained 1,500–1,900 mg/L of punicalagins, about 100-fold higher than those present in aril juice . Similarly, punicalagins were in the range of 31–607 mg/L in aril juices, and 156–1,169 mg/L in whole fruit juices of 10 Iranian pomegranate cultivars . However, the levels of punicalagins in the aril juices of some cultivars were particularly high, e.g., the punicalagin level in the aril juice of “JPGRT” was significantly higher than those in whole fruit juices of cultivars “PSY” , “VKT” , “MY” , “SRAB” , and “TML” . Four major hydrolyzable tannins, including punicalagins, punicalins, gallagic acid, and ellagic acid, were quantified from whole fruits and aril juices of 29 local and domesticated Israeli accessions . In addition to variations in the relative abundance of the four hydrolyzable tannins , the accessions analyzed were largely different in the concentrations of each hydrolyzable tannin in whole fruits and aril juices. Furthermore, the hydrolyzable tannins were a thousand fold less concentrated in aril juices than in whole fruits .In comparison with fruit peels and aril juices, hydrolyzable tannins are less abundant in seeds. Total tannins, including gallotannins, ellagic acid derivatives, and gallagyl tannins were 4,792–6,894 mg/L in fruit peels of six cultivars grown in the southern United States, which were 50- to 60-fold and over 100-fold higher than those in aril juices and seeds, respectively . Punicalagins, punicalins, gallic acid, and ellagic acid were quantified in fruit peels, aril juices, and seeds of five widely consumed pomegranate cultivars in China . Punicalagins were found in fruit peels in the range of 61.75– 125.23 mg/g dry weight. In all of the cultivars analyzed, fruit peels contained more punicalagins and punicalins than aril juices did, while these hydrolyzable tannins were not detected in seeds . Although hydrolyzable tannin composition and content cannot be directly compared among different studies due to the different extraction and quantification methods they employed, it can be concluded that hydrolyzable tannins vary in different pomegranate accessions grown in the same region, suggesting genetic contributions to hydrolyzable tannins. On the other hand, variations in hydrolyzable tannins were also observed for the same cultivar, such as “Wonderful,” when grown in multiple locations in the world. This phenomenon can be due to the many landraces of “Wonderful” and additionally suggests that climate and cultivation have an effect on hydrolyzable tannins.