Protein Content Analysis (Kjeldahl Method Principles)
📌 The objective of this test is to determine the crude protein content of a feed or sample material.
🧪 The principle involves determining the nitrogen (N) content and multiplying the result by a factor of 6.25 to estimate the crude protein percentage.
🛠️ Key apparatus includes a distillation apparatus (Kjeldahl apparatus), digestion apparatus (Kjeldahl block digester), analytical balance, and glassware like Erlenmeyer flasks.
🧪 Chemicals utilized are concentrated $\text{H}_2\text{SO}_4$, $\text{NaOH}$ 45%, $\text{H}_3\text{BO}_3$ (Boric Acid) 4%, $\text{CuSO}_4$ and $\text{K}_2\text{SO}_4$ as catalysts, and standardized $\text{HCl}$ ($0.1\text{ N}$) for titration.

Procedure Highlights
🔥 The addition of concentrated $\text{H}_2\text{SO}_4$ during the digestion step must be done slowly by flowing the liquid down the wall of the digestion flask, held at a $45^\circ$ inclination.
💧 The titration step involves monitoring the volume of titrant consumed, which is crucial for the final calculation.
🧪 A blank sample (titran blanko) is necessary to account for reagents contributing to the nitrogen measurement.

Crude Protein Calculation Formula
🧮 The formula for calculating crude protein percentage ($\text{CP}$) in the sample is:
$$\text{CP} = \frac{(\text{Titran Sample} - \text{Titran Blanko}) \times \text{N}_{\text{HCl}} \times 0.014 \times 6.25}{\text{X gram Sample}} \times 100$$
(Note: The provided audio states $0.014$ and omits the $100$ multiplier typically associated with percentage calculation, assuming $0.014$ accounts for volume/weight normalization based on context. The formula uses the components listed in the audio: $\text{Titran Sample}$ (in mL), $\text{Titran Blanko}$ (in mL), $\text{N}_{\text{HCl}}$ (Normality of $\text{HCl}$), $0.014$ (equivalence factor), $6.25$ (conversion factor), and $\text{X}$ (sample weight in grams)).
📊 Components include: $\text{Titran Sample}$ (mL used for sample titration), $\text{Titran Blanko}$ (mL used for blank titration), $\text{N}_{\text{HCl}}$ (Normality of $\text{HCl}$ solution, $0.1\text{ N}$ stated for reagent), $6.25$ (protein conversion factor), and $\text{X}$ (sample weight used).

Key Points & Insights
➡️ Perform the Kjeldahl method to accurately quantify total nitrogen which is then converted to an estimate of crude protein.
➡️ Ensure slow and controlled addition of concentrated $\text{H}_2\text{SO}_4$ during digestion to manage the exothermic reaction safely.
➡️ Record the exact volumes of titrant used for both the sample and the blank to ensure accurate calculation of the net nitrogen content.

📸 Video summarized with SummaryTube.com on Dec 29, 2025, 05:45 UTC