How to set a limit for my player rotation ?

Hi Guys ! I've created this script to make "jump" and a little rotation for my player i want to stop my"CreamUP" rotation wen i reach -90 on X axis and i want to stop my "Update" rotation wen i reach 90 on x axis

There is a way for this ? I try with the If statement but the rotation in game seems different from the scene rotation so when i put "if (gameobject.Transform.eulerAngles.x <= 90)" the rotation in game explodes XD Thanks guys :)

  using UnityEngine;
  using System.Collections;

 public class Player_Controller : MonoBehaviour 
 {
 private Rigidbody creamBody;
 public Animation creamJump;

 // Use this for initialization
 void Start () 
 {
     creamBody = gameObject.GetComponent<Rigidbody> ();
     creamJump.Play ("Take 001");
 }
 
 // Update is called once per frame
 void Update () 
 {
     creamBody.AddForce (0, -30, 0);
     gameObject.transform.Rotate (new Vector3 (1.35f, 0, 0));
 }

 public void CreamUP()
 {
     creamBody.velocity = new Vector3 (0, 17, 0);
     gameObject.transform.Rotate (new Vector3 (-40, 0, 0));
 }
 

}