Das Röstprofil folgt der Röstkurve.

Because folgen takes the dative case, not the accusative.

• The subject is Das Röstprofil.
• The verb is folgt.
• The thing being followed is der Röstkurve, and that noun must be in the dative.

The noun die Röstkurve is feminine, so its article changes like this:

• nominative: die Röstkurve
• accusative: die Röstkurve
• dative: der Röstkurve

So in this sentence, der Röstkurve is correct because folgen + dative is the rule.

Yes, in its normal meaning of to follow, folgen takes a dative object.

Examples:

• Ich folge dem Mann. = I follow the man.
• Wir folgen der Straße. = We follow the road.
• Das Röstprofil folgt der Röstkurve.

This often surprises English speakers because English follow takes a direct object, but German folgen does not.

The subject is Das Röstprofil.

You can tell because:

• it agrees with the verb folgt (3rd person singular)
• it is in the nominative case
• it is the thing doing the action of following

So the basic structure is:

• Das Röstprofil = subject
• folgt = verb
• der Röstkurve = dative object

Folgt is the 3rd person singular present tense of folgen.

The present-tense forms are:

• ich folge
• du folgst
• er/sie/es folgt
• wir folgen
• ihr folgt
• sie/Sie folgen

Since das Röstprofil is singular, the verb is folgt.

Because Profil is a neuter noun in German: das Profil.

Since Röstprofil is a compound noun, the gender is determined by the last part of the compound, which is Profil.

So:

• das Profil
• therefore das Röstprofil

This is a very important rule in German compound nouns: the final element usually decides the gender.

Yes. Röstprofil is a compound noun made from:

• Röst- = roasting / roast-related
• Profil = profile

So literally it is something like roasting profile or roast profile.

German uses compound nouns very freely. The final part is the main noun, and the earlier part modifies it.

The same is true for Röstkurve:

• Röst-
  • Kurve
• literally: roasting curve / roast curve

Also remember that all nouns in German are capitalized, so both Röstprofil and Röstkurve begin with capital letters.

It comes from the verb rösten, meaning to roast.

So:

• rösten = to roast
• Röst- = roast-/roasting- as a compound element

The ö is part of the normal spelling of the word family. It is not added just because of grammar in this sentence.

A helpful rough guide for an English speaker:

• Röstprofil ≈ RERST-pro-feel
• Röstkurve ≈ RERST-koor-vuh

A few pronunciation points:

• ö does not exist exactly in English. It is somewhat like saying eh or er with rounded lips.
• w in German sounds like English v.
• final -e in Kurve is a light uh sound.
• Profil is stressed on the second syllable: pro-FIL
• Röstkurve is usually stressed on the first part: RÖST-kur-ve

Yes, but the normal order here is the most straightforward:

• Das Röstprofil folgt der Röstkurve.

German is a verb-second language in main clauses, so the finite verb folgt must stay in the second position. But something else can come first for emphasis:

• Der Röstkurve folgt das Röstprofil.

This is grammatically possible, but less neutral. Because folgen takes the dative, der Röstkurve is still not the subject, even when it comes first.

So word order can change, but the case endings still tell you what each noun is doing.

Because German finite verbs do not need anything like English to in a normal present-tense statement.

Compare:

• English: The roast profile follows the roast curve.
• German: Das Röstprofil folgt der Röstkurve.

The verb folgt already means follows.
You would only see zu with another verb in certain constructions, not in a simple sentence like this.

No. That is a very common learner mistake.

Why it is wrong:

• die Röstkurve is nominative/accusative feminine
• but folgen requires the dative
• the dative form is der Röstkurve

So the correct sentence is:

• Das Röstprofil folgt der Röstkurve.

Not always. It is often equivalent, but you must watch the grammar.

In meaning, folgen can be used for:

• physically following someone or something
• following a path, road, line, or curve
• following advice, logic, or instructions

Examples:

• Ich folge dir. = I’m following you.
• Folgen Sie der Straße. = Follow the road.
• Ich kann dir nicht folgen. = I can’t follow you / I can’t understand your reasoning.

So the meaning is often close to English follow, but the grammar is different because German uses the dative.

A good shortcut is:

folgen + dative

Then map the sentence like this:

• Das Röstprofil = nominative subject
• folgt = present tense verb
• der Röstkurve = dative object

If you remember just one thing from this sentence, make it this:

After folgen, ask yourself: “What is in the dative?”