Lerp Material Color inside Update Loop

LerpColor.cs

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class LerpColor : MonoBehaviour {

	public float lerpDuration = 2;

	public Slider slider;
	public Text textTime;

	Material mat;
	Color originalColor;
	Color targetColor = Color.clear;

	float lerpCounter = 0;
	bool isLerping = false;

	float timeCounter=0;

	void Start () 
	{
		mat = GetComponent<Renderer> ().material;
		originalColor = mat.color;
	}
	
	void Update () 
	{
		if (Input.GetKeyDown (KeyCode.Space)) 
		{
			lerpCounter = 0;
			isLerping = !isLerping;
			slider.value = lerpCounter;

			timeCounter = 0;

			textTime.text = "Lerp: " + lerpCounter + " | Time: " + timeCounter;
			mat.color = originalColor;
		}

		if (isLerping) 
		{
			lerpCounter += Time.deltaTime/lerpDuration;
			mat.color = Color.Lerp (originalColor, targetColor, lerpCounter);

			timeCounter += Time.deltaTime;

			slider.value = lerpCounter;
			textTime.text = "Lerp: " + lerpCounter + " | Time: " + timeCounter;

			if (lerpCounter >= 1) {
				isLerping = false;
			}
		}
	}
	
}