Cherimoya (Annona cherimola Mill.) fruit is an attractive candidate for food processing applications as fresh cut. However, along with its desirable delicate taste, cherimoya shows a marked susceptibility to browning. This condition is mainly attributed to polyphenol oxidase activity (PPO). A general lack of knowledge regarding PPO and its role in the oxidative loss of quality in processed cherimoya fruit requires a better understanding of the mechanisms involved. The work carried out included the cloning of a full-length cDNA, an analysis of its properties in the deduced amino sequence, and linkage of its mRNA levels with enzyme activity in mature and ripe fruits after wounding. The results showed one gene different at the nucleotide level when compared with previously reported genes, but a well-conserved protein, either in functional and in structural terms. Cherimoya PPO gene (Ac-ppo, GenBank DQ990911) showed to be present apparently in one copy of the genome, and its transcripts could be significantly detected in leaves and less abundantly in flowers and fruits. Analysis of wounded matured and ripened fruits revealed an inductive behavior for mRNA levels in the flesh of mature cherimoya after 16 h. Although the highest enzymatic activity was observed on rind, a consistent PPO activity was detected on flesh samples. A lack of correlation between PPO mRNA level and PPO activity was observed, especially in flesh tissue. This is probably due to the presence of monophenolic substrates inducing a lag period, enzyme inhibitors and/or diphenolic substrates causing suicide inactivation, and proenzyme or latent isoforms of PPO. To our knowledge this is the first report of a complete PPO sequence in cherimoya. Furthermore, the gene is highly divergent from known nucleotide sequences but shows a well conserved protein in terms of its function, deduced structure, and physiological role.

The stability of future power systems will be challenged by high shares of converter-based generation technologies (CBGTs). To prevent instability problems, it is essential to explore new technologies and control strategies able to counteract the negative effects that CBGTs may have. In this regard, promising technologies are battery energy storage systems (BESS), which can provide a wide range of benefits from a stability viewpoint. Current methodologies that quantify and allocate BESS in electrical networks have been developed from an economic perspective considering a steady-state formulation of the system. Accordingly, these allocation approaches do not exploit all the benefits that BESS can offer to system stability. This paper proposes a novel optimization methodology for efficient BESS allocation in systems with high levels of CBGTs. The model improves system stability by considering BESS with voltage support capability during contingencies. The allocation is solved by a genetic algorithm considering the transient voltages throughout the network busbars and their short circuit levels. The methodology was implemented in the 39 busbar New England system. Compared to traditional approaches, the proposed BESS allocation method enables significant improvements in the stability of the system during critical contingencies. Nomenclature connection busbar of BESS power system equivalent Thévenin impedance fault impedance