The primitive baptist insist that only real wine and unleavened bread may be used. From their website Q&A:

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Question: Why do Primitive Baptists use real wine and real unleavened bread in communion?

While scriptural descriptions of the original communion use the terms bread, the cup, and fruit of the vine, it may be conclusively inferred that the bread was unleavened and that the drink was fermented wine. This follows from:

The communion took place immediately after the Passover. This was a time in which leavened bread was prohibited, both by scriptural law and by Jewish tradition (Ex 12:3-8, Num 9:9-11, Deut 16:1-3, Mt 26:17, Mk 14:12, Lk 22:7).
Leaven is used in the scriptures as an emblem of sin (Lk 12:1, I Cor 5:6-8, Gal 5:7-9) and is therefore an unsuitable representative of the Lord's body.
Wine is symbolically consistent with unleavened bread in that neither contain leaven. On the other hand, unfermented grape juice would contradict all that is portended by the unleavened bread because grape juice typically does contain leaven. There are some who erroneously assert that the opposite is true - that wine contains leaven but grape juice does not. The reader is invited to consult any authority on wine chemistry to resolve the matter.
Wine was a traditional part of the Jewish Passover.
Without modern methods of refrigeration, grape juice could not be preserved for all times of the year. The Passover season was not conducive to grape juice since it was well between harvests.
The Corinthians obviously used a fermented substance in their communion service since they perverted it into a drunken festival (I Cor 11:20-30). Paul condemns them for their impiety and excesses, but not for the usage of wine in communion.
The importance of adhering to the scriptural example in this matter cannot be questioned since God punished the Corinthians with illness and death for departing from it (I Cor 11:29-30). The usage of a leavened substance, such as grape juice, to represent the Lord is, in our opinion, a severe negligence, and is at risk of being chargeable as failure to discern the body of the Lord (I Cor 11:29).