# Does Organic Farming Increase Raspberry Quality, Aroma and Beneficial Bacterial Biodiversity?
## 4 Discussion
### Quality Parameters of Organic and IPM Raspberry Fruits  
Several studies report the influence of the cultivation method on the quality of fruits and berries [64; 65; 66]. As raspberry is a highly perishable product, the identification of the optimal maturity stage is crucial for fruit quality at consumption. Visual assessment of fruit colour or ease of fruit detachment from the receptacle are the parameters mostly used in raspberry industry to determine harvesting time. In this work, organic and IPM fruits were harvested at the same levels of detachment force, but they differed for several qualitative parameters (Figure 3). IPM fruits were characterized by higher weight and titratable acidity, whereas organic ones contained more anthocyanins. During the raspberry maturation process, acidity shows a steady increase in the early stages, followed by a substantial decrease during ripening. Anthocyanidins content and fruit weight increase during maturation. Finally, variations in soluble solid content are negligible at the maturation stages close to harvest (i.e., physiological maturity) [4]. Therefore, the differences observed in the quality parameters may be related to a more advanced ripening of organic berries than IPM ones, in spite of similar detachment forces. Exogenous IAA application on berries has been observed to stimulate ethylene emission, thus promoting fruit ripening [67]. IAA-producing bacteria, such as _P. agglomerans_ and _T. terrea_, could be isolated only from organic fruit (Table 2). In this view, the difference in maturation could be related to the bacteria residing on the fruit, or on the fruitful during development. An increase in ethylene production and respiration rate has been detected from the white fruit stage until full maturity [67; 68] and induction of anthocyanin formation was promoted after ethylene application [69]. We suggest that the promotion of maturation by IAA producing bacteria exceeded the negative effect of auxin on anthocyanin content. In fact, IAA has been reported to have a negative correlation with anthocyanin contents indicating that anthocyanin accumulation starts when IAA content decreases [70]. Moreover, in raspberry, exogenous application of a high concentration of IAA (100 \(\upmu\)M) at fruit with equal ripening stage was found to depress anthocyanins accumulation [71]. However, previous studies highlighted that organic cultivation promote anthocyanin content in berries [64; 66; 72; 73]. Thus, other factors may have contributed to the increase of anthocyanin. It is generally assumed that organic plants contain more secondary metabolites, as a form of protection against the stress factors remediable in IPM crops by cultural inputs, i.e., fertilizers and pesticides [74]. In horticultural plants, an increase of total nitrogen generally depresses anthocyanin accumulation [75; 76]. However, in strawberry cell culture, the percentage of NH4\({}^{+}\) in the total nitrogen concentration directly correlated with changes in cell density and anthocyanin content [77]. Similarly, in purple basil, NH4\({}^{+}\) availability positively correlated with the contents of anthocyanins [78]. All the bacterial species uniquely isolated in organic fruit can produce NH4\({}^{+}\). Thus, the higher availability of this cation in fruits might have increased anthocyanin in organically produced berries. Fruit acidity is an important component of organoleptic quality [79] and in berries it is influenced by several environmental and plant factors (i.e., plant age and genotype, temperature, harvest season and orchard location) [21]. In previous studies on raspberry 'Tulameen' and 'Kweli', higher tittatable acidity values were found in organic raspberries versus IPM grown ones [73]. Contrastingly, our results highlighted lower acidity values in organic fruits. Several studies suggest a role of bacteria on fruit acidity. _Bacillus_ sp. inoculated on flowers and leaves of sour cherry affected sugar content and tittatable acidity of fruits [80].