The serious abuses which invalidate the Mass are all those which inhibit transubstantiation, that is fail to bring about Jesus' True Presence in the Eucharist. The Church has very specifically defined what must - and must not - occur so that transubstantiation will result. There are four conditions required for a valid Consecration resulting in the miracle of transubstantiation. All of these conditions must be present for a valid Consecration. This is dogma. Therefore, anyone who denies these requirements is liable to heresy.
Note that this article deals with only the Western Latin Rite Church. There are different rules for Eastern Rite Catholic Churches, such as Byzantine Catholic. For the Western Latin Rite Catholic Church, valid matter consists of wheat unleavened bread and grape wine.
Canon 924 §1 The most holy Sacrifice of the Eucharist must be celebrated in bread, and in wine to which a small quantity of water is to be added. §2 The bread must be wheaten only, and recently made, so that there is no danger of corruption. §3 The wine must be natural, made from grapes of the vine, and not corrupt.
Canon 926 In the Eucharistic celebration, in accordance with the ancient tradition of the Latin Church, the priest is to use unleavened bread wherever he celebrates Mass.
GIRM 282. According to the tradition of the entire Church, the bread must be made from wheat; according to the tradition of the Latin Church, it must be unleavened.
GIRM 283. The nature of the sign demands that the material for the eucharistic celebration truly have the appearance of food. Accordingly, even though unleavened and baked in the traditional shape, the eucharistic bread should be made in such a way that in a Mass with a congregation the priest is able actually to break the host into parts and distribute them to at least some of the faithful. (When, however, the number of communicants is large or other pastoral needs require it, small hosts are in no way ruled out.) The action of the breaking of the bread, the simple term for the Eucharist in apostolic times, will more clearly bring out the force and meaning of the sign of the unity of all in the one bread and of their charity, since the one bread is being distributed among the members of one family.
GIRM 284. The wine for the Eucharist must be from the fruit of the vine (see Lk 22:18), natural, and pure, that is not mixed with any foreign substance.
GIRM 285. Care must be taken to ensure that the elements are kept in good condition: that the wine does not turn to vinegar or the bread spoil or become too hard to be broken easily.
Any other matter of Altar breads, especially forms becoming more popular with dissenters such as cakes or cookies, invalidates transubstantiation. St. Thomas Aquinas also covers this requirement in Summa Theologica (Third Part, Question 74, Articles 1 through 8). There are rare exceptions where Bishops may grant individual priests with allergies or alcohol problems the right to use low-gluten altar breads or mustem (a specific form of grape juice with fermentation suspended). It is gravely sinful for a priest to celebrate Mass knowing the matter is invalid.
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