τρωγω in John 6: Proof of Transubstantiation?

John 6 is often touted as definitive biblical “proof” of the Roman Catholic dogma of Transubstantiation. In John 6:54, there is a shift in the verb being used in the Greek text, from εσθιω (used in vv. 50-53) to τρωγω (vv.54-58). According to some Catholic apologists, this represents a shift in the focus of Christ’s sermon, as the former verb can be understood in a figurative manner, but the latter verb is never used figuratively, but literally, that is, Christ is commanding the literal consumption of his flesh.

Catholic apologist, Robert Sungenis, while attempting to use this argument, traps himself when he appeals to Greek lexical sources which demonstrate that τρωγω can, and has been, used in figurative senses in Greek literature:

In Greek classical literature, trôgô referred to the act of chewing, gnawing, munching, nibbling or biting and sometimes with the general meaning of devouring. (Liddell and Scott, Greek English Lexicon, Oxford University Press, 1871; Walter Bauer, Greek English Lexicon of the New Testament, University of Chicago Press, 1979). Bauer mentions the fifth century BC writing of Aristophenes in which the wording “ο τρωγων μου τον αρτον” (“the one eating my bread”) and the second century BC writing of Polybius, “δυο τρωγομεν αδελφοι” (“two brothers eat”) are instances illustrating comradeship. (Robert A. Sungenis, Not by Bread Alone: The Biblical and Historical Evidence for the Eucharistic Sacrifice [2d ed.: Catholic Apologetics International Printing, 2009], 154 n. 163).

Another element that undercuts the Catholic appeal to John 6:54f is the fact that the text uses the phrase, ο τρωγων, which is a present active participle. In Catholicism, one partakes, iteratively, the sacrament of the Eucharist, but it is not an on-going process in the sense of 24/7,  not merely iteratively, which is required by the grammar of John 6:54.

Here is the entry to τρωγω in BDAG (A Greek-English Lexicon of the New Testament and Other Early Christian Literature [3d ed] emphasis added):

469  τρώγω • τρώγω (Hom. et al.; TestJob 12:2; SIG 1171, 9; PGM 7, 177; Sb 5730, 5. Not found in LXX, EpArist, Philo or Joseph. B-D-F §101 s.v. ἐσθίειν; 169, 2; Rob. 351; JHaussleiter, Archiv für lat. Lexikographie 9, 1896, 300-302; GKilpatrick in: Studies and Documents 29, ’67, 153) to bite or chew food, eat (audibly), of animals (Hom. et al. ‘chew, nibble, munch’) B 10:3.—Of human beings (Hdt. et al. and so in Mod. Gk.) τὶ someth. (Hdt. 1, 71, 3 σῦκα; Aristoph., Equ. 1077) B 7:8. ὁ τρώγων μου τὸν ἄρτον as a symbol of close comradeship (Polyb. 31, 23, 9 δύο τρώγομεν ἀδελφοί) J 13:18 (s. Ps 40:10 ὁ ἐσθίων ἄρτους μου, which is the basis for this pass.). W. gen. (Athen. 8, 334b τῶν σύκων) Hs 5, 3, 7. Abs. B 10:2. W. πίνειν (Demosth. 19, 197; Plut., Mor. 613b; 716e) Mt 24:38. J uses it to offset any tendencies to ‘spiritualize’ the concept so that nothing physical remains in it, in what many hold to be the language of the Lord’s Supper ὁ τρώγων τοῦτον τὸν ἄρτον 6:58. ὁ τρώγων με vs. 57. ὁ τρώγων μου τὴν σάρκα (w. πίνων μου τὸ αἷμα) vss. 54, 56.—B. 327. DELG. M-M. TW.