1、 General White paper/Second edition Use less energy retain quality Optimized high acid pasteurization.General Publisher Tetra Pak Processing Systems AB SE 221 86 Lund,Sweden Published Mars 2020 Tetra Pak International S.A No part of this publication may be duplicated in any form without the source b

2、eing indicated.3 CONTENTS Introduction.4 Who is this white paper for?.4 The takeaway.4 Established industry practice.5 Can we do better?.5 Heat resistance of microorganisms present in juice.6 Challenge test:Pilot scale testing of reduced pasteurization process.8 Verification of commercial sterility

3、in a commercial plant.9 Evaluation of product quality.9 Taste.10 Vitamin C degradation.10 Visual appearance.10 Conclusions.11 Process recommendations for juice,nectar and still drinks.12 Prerequisites.12 Reduction of energy consumption and increased flexibility.13 Tetra Pak your beverage PARTNER.14

4、4 INTRODUCTION Who is this white paper for?This white paper is for anyone in the beverage processing industry who works with drinking juices,nectars,or still drinks that are classified as high-acid products,with a pH 4.2.The evaluations and solutions outlined in this booklet will be of interest to p

5、lant managers,quality managers,technical managers and those working with JNSD products in a research or development capacity,as well as anyone concerned with minimizing operating costs and energy consumption in JNSD lines.The takeaway Findings from our research group indicate that many operators may

6、 be over-pasteurizing some of their drinking juices and wasting energy,money and time in the process.Our findings show that pasteurization recommendations can be optimized using less energy,while still retaining product quality.This is supported by detailed microbial analysis and evaluation of produ

7、ct quality after months of storage.5 ESTABLISHED INDUSTRY PRACTICE There is an established practice among fruit juice manufacturers and bottlers that fruit juices are commonly pasteurized twice before reaching the consumer.The purpose of these heat treatments is to make the juice product stable duri

8、ng its planned storage period.The primary pasteurization is done as soon as possible after juice extraction,or as a first step in the evaporator.This pasteurization is commonly done at 9598C for 10 to 30 seconds.The main objective is to inactivate enzymes from the fruit,but microorganisms are also i

9、nactivated during the pasteurization.Inactivation of enzymes generally requires more intensive pasteurization conditions than what is required to destroy microorganisms.The second pasteurization is carried out prior to filling the juice in its container.The purpose is to destroy the microorganisms t

10、hat occur as recontaminants in the fruit juice after bulk storage(NFC juice,Not From Concentrate)or in juice reconstituted from concentrate.The pasteurization conditions currently recommended by Tetra Pak for the second pasteurization of fruit juices with a pH below 4.2 are a temperature of 95C and

11、a holding time of 15 seconds.Can we do better?There are three important aspects to consider when reducing the heat treatment:food safety,microbiological stability and product quality.Our research team was assigned to answer three questions:Is it possible to decrease the heat load of the second paste

12、urization and contribute to more efficient energy practices in the juice industry?Will there be a difference in product quality if the pasteurization temperature is reduced from 95C to 80C?Is it possible to increase the temperature difference(dT)between the juice and the water on the media side of t

13、he heat exchanger to get increased flexibility,or will this impact product quality of the juice?6 HEAT RESISTANCE OF MICROORGANISMS PRESENT IN JUICE The first questions our research team asked were:Which microorganisms are relevant for the second pasteurization of juice and how heat-resistant are th

14、ey?The first pasteurization,in order to deactivate enzymes,kills most microorganisms,leaving the juice or concentrate commercially sterile.For NFC juice there is a risk that microorganisms enter the juice during transport or bulk storage and recontaminate the juice.If the juice or nectar is made fro

15、m concentrate,the recontamination may occur during storage and transport of the concentrate or during reconstitution with water.The water used for reconstitution should always be of high quality.The low pH of the juice is a natural hurdle inhibiting the growth of many types of microorganisms,but the

16、re are a few groups of microorganisms that can survive and grow in juice with pH4.2.Published data was used to evaluate heat resistance of relevant microorganisms.Different types of yeasts are commonly present in juice.Yeasts are normally not heat-resistant,i.e.they are easily killed during pasteuri

17、zation.Sometimes yeast forms ascospores,which require more heat treatment to be destroyed;otherwise they survive the heat treatment,start growing and spoil the juice after heat treatment.Moulds are also commonly present in juice.They are generally not heat-resistant and are therefore easily killed d

18、uring pasteurization.But there are certain types of moulds that are very heat-resistant,such as Byssochlamys fulva or Neosartorya fischeri.If these moulds are present it is not enough to use 95C with a 15 second holding time as the pasteurization process.They would require 110115C with a holding tim

19、e of 15-20 seconds to be inactivated.Acid-tolerant bacteria like Lactobacillus or Leuconostoc are commonly present but easily killed.Pathogenic bacteria like Salmonella,Listeria or E.coli O157:H7 can be present and survive in juice for a certain amount of time.They cannot grow and are easily destroy

20、ed by heat treatment.To avoid pathogenic bacteria in the juice it is important to always pasteurize the juice at a process that is no less than 72C for 15 seconds,which is the common pasteurization process for milk.Some types of bacteria are easily killed if they are in their vegetative state but ca

21、n form heat-resistant spores.Killing the spores requires a tougher heat treatment,depending on the bacterial species.Tests performed by our research team show that these bacteria1 cannot grow at pH4.2.Therefore,the heat treatment doesnt have to consider reduction of these types of spore-forming bact

22、eria.1 Bacillus megaterium,Bacillus licheniformis,Bacillus coagulans,Paenibacillus macerans,Paenibacillus polymyxa,Clostridium butyricum and Clostridium pasteurianum 7 The last type of bacteria that can grow and spoil the juice is Alicyclobacillus.These spoilage bacteria can even grow at pH 2,in par

23、ticular if the storage temperature is above 4045C.If possible,contamination by Alicyclobacillus should be avoided by choosing a juice concentrate of high quality.If there is a problem with Alicyclobacillus the juice has to be pasteurized at a higher temperature,i.e.110115C for 1520 seconds.Based on

24、the killing data available for the above-mentioned microorganisms,it is clear that there is a possibility of reducing the heat treatment of juices with pH4.2 from the current recommendation of 95C for 15 s.8 CHALLENGE TEST:PILOT SCALE TESTING OF REDUCED PASTEURIZATION PROCESS The second question for

25、 our research team was:Which is the lowest possible pasteurization process sufficient to produce a shelf-stable juice?Based on the heat resistance mentioned above,the yeast ascospores of Saccharomyces cerevisiae were chosen as target organisms during the challenge tests.The target was to prove that

26、the heat treatment was enough to obtain 9 log reductions of yeast ascospores.The yeast ascospores used during the test had a D63-value of 1.6 min and a z-value of 5.4C.Three tests were conducted at the Process Development Centre at Tetra Pak in Lund,Sweden.Yeast ascospores were added to apple juice

27、made from concentrate(2*107 ascospores per 300-litre batch).The juice was then pasteurized at three different heat treatment levels and aseptically packed in 250 ml portion packs(Tetra Brik Aseptic).The packages were stored at room temperature for three weeks and were inspected for blown packages as

28、 a sign of surviving yeasts.Table 1.Test results and theoretical log reductions of yeast ascospores*D63=1,6 min,z=5.4C.Apple juice,pH 3.5,2013,yeast ascospores used in this test*D60=22 min,z=6.5C.Buffer solution,pH 4.5,1982*D65=19 s,z=5.5C.Orange juice,pH 3.8,1997 The results confirm the theoretical

29、 calculations based on killing data found in the literature and show it is possible to reduce the heat treatment of juice to 80C with a 15-second holding time.Batch Heat treatment Temperature/holding time Results%Sterile packages Tetra Pak*Put&de Jong*Tetra Pak*1 65C/15 s 0%0.38 0.07 0.79 2 72C/15 s

30、 100%7.4 0.80 15 77C/15 s not tested 62 4.7 120 3 80C/15 s 100%222 14 421 9 VERIFICATION OF COMMERCIAL STERILITY IN A COMMERCIAL PLANT In order to verify our findings,a heat inactivation test was done together with one of our customers,Valio Oy,at their juice plant in Helsinki,Finland in June 2013.O

31、ne batch of 4,000 litres of orange juice(11.3Brix,pH 4.0)was pasteurized at 78C/22 s,which corresponds to a heat treatment at 80C/9.5 s,i.e.a lower heat treatment than 80C/15 seconds.The juice was packed in 16,000 Tetra Prisma Aseptic packages(250 ml).The packages were stored at room temperature(202

32、3C)for 3 weeks prior to inspection.None of the packages had any sign of gas formation due to unsterility.1,043 packages were transported to an internal laboratory at Tetra Pak in Lund,where they were opened and streaked on orange serum agar.All of them were commercially sterile.The result confirms t

33、he findings from the in-house test that 80C for 15 seconds gives enough heat load in the second pasteurization to produce a commercially sterile product.Evaluation of product quality To see if product quality is impacted by the reduced pasteurization temperature or if an increased dT will impact pro

34、duct quality of orange juice,the team processed orange juice made from concentrate(11.5Brix)at either 80C or 95C with dT ranging from 3C up to 25C at PDC at Tetra Pak in Lund.The juice was aseptically packed(Tetra Brik Aseptic packages 250 ml)and stored at room temperature (20-23C)for six months.Dur

35、ing storage,parameters such as taste,visual appearance and vitamin C content were evaluated.Table 2.Processing parameters for evaluation of product quality Sample Temperature dT Holding time A 80C 3C 15 s B 80C 15C 15 s Reference 95C 5C 15 s C 95C 12C 15 s D 95C 25C 15 s 10 Taste After six weeks of

36、storage,packages were sent to an external lab(IPSOS Marketing in Kristianstad,Sweden)to be evaluated by a trained taste panel.Three pairs were tested as triangle tests:1.Sample A vs.Sample D,the mildest vs.the toughest heat treatment 2.Reference sample vs.Sample C,impact of a small increase in dT at

37、 the same processing temperature 3.Reference sample vs.Sample D,impact of a large increase in dT at the same processing temperature The results showed there were no significant differences detected in any of the three tested pairs.Over the course of six months,triangle test 3 was performed monthly t

38、o determine if there was any detectable difference in taste during storage.On no occasion,neither immediately after processing nor after six months of storage,was the test panel able to detect any difference in taste between sample A and sample D.Vitamin C degradation The vitamin C content is an imp

39、ortant parameter to evaluate during juice storage.Vitamin C can be degraded by enzymatic reactions during storage if all enzymes are not destroyed during the heat treatment.Vitamin C can also be degraded due to oxygen.Small amounts of oxygen might penetrate flexible packages during storage or might

40、remain in the headspace of a sealed bottle or other package.To make sure the speed of vitamin C degradation was not impacted by the reduced pasteurization temperature(80C)or by the increased dT(up to 25C),the vitamin C content was measured by HPLC after 3.5 months and 7 months of storage.The results

41、 showed a normal reduction of vitamin C due to oxygen transmission into the package during storage.There was no difference between the samples processed at 80C or 95C.There was also no difference between the samples produced with low dT(3C)or with high dT(25C).Visual appearance Are consumers able to

42、 see any difference between juices processed at 95C compared to 80C?Or will consumers be able to spot a difference between juices processed with a normal low dT compared to a very high dT?There is a difference in colour during storage,as juice normally darkens over time,but results from our research

43、 team show no difference between the different juice samples with the same storage time.11 Conclusions The results show it is possible to reduce the pasteurization process for the second pasteurization of juice,nectar and still drinks from 95C/15 seconds to 80C/15 seconds and still obtain a safe and

44、 commercially sterile product.For juice made from concentrate there will be no difference in product quality if the pasteurization process is reduced or if the dT is increased up to 25C.12 PROCESS RECOMMENDATIONS FOR JUICE,NECTAR AND STILL DRINKS The following pasteurization process recommendations

45、are based on the outcome of the investigation by our research team.Prerequisites Turbulent flow required Content of Alicyclobacillus negative in 10 g/10 ml Content of Byssochlamys negative in 10 g/10 ml Table 3.Process recommendations for juice,nectar and still drinks*Divert temperature:3C below set

46、-point*Ruptured orange cell sacks,max.length 5 mm Product Set point/holding time*Juice NFC or from concentrate,second pasteurization,pH4.2 80C/15 s Juice,first pasteurization,enzyme deactivation 9598C/1030 s Nectar,pH4.2 80C/15 s if turbulent flow Still drinks,pH4.6 138C/4 s Juice with 10%pulp*95C/1

47、5 s Juice,Nectar,Still drinks with particles Based on particle size 13 REDUCTION OF ENERGY CONSUMPTION AND INCREASED FLEXIBILITY A decrease in heat load will mean large potential savings of energy consumption.If the pasteurization process is reduced from 95C/15 seconds to 80C/15 seconds there will b

48、e a 19%reduction of energy consumption.With the additional possibility of increasing the dT,juice producers will gain considerable flexibility when it comes to heat exchanger design and during changes in capacity.A heat exchanger designed by us aimed for processing juice is normally designed with a

49、dT of 3-5C.An increased dT means that the same heat exchanger can be designed to handle products with different viscosities and different product capacities.The calculations have been based on a reference line processing 22,000 litres of orange juice per hour in a Tetra Therm Aseptic Drink(16 hours/

50、day,5 days/week,50 weeks/year,1 hour of cleaning/day).Table 4.Energy consumption,energy cost and carbon footprint Cost calculation based on prices in Europe:1 kWh heat=1.65 kg steam,1 kg steam=0.035 EUR,1 kWh cooling=0.025 EUR Heat treatment process,22.000 l/h 95C/15 s 80C/15 s Difference Heating lo

51、ad,kW 430 354 Cooling load,kW 186 107 Energy cost,per kEUR/year 99 80-19%Carbon footprint,kg CO2/1000 litre 6.7 5.4-20%14 TETRA PAK YOUR BEVERAGE PARTNER We offer complete line concepts and technology support for JNSD producers as well as producers of many other beverages and food products thanks to

52、 our well established industrial and technology profile:Extensive knowledge of processing technology,as well as how best to implement them Product Development Centres and dedicated technology specialists Valuable knowledge and experience through partnerships with suppliers of technology,ingredients

53、and supplies Processing modules and line concepts for a variety of technologies End-to-end offerings,handling everything from incoming raw ingredients to pallets of finished products on your loading dock As an innovator,we actively explore and develop the challenges of the beverage industry.We colla

54、borate with customers,universities,and other business partners to develop new applications and find the best solutions for producing new products with flexibility.We develop customized solutions for your needs and maintain a leading position in developing new process line concepts.At our Product Dev

55、elopment Centres,customers can carry out product trials together with our specialists with unique comprehensive expertise in food processing and packaging.The centres provide highly flexible pilot plant facilities for processing and packaging trials,which ensures fast and reliable industrial scale-u

56、p.Customers can experiment with recipes and use the latest processing equipment.We also have pilot plants for rental where trials are conducted for customers on-site with the support of our expertise.Our network of partners is ready to assist you in many ways with your business and technical questio

57、ns regarding food processing issues.Feel free to contact your Tetra Pak representative or send an e-mail to:Knutove.A,Technical Product Manager Andreas.M,Product Manager Birgitta.S,Microbiology Specialist Christer.L,Food Technologist 15 Tetra Pak and Protects Whats Good are trademarks belonging to the Tetra Pak G Tetra Pak International S.A,Tetra Pak Processing system AB,2020