[1316]*1316Opinion for the court filed by Circuit Judge DYK.
Opinion eoneurring-in-part and dissenting-in-part filed by Circuit Judge SCHALL.
DYK, Circuit Judge.
Yoon Ja Kim, the holder of U.S. Patent No. Re. 36,355 (“the '355 patent”), appeals from the district court’s judgment of non-infringement of claim 5 and its dependent claims and claim 10 in favor of ConAgra Foods, Inc. (“ConAgra”). ConAgra cross-appeals from the district court’s judgment that the patent claims are not invalid. We affirm in all respects.
BACKGROUND
The patent in this case relates to bread-making. Oxidizing agents are used during the breadmaking process to strengthen dough, increase loaf volume, contribute to fíne crumb grain, and increase shelf life. Since the early 1900’s, potassium brómate was widely used as a slow-acting oxidant to improve the quality of bread. However, by the 1990’s, there was growing concern about the carcinogenic effects of potassium brómate, and the Food and Drug Administration encouraged the baking industry to seek suitable alternatives. Kim, a food chemist, believed that a combination of ascorbic acid and food acid would serve as a suitable alternative to potassium bró-mate in the breadmaking process, and applied for a patent on that composition. On April 23, 1996, Kim obtained U.S. Patent No. 5,510,129 for a potassium brómate re-placer composition. However, a few weeks later, Kim surrendered that patent to the Patent and Trademark Office (“PTO”) and filed a reissue application, alleging that an error had arisen during prosecution. After prosecution of her reissue application, Kim obtained the '355 reissue patent on October 26,1999.
On April 9, 2001, Kim filed suit against ConAgra alleging that ConAgra induced the infringement of independent claims 5 and 10 of the reissued '355 patent.1 Claims 5 and 10 were newly added during prosecution of the reissue application. The accused conduct was that ConAgra required licensees of its “Healthy Choice®” brand name to use recipes provided by ConAgra. Kim alleged that the Healthy Choice® Natural Wheat product infringed claim 5 and that the Healthy Choice® 7-Grain and Whole Grain products infringed claim 10.2 ConAgra stipu[1317]*1317lated that the bread recipes used in the accused products included ascorbic acid and food acid in the ranges specified in claims 5 and 10 of the '355 patent. Claim 10 differs from claim 5 in that it contains the additional limitation of yeast.
On June 30, 2003, ConAgra filed a counterclaim for a declaratory judgment of invalidity and noninfringement of the '355 patent.3 On November 10, 2003, ConAgra moved for summary judgment of invalidity based on the recapture rule. On March 26, 2004, the district court (Judge William T. Hart) denied ConAgra’s motion. The case then proceeded to trial. After each party’s case-in-chief, the opposing party moved for judgment as a matter of law (“JMOL”) under Rule 50 of the Federal Rules of Civil Procedure, and the district court reserved ruling on both motions. On October 13, 2004, a jury found that the asserted claims of the '355 patent were not invalid; that ConAgra had induced infringement of claim 10 with the licensing of its Healthy Choice ® 7-Grain and Whole Grain products, but that the inducement was not willful; and that claim 5 and the dependent claims were not infringed. ConAgra renewed its motion for JMOL, arguing invalidity and noninfringement. On April 28, 2005, the district court partially granted ConAgra’s motion for JMOL, finding that the '355 patent was not invalid but that claim 10 was not infringed. The district court entered final judgment on April 28, 2005, finding the '355 patent not infringed and not invalid.
Kim timely appealed the judgment of noninfringement, and ConAgra cross-appealed the judgment that the claims were not invalid. We have jurisdiction under 28 U.S.C. § 1295(a)(1) (2000).
DISCUSSION
I
Kim urges that we (1) reverse the district court’s grant of JMOL of noninfringement of claim 10, (2) overturn the jury’s verdict of noninfringement of claim 5, and (3) find both claims 5 and 10 willfully infringed by ConAgra.
Kim contends that the jury charge rested on an incorrect construction of the phrase “[a] potassium brómate replacer composition” in both claims 5 and 10 of the '355 patent.4 Alternatively, Kim argues that even under the district court’s claim construction, the accused products infringed.
A Claim construction
As part of its claim construction, the district court instructed the jury that “[t]o infringe one of the claims of the '355 Patent, a bread must (a) contain ingredients in the proportions in claim 5, 6, 7, 8, or 10 and, (b) in that particular bread, the ingredients must act as a potassium brómate replacer, that is, the ingredients must perform essentially the same junction in the production of that bread as would potassium brómate.” J.A. at 113 (emphasis add[1318]*1318ed). The court also provided the jury with the following definition: “Potassium Bró-mate is a slow acting oxidant once commonly used in the breadmaking process. Its function in the breadmaking process is to strengthen the dough, increase loaf volume, and contribute to fine crumb grain.” J.A. at 147 (emphasis added). Kim objected to these jury instructions. On appeal, Kim concedes that “potassium brómate re-placer” is a claim limitation, but argues that a “potassium brómate replacer” is simply a “potassium brómate substitute,” which she in turns describes as a composition that is present when potassium bró-mate is not.
Upon review of the specification, we agree with the district court’s claim construction. “[CJlaims must be read in view of the specification, of which they are a part.” Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed.Cir.2005) (en banc) (internal quotation marks omitted). The specification “is the single best guide to the meaning of a disputed term.” Id. (internal quotation marks omitted). Here, while the specification does not explicitly define the term “potassium brómate replacer,” it does make clear that the claimed potassium brómate replacer is an oxidizing agent. In fact, the specification explicitly states that “the potassium brómate replacer provided in the present invention is a more effective oxidant than potassium brómate.” '355 patent, col. 3, 11. 1-2. The specification also describes oxidants, or oxidizing agents, as follows:
Oxidizing agents provide strengthening of dough during the manufacturing process of yeast-leavening products. As a result, oxidizing agents are used to provide greater loaf volume, improve internal characteristics such as grain and texture, and enhance symmetry and keeping quality of yeast-leavening products.
'355 patent, col. 1,11. 22-27.
Thus, the specification reveals that the claimed potassium brómate replacer functions as an oxidant and that oxidants strengthen dough, increase loaf volume, and contribute to fine crumb grain. The specification also states that, “the present invention is particularly useful [in] that it provides natural ascorbic acid as the only oxidizing agent in dough that is effective and functional throughout the entire manufacturing process.” '355 patent, col. 1, 11. 57-60 (emphasis added). When the claim limitation is read against this backdrop, it is clear that the potassium brómate repla-cer must be functional. The district court’s construction of “potassium brómate replacer” as a-composition that performs essentially the same function in the production of bread as would potassium bró-mate (by strengthening the dough, increasing loaf volume, and contributing to fine crumb grain) is, therefore, supported by the specification. We thus find no error in the district court’s construction of “potassium brómate replacer composition.”5
[1319]*1319We also agree with the district court’s determination that “there is no indication that the three [potassium brómate replacer ingredients] must first be combined together to form a stand-alone repla-cer composition and then be added as a whole to the bread mix or dough.” J.A. at 206. We see nothing in the '355 patent which supports ConAgra’s argument for a contrary claim construction.
Relying on various references in the specification and prosecution history which describe Kim’s potassium brómate replacer as functioning as a slow acting oxidant, the dissent urges that “potassium brómate replacer” should be construed as “a slow acting oxidant that is functional throughout the entire manufacturing process.” Diss. Op. at 2. Neither party urged this construction in the district court or in this court. While we may have the authority to adopt claim constructions which have not been proposed by either party, see Exxon Chem. Patents, Inc. v. Lubrizol Corp., 64 F.3d 1553, 1556 (Fed.Cir.1995), we should be hesitant to do so. Considering the dissent’s proposed construction on the merits, we find it to be incorrect. The mere fact that one object of the invention is to produce a slow acting oxidant which is functional throughout the entire manufacturing process does not mean that this particular feature was adopted as a limitation in each claim of the patent. The specification does not require that the potassium brómate replacer must necessarily be a slow acting oxidant, only that particular potassium brómate replacers perform that function. '355 patent, col. 2.11. 25-33. Thus the fact that the patent here discloses the advantages of a slow acting oxidant does not mean that all the claims are directed to such an oxidant. See E-Pass Tech., Inc. v. 3Com Corp., 343 F.3d 1364, 1368-69 (Fed.Cir.2003). Indeed, Kim chose to claim a “slow acting” oxidant in dependent claim 7, while her independent claims were directed to a more general potassium brómate replacer. The doctrine of claim differentiation suggests that the independent claims here should not include explicit limitations of a dependent claim. See Phillips, 415 F.3d at 1315 (“[T]he presence of a dependent claim that adds a particular limitation gives rise to a presumption that the limitation in question is not present in the independent claim.”); Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 910 (Fed.Cir.2004). The prosecution history does not compel a different construction.
B Infringement
Kim argues in the alternative that, even under the district court’s claim construction, ConAgra induced infringement and therefore the district court erroneously granted JMOL of noninfringement of claim 10. “A finding of inducement requires both an underlying instance of direct infringement and a requisite showing of intent.” Fuji Photo Film Co. v. Jazz Photo Corp., 394 F.3d 1368, 1377 (Fed.Cir.2005).
It was undisputed that the accused products included the amount of ascorbic acid, food acid, and yeast in the proportions listed in claim 10. The question was whether the claimed ingredients in the accused products satisfied the functionality limitations. Kim’s evidence of infringement on the question of functionality was by analogy. She testified that her patented composition strengthened dough, increased loaf volume, and contributed to fine crumb grain. Since the accused products included the same ingredients as the patented composition, Kim simply assumed that they had the same effects on dough as did the patented composition.
However, with respect to a “consisting essentially of’ claim, there is no infringement where the accused product contains additional, unclaimed ingredients [1320]*1320that materially affect the basic and novel properties of the invention. See PPG Indus. v. Guardian Indus. Corp., 156 F.3d 1351, 1354 (Fed.Cir.1998). Here, ConA-gra’s 7-Grain and Whole Wheat products contained additional ingredients beyond ascorbic and food acids, such as vital wheat glutten, ferrous sulfate, and dough strengthening enzymes. Based on testimony of its expert witness, ConAgra argued that the additional ingredients materially affected functionality. While Kim, who was qualified as an expert,6 offered conclusory testimony that the additional ingredients would not have materially affected the pertinent characteristics of the bread, Kim did not support this determination with any examinations or tests of the actual accused products. Under the circumstances of this case, we agree with the district court that Kim did not prove infringement because she presented no testimony based on the accused products themselves that supported a finding of infringement. We thus agree that the district court properly granted JMOL to ConAgra on claim 10.
Regarding claim 5, Kim argues that the jury erroneously found nonin-fringement. Kim again relied on the fact that the accused Natural Wheat product contained the ingredients in the proportions specified under claim 5, and that her patented potassium brómate replacer, as set forth in claim 5, strengthened dough. However, Kim again did not conduct any test based on the accused product to determine whether those ingredients had the required effect. The jury’s verdict of non-infringement of claim 5 was therefore supported by substantial evidence.7
Having concluded that ConAgra did not induce infringement of claim 5 or claim 10, there is no need to address Kim’s argument on willfulness.8
II
In its cross-appeal, ConAgra argues that the asserted claims of the '355 patent are invalid because they improperly recapture material that Kim surrendered during prosecution of her original patent, and that the '355 patent is invalid as anticipated by, and obvious over, the prior art.9
A Recapture of Surrendered Subject Matter
Understanding ConAgra’s recapture argument requires that we first review the prosecution history of the '355 patent. On November 5, 1993, Kim filed her original patent application for a composition and process for controlling the oxidation rate of ascorbic acid in breadmaking. In perti[1321]*1321nent part, claims 1-5 of this application were directed to a composition including an unspecified amount of ascorbic acid and 0.03-0.2 parts organic acid by weight of flour in the dough. The remaining claims included an additional phosphate salt limitation. After some initial correspondence between Kim and the PTO, the examiner rejected claims 1-3, 5-9, 13-17, and 19 as obvious in light of the Tanaka reference (U.S. Patent No. 4,296,133 (filed Aug. 24, 1979)) and two other references. With respect to claim 1, the examiner noted that the prior art references disclosed “bread doughs containing the combination of ascorbic acid with organic acids” and that “[a]s far as the claim is understood, the reference shows the same combination claimed.” J.A. at 2735. The examiner also noted that “[t]he limitation of the phosphate salt recited in some of the claims is not considered patentably significant. [Other references] disclose the use of the claimed phosphate salts in bread doughs.” Id.
On September 19, 1994, Kim abandoned her original application and filed a continuation-in-part application. The sole independent claim, claim 1, included an ascorbic acid limitation (15-250 ppm), a food acid limitation (0.02-0.15 parts per 100 parts of flour), and a phosphate limitation (0.15-0.40 parts per 100 parts of flour). In filing her continuation-in-part application, Kim noted that the invention uses a “composition comprising ascorbic acid, food acid, and phosphate as oxiding agent repla-cers.” J.A. at 2776. The examiner initially rejected all the claims as obvious in light of the Tanaka and other references. After a telephone conference with Kim, the examiner amended the application by changing the method claims into composition claims and by changing the transition phrase from “comprising” to “consisting essentially of.” The examiner allowed the claims as amended, noting that “[n]one of the prior art of record teaches or suggests either an ascorbic composition consisting essentially of the specific components, ascorbic acid, a food acid and a phosphate in a specific amount or that such ascorbic acid composition would be effective as a slow-acting oxidizing agent so that it would effectively replace a slow-acting oxidizing agent such as potassium brómate.” J.A. at 2827. U.S. Patent No. 5,510,129 for a “potassium brómate replacer composition” issued to Kim on April 23,1996.
Less than three weeks later, on May 14, 1996, Kim surrendered her patent and filed a “reissue application,” alleging that an error arose during the prosecution of the original patent. In applying for a reissued patent, Kim essentially sought to amend her original patent in two ways: (1) by adding claims 5-10, covering a composition comprising of ascorbic acid and food acid (but not requiring phosphate); and (2) by changing the original claims’ ascorbic acid range from 15-250 ppm to 10-300 ppm and changing the food acid range from 0.02-0.15 parts per 100 parts of flour to 0.015-0.2 parts per 100 parts of flour. In other words, Kim tried to broaden the original claims by adding new claims that did not include the phosphate limitation and by broadening all the claims’ ascorbic and food acid ranges.
The examiner initially rejected the reissue application as violating the rule against recapturing material that was surrendered or withdrawn during prosecution of the original patent. In so doing, the examiner did not state which of Kim’s changes would violate the rule against recapture. After additional amendments not relevant to this case, the examiner allowed the reissued patent on October 26, 1999, as the '355 patent.
The reissue procedure allows a patentee to broaden the scope of an existing patent to include subject matter that had been erroneously excluded from that patent. 35 U.S.C. § 251 (2000). This pro[1322]*1322cedure, however, is not without its limitations. For example, the “recapture rule prevents a patentee from regaining through reissue the subject matter that he surrendered in an effort to obtain allowance of the original claims.” Pannu v. Storz Instruments, Inc., 258 F.3d 1366, 1370-71 (Fed.Cir.2001) (internal quotation marks omitted). We have articulated a three-step process for applying the recapture rule:
The first step is to determine whether and in what aspect the reissue claims are broader than the patent claims. The second step is to determine whether the broader aspects of the reissued claim related to surrendered subject matter. Finally, the court must determine whether the reissued claims were materially narrowed in other respects to avoid the recapture rule.
Id. at 1371 (internal quotation marks omitted).
Here, the first and third steps are not at issue; that is, Kim concedes that reissued claims 5 and 10 are in fact broader than the original patented claims because they cover a non-phosphate potassium brómate replacer composition and a broader food acid range. Further, Kim concedes that neither reissued claim is narrower in any other material aspect. Thus, the only issue is whether the broader aspects of the reissued claims relate to “surrendered” subject matter. In this respect, we reject Kim’s position that she should be treated differently from other patentees because she was pro se during some parts of the prosecution, and her argument that she was not responsible for the original amendment made with her acquiescence by the examiner.
The challenger of the reissued patent, here ConAgra, must establish surrender of recaptured subject matter by clear and convincing evidence. See Superior Fireplace Co. v. Majestic Prods. Co., 270 F.3d 1358, 1367 (Fed.Cir.2001). A pat-entee can surrender subject matter either through arguments or amendments made during the prosecution of the original patent. Hester Indus., Inc. v. Stein, Inc., 142 F.3d 1472, 1480-81 (Fed.Cir.1998). Whether surrender of recaptured subject matter has occurred is a question of law, which we review de novo. See N. American Container, Inc. v. Plastipak Packaging, Inc., 415 F.3d 1335, 1349 (Fed.Cir.2005).
The district court here suggested that the patentee’s subjective intent should be evaluated in determining whether the patentee surrendered subject matter. Some of our recapture decisions explain that “[e]rror under the reissue statute does not include a deliberate decision to surrender specific subject matter in order to overcome prior art,” Mentor Corp. v. Coloplast, Inc., 998 F.2d 992, 996 (Fed.Cir.1993) (emphasis added), and that the prerequisite error for a reissue can exist if “there is no evidence that the [applicant] intentionally omitted or abandoned the claimed subject matter.” Ball Corp., 729 F.2d at 1435-36 (emphasis added). But these cases do not suggest that the paten-tee’s subjective intent is pertinent to the question of surrender. These decisions simply distinguish between a patentee’s inadvertent “error” (for which the reissue statute provides a remedy), and a paten-tee’s “surrender” (for which the recapture rule prevents a reissue).10
[1323]*1323It is clear that in determining whether “surrender” of subject matter has occurred, the proper inquiry is whether an objective observer viewing the prosecution history would conclude that the purpose of the patentee’s amendment or argument was to overcome prior art and secure the patent. This is because the recapture rule is aimed at ensuring that the public can rely on a patentee’s admission during prosecution of an original patent. “It is precisely because the patentee amended his claims to overcome prior art that a member of the public is entitled to occupy the space abandoned by the patent applicant. ... [T]he reissue statute cannot be construed in such a way that competitors, properly relying on prosecution history, become patent infringers when they do so.” Mentor Corp., 998 F.2d at 996; see also Vectra Fitness, Inc. v. TNWK Corp., 162 F.3d 1379, 1384 (Fed.Cir.1998) (“[T]he ‘recapture rule’ prevents a patentee from regaining through reissue subject matter surrendered during prosecution, thus ensuring the ability of the public to rely on a patent’s public record,.”) (emphasis added).11 Thus, if the objective public observer can discern a surrender of subject matter during the prosecution of an original patent in order to overcome prior art and obtain the patent, then the recapture rule should prevent the reissuing of that patent to claim the surrendered subject matter.
With this in mind, we turn to ConAgra’s allegations of surrender. ConAgra contends that during the prosecution of the original patent, Kim surrendered (1) a non-phosphate potassium brómate replacer composition, and (2) a potassium brómate replacer composition .with a food acid range broader than 0.02-0.15 parts per 100 parts flour.
First, with respect to the non-phosphate potassium brómate replacer composition, ConAgra contends that Kim added phosphate to all of the claims in her continuation-in-part application in order to overcome the initial rejection of her original application as obvious over Tanaka and other prior art references. ConAgra argues that the addition of phosphate was a surrender of non-phosphate potassium brómate replacer claims, which Kim later recaptured in the reissued patent. To support its view that the addition of phosphate constitutes a “surrender,” ConAgra points to the examiner’s “Reasons for Allowance” of Kim’s continuation-in-part application, which stated that the prior art does not “teach[ ] or suggest[ ] ... an ascorbic composition consisting essentially of the specific components, ascorbic acid, a food acid and a phosphate in a specific amount.” J.A. at 2827. Like the district court, we are not persuaded by ConAgra’s arguments. Kim overcame the obviousness rejection by changing the transition phrase from “comprising” to “consisting essentially of’ and by changing her method claims to composition claims. While the phosphate limitation was added at the same time, the prosecution history does not indicate that Kim added that limitation in particular in order to overcome the obviousness rejection. Significantly, the examiner had previously rejected claims of the original application that included phosphate and noted that the phosphate salt limitation there was not “patentably significant.” J.A. at 2735. Thus, the prosecu[1324]*1324tion history refutes the argument that phosphate was added by Kim to overcome a rejection.
Second, with respect to the food acid range, ConAgra argues that Kim surrendered a lower limit for her food acid range when she changed the range from 0.03-0.2 parts by weight of flour in the dough in her original application to 0.02-0.15 parts per 100 parts of flour in her continuation-in-part application. ConAgra contends that Kim later recaptured the surrendered lower limit when she broadened the food acid range to 0.015-0.2 parts per 100 parts of flour in her reissued patent. ConAgra suggests that Kim narrowed her food acid range in order to distinguish her claim from the Tanaka reference. However, this assertion is belied by the prosecution history. As the district court explained, “the range for the food acids used in the pertinent prior art (Tana-ka) had been [0].0005 to [0].006. Plaintiffs lower end choice of [0J.015 [in the reissue application] or 0.02 [in the original application] are both a significant difference from [0].006. It can not be inferred that plaintiffs choice of [0].020 instead of [0].015 was because plaintiff was surrendering the difference between the two out of fear [0].015 would be found to be obvious while [0].020 would not.” J.A. at 5196. Further, “[t]he Patent Examiner did not indicate that [the original application’s] range [of 0.03-0.2] was obvious in light of the prior art. Instead, the Patent Examiner indicated that the use of food acid and ascorbic acid in general was disclosed by the prior art and that the particular range ... was indefinite in that it was unclear if it was measured solely in ratio to flour.” J.A. at 5194-95. We agree with the district court. We therefore affirm the district court’s denial of ConAgra’s motion for JMOL of invalidity based on the recapture rule.
B Anticipation and Obviousness
The next question is whether the district court correctly determined that the jury verdict of no invalidity was supported by substantial evidence. In this connection, the burden was on ConAgra to establish invalidity by clear and convincing evidence. Honeywell Int’l v. Hamilton Sundstrand Corp., 370 F.3d 1131, 1145 (Fed.Cir.2004).
The same claim construction governs for validity determinations as for infringement determinations. See Door-Master Corp. v. Yorktowne, Inc., 256 F.3d 1308, 1312 (Fed.Cir.2001). Having affirmed the district court’s claim construction, which requires Kim’s potassium bró-mate replacer to have essentially the same functions as potassium brómate, any anticipatory prior art reference must necessarily exhibit those same functions. ConAgra makes virtually no effort to show that the asserted prior art references disclose such functions. However, even if we assumed that these prior art references disclosed compositions with the claimed functionality, there was substantial evidence that the references did not contain the claimed proportions of ascorbic and food acids.
First, ConAgra argues that claim 5 was invalid as anticipated by, and obvious over, the Jorgensen patent (U.S. Patent No. 2,149,682 (issued March 7, 1939)), because Jorgensen disclosed replacing potassium brómate with lemon juice, which naturally contains both ascorbic acid and food acid (in the form of citric acid) in the ranges disclosed in claim 5.
ConAgra’s expert at trial, Dr. Hoseney, testified that concentrations of ascorbic and citric acid included in a bread mix made with Jorgensen’s formula would fall within Kim’s claimed ascorbic and food acid ranges. On cross-examination, Hose-ney was questioned about how he determined the ascorbic and citric acid concern [1325]*1325trations in lemon juice, and he explained that he used averages from a food chemistry book. He also acknowledged that the acid level in individual lemons vary and that he did not himself “press any lemons in the manner mentioned in the Jorgensen patent” or “do any tests on lemon juice” in order to come to his conclusion. J.A. at 767, 775.
“What a prior art reference discloses in an anticipation analysis is a factual determination.” Novo Nordisk Pharm., Inc. v. Bio-Tech. Gen. Corp., 424 F.3d 1347, 1355 (Fed.Cir.2005) (internal citations omitted). Here, the jury was free to disregard Hoseney’s testimony because Hoseney did not conduct any tests to determine the acid concentrations in the product produced by the Jorgensen formula. See, e.g., Liquid Dynamics Corp. v. Vaughan Corp., 449 F.3d 1209, 1218 (Fed. Cir.2006) (“It is not our duty ... to reevaluate the weight or credibility of the evidence.”). Having found that claim 5 is not shown obvious by the Jorgensen reference, the jury likewise could have found that claim 10, which adds the additional limitation of yeast, was not obvious over Jorgen-sen.
ConAgra further argued that claims 5 and 10 are obvious over the De-Stefanis patent application (U.KApp. No. 2,264,429), because that reference includes ascorbic and food acids within the ranges of those claimed by Kim.12
DeStefanis disclosed three formulations of bread improver compositions including varying amounts of ascorbic acid, food acid and several other ingredients. Kim concedes that DeStefanis disclosed ascorbic acid ranges within her claimed ascorbic acid ranges. However, ConAgra and Kim dispute whether DeStefanis disclosed food acid ranges within Kim’s claimed ranges. While the DeStefanis reference contains numeric values assigned to food acid, it is not entirely clear what scale of measurement DeStefanis assigned to these numeric values. On the one hand, the ascorbic acid and food acid values are listed in columns under the heading “Formulation (ppm),” suggesting that the food acid values are being given in ppm. On the other hand, the reference also includes another list of ascorbic acid in ppm which does not correspond to the first set of ascorbic acid values, suggesting that the food acid values listed under the “ppm” column might actually be percentages. ConAgra adopts [1326]*1326this latter view, suggesting that the “ppm” header in the DeStefanis patent is a typographical error and that when the food acid values are read as percentages, they are within Kim’s claimed ranges. During trial, Kim’s testified about the DeStefanis reference and suggested that it was improper to read the reference as ConAgra does. The determination of what a prior art reference discloses is a question of fact. The jury was entitled to believe Kim and find that this reference does not disclose food acid ranges within Kim’s ranges. See Novo Nordisk Pharm., Inc., 424 F.3d at 1355.
We thus conclude that the jury verdict that the claims were not invalid was supported by substantial evidence.
CONCLUSION
For the foregoing reasons, the decision below is affirmed.
COSTS
No costs.
AFFIRMED.