Mean °Brix values ranged from 14.9 to 16.8 . Most cultivars had mean °Brix values that were similar to Wonderful. However, ‘Golden Globe’ had the least quantity of °Brix and this was significantly lower than ‘Wonderful.’ Golden Globe had significantly less °Brix than most other cultivars. °Brix typically increased from one month to the next, regardless of cultivar . There were some very weak correlations between °Brix and other parameters, but they were not notable. There were no differences between years for °Brix when data was pooled to evaluate effect of year on these traits. There were large differences among cultivars for TA . Haku Botan had the highest TA and Ambrosia, Eversweet, Golden Globe, Green Globe, and Loffani had the lowest TA, with all of these cultivars being significantly different than Wonderful. ‘Wonderful’ had a mean TA of 1.60, which was similar to the TA of ‘Desertnyi’ and ‘Parfianka.’ The only other cultivars that had a higher TA than Wonderful other than Haku Botan was Phoenicia. Mean values for TA tended to decrease over time . There were no differences between years for TA when data was pooled to evaluate effect of year on these traits. There were stark differences among cultivars for sugar to acid ratio, the MI utilized in this study . Wonderful had a relatively low MI compared to many of the other cultivars. Cultivars with similar MI compared to Wonderful include Desertnyi, Parfianka, and Phoenicia. Cultivars with very high MI include Eversweet, Golden Globeand Loffani.
The cultivar with the lowest MI was Haku Botan,plastic flower pots with less than half of the MI of Wonderful. Mean values for MI tended to increase from one month to the next . There was a difference between years for MI when data was pooled to evaluate effect of year on these traits, with 2015 having greater MI than 2014 with 2015 and 2014 having 25.1 and 20.5 MI units, respectively . At maturity, pomegranate fruit are typically 3.5 to 6.5 cm in diameter with a weight of 30 g to several hundred grams , although commercially-valuable fresh market fruit typically weigh more than 400 g and the largest sized ‘Wonderful’ fruit from mature trees can have a diameter of over 10 cm. The cultivars that meet these fruit weight specifications include Golden Globe, Green Globe, Loffani, Parfianka, Phoenicia and Wonderful. Although it is important to note that the sweet, low acid of cultivars such as Ambrosia and Eversweet and the less heavy soft-seeded cultivars Eversweet and Desertnyi could have market potential for these unique traits despite being less than 400 g on average. Values for mean fruit weight and diameter of ‘Wonderful’ in the present study were in agreement with Wetzstein et al. , who reported a mean fruit weight of 345 g and a mean fruit diameter of 90 mm for ‘Wonderful’ fruit obtained from commercial growers. The fruit weight, diameter and length data indicate that there are cultivars that do meet the industry specifications for weight and size and there is no effect of year on these traits . These cultivars should be investigated in cultivar trials to determine if these cultivars are productive enough for commercial growers. ‘Wonderful’ fruit have a problem with the lobes of the calyx breaking off from the fruit during harvest, packing, and transport, causing crown damage.
This loss of distinguishing morphology causes fruit to be less appealing and identifiable in the market, with the crown of the fruit being partially damaged to completely missing by the time consumers interact with the product. Crown damage is also an entry point for pathogens in the fruit during the food supply chain and should be minimized as much as possible . Information related to the calyx length and diameter of pomegranate fruit are virtually nonexistent in the literature and the data herein represent the first such data of its kind. Because there were differences in fruit calyx dimension among cultivars, it is important to determine if these differences will result in less crown damage to the fruit during harvest and in transport and storage. It is likely that shorter, wider calyxes will result in less damage to the fruit and post harvest studies should be conducted to determine if some cultivars have more durable calyxes than others, especially as it relates to the food supply chain. Such calyxes of different sizes might be less attractive to consumers; therefore, consumer desirability effects of calyx size should also be investigated.Mean values for weight of 100 arils for ‘Wonderful’ fruit are in agreement with Wetzstein et al. . Wetzstein et al. reported that each aril weighed 357 mg on average, and when multiplying that value by 100 arils, the weight of 100 arils for ‘Wonderful’ was reported to be 35.7 g, which is very close to the mean value for weight of 100 arils by the present study . Weight of all arils for ‘Wonderful’ was about 50 g higher in the present study than the mean value reported by Wetzstein et al. . These differences in weight of all arils could be because ‘Wonderful’ fruit in the present study consist of fruit harvested over three months and the fruit used in Wetzstein et al. were from closer harvest dates.
Aril weights did increase over time for all cultivars in both seasons. In terms of fruit edible fraction for ‘Wonderful,’ results were in close agreement with Wetzstein et al. , who reported that 50.4% of the fruit is edible and in the present study, we found that 48.8% of the fruit was edible. It is important to note that because there are differences in terms of individual and total aril weights in the fruit and fruit edible fraction, cultivars other than Wonderful might be more profitable for growers who are selling the fruit for packaged arils. If arils are packaged based on weight or volume, cultivars with fruit that have larger or more arils per fruit could end up being superior to Wonderful for this purpose. However, it is important to note that aril weight may be caused by seed weight or density, so consumer taste panels must be utilized to determine if the larger seed size influences consumer desirability. The mean values for °Brix were in agreement with Beaulieu et al. for ‘Haku Botan’ and ‘Wonderful,’ which were reported to have 15.90 and 17.43 °Brix, respectively. Although values were very similar for these two cultivars when compared to the present study, it is important to note that °Brix was higher in the present study when compared to values reported in Beaulieu et al. . Values for °Brix were similar to values reported in other studies involving pomegranate germplasm . Trends of °Brix fluxes over time are in agreement with the literature for pomegranate , with values for °Brix increasing from one month to the next. °Brix values were at quantities generally suitable for consumption, but Golden Globe had lower °Brix compared to most other cultivars, but because this mean value was over 15, it should be suitable for consumers , especially because of its low acidity. Upon visual observation, the arils for ‘Golden Globe’ seemed to have a pitting trait that may represent an unknown pathology. All other cultivars were similar to Wonderful for °Brix and did not show the pitting seen in Golden Globe. There was no year effect on °Brix ,plastic garden container which is important to consider for commercial grow operations. The mean values for TA were largely in agreement with Beaulieu et al. for ‘Haku Botan’ and ‘Wonderful,’ which were reported to have 2.05 and 1.32% TA, respectively. However, values for TA for ‘Haku Botan’ were lower and TA values for ‘Wonderful’ were higher in the present study. Mean values for TA are in agreement with TA values reported in other pomegranate germplasm studies . Because TA is the primary factor in pomegranate flavor , it is important to note that there are pomegranates with TA much lower than what is typical in the market and these pomegranates should be evaluated for consumer desirability, especially those with softer seeds because they have the potential to be accepted by consumers as reported by Stover and Mercure .
Trends of TA fluxes over time agree with other literature for pomegranate , with values for TA decreasing from one month to the next. It is likely that harvest date will be greatly determined by TA, especially in groves with cooler climates. Values for TA were rather high for ‘Wonderful’ and ‘Phoenicia’ in September, so it makes sense that harvest dates for ‘Wonderful’ are typically in mid- to late-October. Other cultivars with low acid may be able to be harvested in September as long as the external and internal components of the fruits color up by that harvest date.The values for MI were typical of pomegranates and demonstrate the diversity of pomegranate germplasm in the United States. Cultivars with high MI have fruit that are low acid and thus taste sweeter at maturity. Pomegranate cultivars with low MI close to 5 have fruit that are sour at maturity. Values for MI increased over time and this is in agreement with Fawole and Opara . Many sweet cultivars were at the 8.1 MI that is described in the literature in mid-September, but the fruit were not mature, i.e. they lacked external and interior color. Because MI values for sweet fruit are higher than Wonderful on average, it is important to develop other criteria for maturity for these cultivars. For example, it may be possible to determine fruit maturity by a set of indices, including external and internal fruit color, aril weight and °Brix. It is important to emphasize that there were no differences detected among cultivars for AA. This is important because often the industry standard is marketed to be the only cultivar known to have powerful antioxidant activity in America. The results indicate that, for California-grown cultivars evaluated for fruit quality in this study, AA is the same regardless of cultivar for a given harvest date. Because all cultivars utilized in this research had the same antioxidant activity, this opens the door to the adoption of new cultivars by growers if AA was a limiting factor in diversifying the market. With more studies, it will be possible to determine if early cultivars have higher antioxidant activity than the late season ‘Wonderful,’ which could serve as a marketing point for industry hoping to compete with the major players in the market. The values for AA are in agreement with other studies on the AA of pomegranate juice using the DPPH inhibition method . Mean values of AA decreased over time, which is typical for pomegranate . It is unlikely that AA will play a role as a potential maturity index as all cultivars had the same AA, despite large phenotypic differences for other fruit quality traits among cultivars. It is important to note that there is no correlation between antioxidant activity and health benefits in humans. Values reported herein for TP agree with other studies , especially for ‘Wonderful’ . Mean values for TP did not seem to follow a generalized trend over time, which is different from most other fruit quality traits. Cultivars that had similar quantities of TP were Golden Globe, Green Globe, Haku Botan, Loffani, and Phoenicia. It is unlikely that TP will be a reliable trait to be used as a maturity index. However, it may be possible that certain classes of phenolics could be an indicator of a fruit’s maturity or development, but identification of individual phenolic compounds is beyond the scope of this study.We evaluated fruit and juice quality traits of ten pomegranate cultivars in the NCGR germplasm by comparing commercial traits to the industry standard, Wonderful, and found that there are other cultivars that meet important market specifications. We also determined that some fruit quality traits may be more useful than others as maturity indices for determining fruit maturity and potential harvest windows. Results indicated that there exists great phenotypic diversity in the USDA NCGR pomegranate germplasm collection. Further research is needed to determine suitability for growers by means of field trials and consumer taste panels should be conducted to determine consumer preferences of potential commercial cultivars.