Short Note #66: Sulfur Dioxide Determination in Beer

SO2 Determination in Beer by Distillation

SO2 Determination in Beer by Distillation

Short Note #66 introduces a novel procedure for the determination of Total sulfur dioxide (SO2) contents in beer using distillation. The most important advance stems from a calibration by means of a stabilized SO2 standard containing acetaldehyde simulating a beer matrix. A calibration equation is derived from a linear correlation of a series of SO2 determinations with SO2 standards and the calibration equation is applied in order to adjust measured SO2 results in samples. Total SO2 contents in a series of 5 beers were evaluated and results compared to the DTNB SO2 Method.

Request this Kjeldahl Distillation Short Note to see the full details and results of the study.

Introduction:
The DTNB SO2 Method is based on a spectrophotometric determination of the reaction product of SO2 with DTNB (5,5-dithiobis(2-nitrobenzoic acid). SO2 is entrained by a nitrogen stream into a buffered DTNB solution and the absorbance is measured at 415 nm. Steam distillation, as a possible alternative, does not fully recover SO2 from the sample without further optimization and adaption. The most important improvements stem from acidification of the sample with an acid mixture of methanol, water and orthophosphoric acid and a calibration by means of a stabilized
SO2 standard solution. The calibration reveals an excellent linear relationship between the determined SO2 amounts and the corresponding known amounts of standard solution. The linear equation is applied in the calculations to correct for Total SO2.

Beer Samples:
− Calanda Lager
− Heineken 1
− Heineken 2
− Prix Garantie Lager
− Heineken 3

Equipment:
− Distillation Unit K-355 with SO2 absorption glass (order number 048680)
− Metrohm DMP 785 Titrino
− Metrohm Pt-Titrode 6.0431.100
− Volumetric pipette 5 ml
− Glass beaker 500 ml

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Short Note #65: SO2 Determination in Wine

Distillation Unit K-355

Distillation Unit K-355

Short Note #65 on the distillation of wine describes a novel procedure for the determination of Total SO2 contents in wine. The most important advance stems from a calibration by means of a stabilized SO2 standard containing acetaldehyde simulating a wine matrix. A calibration equation is derived from a linear correlation of a series of SO2 determinations with SO2 standards and the calibration equation is applied in order to adjust measured SO2 results in samples. Total SO2 contents in a series of 11 wines were evaluated and results compared to the OIV SO2 Method.

Introduction:
The OIV SO2 Method is based on the entrainment of SO2 from the wine sample into a titration vessel by means of a nitrogen stream.

Simple steam distillation, as a possible alternative, does not produce results comparable to the OIV SO2 Method without further optimization and adaption.

The most important improvements stem from acidification of the sample with an acid mixture of methanol, water and ortho-phosphoric acid and a calibration by means of a stabilized SO2 standard solution containing acetaldehyde simulating a wine matrix. The calibration reveals an excellent linear relationship between the determined SO2 amounts and the corresponding known amounts of standard solution. The linear equation is applied in the calculations to correct for Total SO2.

Experimental:
The distillation unit should preferably be equipped with an acid resistant pump as available in the BUCHI K-355 (picture above) and the K-360.

The sample is acidified with the acid mixture and steam distilled into the specially designed BUCHI SO2 absorption vessel in which the SO2 reacts with a defined volume of iodine standard solution. Subsequently the distillate is back-titrated with Na-thiosulfate standard solution using a titrator suitable to carry out redox titrations.

>> Download the entire Short Note #65

Short Note #47: Protein Determination in Eggs According to Kjeldahl

Protein Determination in Eggs

Protein Determination in Eggs Using Kjeldahl

A simple and fast procedure for protein determination in eggs, as described in the AOAC 925.31 and LFGB § 64 L05.00-15, is introduced within this Short Note #47.

The sample is digested with sulfuric acid using the SpeedDigester K-436 or K-439, followed by distillation and titration with the Kjeldahl Sampler System K-370/K-371. The determined protein contents correspond to the values from literature (see Short Note #47 for details).

Introduction:
Protein determination is one of the key analyses performed in the food industry. The samples require digestion with sulfuric acid to convert nitrogen into ammonium sulfate. After conversion to ammonia through the alkalization with sodium hydroxide, the ammonia is distilled into a boric acid solution by steam distillation, followed by a titration with sulfuric acid solution. The nitrogen content is multiplied by a sample specific factor (6.25 for egg) to obtain the protein content.

Experimental:
Instrumentation: SpeedDigester K-436, K-439, Kjeldahl Sampler System K-370/K-371

Samples: Whole chicken egg, protein content 12.5 g/100g

Determination: Approx. 1.2 g of the homogenized sample were weighed in directly into a sample tube. A portion of 20 ml of sulfuric acid and 2 Kjeldahl tablets were added, and the digestion was performed using the “egg” method (K-439) or the parameters specified. After digestion the ammonia of the sample was distilled into a boric acid solution by steam distillation and titrated with sulfuric acid (See Short Note #47 for details).

The method was verified by using 0.13 g glycine as the reference substance.

Free Seminar: Kjeldahl and Extraction Solutions for Quality Control

Kjeldahl & Extraction for Quality Control

Kjeldahl & Extraction for Quality Control

By attending this FREE one day seminar you will learn essential technical information about our Kjeldahl and Extraction systems, as well as participate in open discussions regarding implementation, application, and method development.

This seminar in Montreal is the first in a technical seminar series BUCHI has developed to engage with existing customers and new prospects in their local areas. The seminars will be held in various locations all across North America, after this one we will be in Itasca, Illinois on July 27th and then Irving, Texas on August 4th.

The main focus of the technical seminars are how our Kjeldahl, Extraction and NIR products positively enhance quality control analysis. At all locations, the stages in a production process are subject to regular and demanding checks, from the reception of the raw materials to the formulation of the finished product.

These analyses require not only high performance coupled with accurate and reliable equipment, but also a reliable supplier. BUCHI not only manufactures market leading instruments, but we also provide method development and application support to our customers. For the past 70 years, BUCHI has developed techniques and equipment designed to simplify your workflow and make your lab and facility more productive. From the reception and inspection of raw material to the formulation of the finished product, learn how BUCHI equipment can help streamline your process.

Wednesday, July 6, 2011
9:00 am – 4:00 pm

Holiday Inn Expres Montreal Airport
10888, Cote-de-Liesse
Montreal, Quebec, H8T 1A6

For accommodations call the hotel directly at: 919-549-8885

Click To Register

Agenda:
9:00 Registration and continental breakfast

9:15 Introduction to BUCHI and product overview

9:30 Kjeldahl Solutions – Fundamentals of the Kjeldahl method for the determination of protein in food samples. Presented by William Ickes, BUCHI Corporation

•Method discussion of protein in food by Kjeldahl
•Comparisons of different Kjeldahl method strategies

10:15 Break

10:30 BUCHI automated Kjeldahl solutions – From the very basic to fully automated solutions for fast, reliable quality control determination of proten in food samples. Presented by William Ickes, BUCHI Corporation

•Introducing the New SpeedDigester digestion systems for the fastest digestion on the market
•Unique design of the Scrubber B-414 for neutralization of digestion vapors
•Fast 4 minute steam distillation from basic to autosampler system

11:15 Demonstration and hands-on: Kjeldahl instrumentation K-370
Open discussion and hands-on operation of instrument

12:00 Lunch – provided by BUCHI

1:00 Extraction Solutions – Fundamentals of Extraction techniques for the determination of fat/oil/pesticides in food samples. Presented by William Ickes, BUCHI Corporation

•Comparison of Soxhlet, Hot, and Pressurized Solvent Extraction
•Hydrolysis prior to extraction
•Importance of homogenization to the extraction process

1:45 Break

2:00 Automated Extraction Solutions. Presented by William Ickes, BUCHI Corporation

•Automated Soxhlet, Hot, and Pressurized Solvent Extraction units
•Hydrolysis units
•BUCHI B-400 Mixer

2:30 Demonstration of E-816 Sox
Open discussion and hands-on operation of instruments

Nitrogen & Protein Determination in Milk By Digestion

Protein Determination in Milk

Protein Determination in Milk

Nitrogen and Protein Determination in Milk by Digestion with Hydrogen Peroxide and Sulfuric Acid

Application Note #54 introduces a simple and very fast procedure for protein determination in milk and provides detailed steps for completing the process. BUCHI’s Kjeldahl application database lists more than 100 Kjeldahl and Non-Kjeldahl applications using dedicated BUCHI equipment: Download #54 and all our other Kjeldahl Application Notes online.

The sample is digested with hydrogen peroxide and sulfuric acid using the SpeedDigester K-436 or K-439, followed by distillation and titration with the Kjeldahl Sampler System K-370/K-371. The determined protein contents correspond to the results obtained with the Kjeldahl method.

Introduction:
The digestion with hydrogen peroxide 30% instead of Kjeldahl tablets for nitrogen and protein determination is a very fast (30 min instead of 85 min (K-439) or 100 min (K-436)) and environmentally friendly (free of any heavy metal) alternative to the classical Kjeldahl methods.

Instrumentation:
SpeedDigester K-436, K-439, with H2O2 suction module, Kjeldahl Sampler System K-370/K-371

Samples:
Whole milk UHT, partially skimmed milk UHT, and chocolate milk beverage: labeled protein contents 3 g/100ml (whole milk) and 3.5 g/100ml (partially skimmed and chocolate milk). Protein determinations according to the classical Kjeldahl method, measure 3.15% for the whole milk, 3.19% for the partially skimmed milk, and 3.30% for the chocolate milk beverage.

Determination:
Approx. 5 g of the homogenized sample were weighed directly into a sample tube. A portion of 20 ml of sulfuric acid was added, and the digestion was started using the parameters specified (See complete note for data). Initially, 15 ml of hydrogen peroxide 30% was added to the capillary funnel 2 minutes after the start of the digestion. Then, another 15 ml of hydrogen peroxide 30% was added to the capillary funnel 10 minutes after the start of the digestion. The method was verified by using 0.18 g tryptophan as the reference substance.

Short Note #45: Nitrogen and Protein Determination in Pharmaceuticals

A simple and fast procedure for nitrogen determination in pharmaceuticals according to the Kjeldahl method (semi-micro), as described in the European Pharmakopeia 6.0 / 2.05.08, is introduced in this study. Protein determination is calculated The sample is digested with sulfuric acid using the SpeedDigester K-436 or K-439, followed by distillation and titration with the KjelFlex K-360. There are no differences between the results obtained with the K-436 and the K-439 respectively.

Introduction: Nitrogen determination is one of the key analyses performed in quality control. The samples require digestion with sulfuric acid to convert nitrogen into ammonium sulfate. After conversion to ammonia through the alkalinization with sodium hydroxide, the sample is distilled into a boric acid receiver by steam distillation, followed by a titration with hydrochloric acid solution. The nitrogen content is multiplied by a sample-specific factor to obtain the protein content.

Sleeping Pill Samples

Sleeping Pill Samples


Experimental Instrumentation: SpeedDigester K-436, K-439, KjelFlex K-360

Samples: Sleeping pills and tranquilization drops

Conclusion: The determination of nitrogen contents in pharmaceuticals according to Kjeldahl using SpeedDigester K-436, K-439, and KjelFlex K-360 provides reliable and reproducible results with low relative standard deviations.

Short Note #24: Protein Determination in Beer According to Kjeldahl Method

Protein determination in beer according to kjeldahl

Protein Determination in Beer

This short note describes a simple and fast procedue for protein determination in beer according to the Kjeldahl method, as detailed in in the AOAC 920.53 regulations. Visit our Kjeldahl Applications section to download this short note and review all our other available application studies.

Introduction:
Protein determination is one of the key analyses performed in the food industry. The samples require digestion with sulfuric acid to convert nitrogen into ammonium sulfate.

After conversion to ammonia through the alkalinization with sodium hydroxide, the sample is distilled into a boric acid receiver by steam distillation, followed by a titration with sulfuric acid solution. The nitrogen content is multiplied by a sample-specific factor (6.25 for beer) to obtain the protein content.

Instrumentation:
Buchi SpeedDigester K-436, K-439, Buchi Kjeldahl Sampler System K-370, K-371

Samples:
Draft beer and Wheat beer. The protein content from draft beer is 0.50%.

Conclusion:
The determination of protein contents in chocolate according to Kjeldahl using SpeedDigester K-436, K-439, and Kjeldahl Sampler System K-370/K-371 provides reliable and reproducible results that correspond to the labeled values and literature [See Note for table data references] with low relative standard deviations. The total digestion time is approximately 90 min.